Search

SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) on-board the ESA Envisat satellite platform provided daily solar spectra in the wavelength region from 0.24 μm to 2.4 μm. The instrument was operating for nearly a decade from August 2002 to April 2012. This document reports on the validation of the SCIAMACHY solar spectral irradiances (SSI) in its data version 8. Like other UV satellite sounders, the SCIAMACHY spectrometer suffers from optical degradation due to polymerisation of optical surfaces from the harsh UV radiation in space (e.g. Bramstedt et al., 2009; DeLand et al., 2012; Krijger et al., 2014). In data version 8 of SCIAMACHY a physical model of the scanner unit was implemented to provide a degradation correction (Bramstedt et al., 2009; Krijger et al., 2014). Comparisons with several other established solar reference spectra show agreement to within 4 % in most parts of the visible and near infrared from 350 to 1400 nm.

Aus spektral hoch aufgelösten Messungen im ultravioletten (UV) und infraroten (IR) Spektralbereich können mittels einer Tikhonov Regularisierung vertikale Ozonprofile in der Stratosphäre und Troposphäre invertiert werden. Der neu geschaffene Retrieval-Algorithmus TOPAS (Tikhonov regularized Ozone Profile retrievAl with SCIATRAN) ermöglicht die kombinierte Auswertung beider Spektralbereiche und enthält einen neuen und verbesserten Ansatz der Re-Kalibrierung der UV Messungen. In der Stratosphäre liefern die UV Messungen des Instruments TROPOMI auf dem Satelliten S5P sehr genaue Ozonwerte, aber in der Troposphäre ist ihr Informationsgehalt begrenzt. Daher wurden zusätzliche IR Messungen von CrIS auf Suomi-NPP verwendet. Die Kombination beider Spektralbereiche erhöht den Informationsgehalt des Ozonprofilretrievals in der oberen Troposphäre und in der unteren Stratosphäre. In diese Arbeit werden die Ozonprofile in der Stratosphäre und in der Troposphäre mit anderen satellitengestützten Ozonprofilen, Ozonsonden und troposphärischen und stratopshärischen Lidarsystemen validiert und die Ergebnisse präsentiert.

Hydroperoxyl (HO2) and organic peroxy (RO2, where R stands for any organic group) radicals are highly reactive molecules produced in the oxidation of many compounds in the troposphere. They participate in the catalytic cycle producing or destroying ozone (O3) in the troposphere. Thus, HO2 and RO2 measurements provide unique information about the chemical processing of an air mass. Over the last decades, the understanding of the role of HO2 and RO2 in the chemical processes in the planetary boundary layer (PBL) has improved through ground-based in-situ measurements. However, the number of unequivocal measurements of peroxy radicals in the free troposphere is still quite limited. Measurements from airborne platforms offer a unique opportunity to measure HO2 and RO2 together with other relevant trace gases to test and improve the understanding of their chemistry in the free troposphere. During this doctoral study, an extensive set of airborne RO2* (RO2* = HO2 + ∑RO2, where RO2 represents the organic peroxy radicals reacting with NO to produce NO2) measurements in the PBL and free troposphere was acquired, analysed and interpreted. The RO2* measurements were made using the Peroxy Radical Chemical Enhancement and Absorption Spectrometer (PeRCEAS) developed at the Institut für Umweltphysik (IUP) of the University of Bremen. PeRCEAS has successfully deployed onboard the High Altitude LOng range research aircraft (HALO) in three research campaigns: the Oxidation Mechanism Observations (OMO) Asia and the Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales (EMeRGe) field missions in Europe and Asia. The PeRCEAS instrument was characterised and calibrated under atmospherically representative conditions in the laboratory to assure data quality, reproducibility, accuracy and to define optimal operating conditions for the airborne measurements. PeRCEAS successfully measured RO2* in 33 HALO flights. RO2* mixing ratios of up to 120 pmole mole-1 were measured in air masses having different origins, chemical compositions and physical conditions in Europe and Asia. The RO2* measurements, the simultaneous measurements of other relevant trace gases, aerosol concentration, photolysis frequencies and other meteorological parameters were synergistically analysed to identify the chemical processes controlling the amount of RO2*. From the analysis, it was found that RO2* is primarily produced following the photolysis of ozone (O3), formaldehyde (HCHO), glyoxal (CHOCHO), and nitrous acid (HONO) in the air masses investigated. The estimate for the contribution of O3 photolysis to RO2* production rate is > 40 % in the PBL and < 40% in the free troposphere. This reduction is explained by the decrease in the water vapour concentration ([H2O]) as a function of altitude. Subsequently, the RO2* mixing ratios in the air masses measured during the EMeRGe in Asia and Europe campaigns were calculated assuming a photostationary steady-state (PSS) for RO2*. The RO2* production from precursor photolysis, the loss through HO2 – HO2, RO2 – RO2 and HO2 – RO2 reactions, the hydroxyl radical (OH) and organic oxy-radicals (RO) loss during the radical interconversion, and HO2 uptake on aerosol were considered for the calculation of RO2*. The calculations were constrained by the simultaneous measurements of photolysis frequencies, trace gas concentrations and aerosol particle number concentrations onboard HALO. Case studies confirmed the validity of the PSS assumption for air masses having different chemical compositions under different physical conditions. The RO2* calculated are generally in excellent agreement with the RO2* measurements. An experimental budget analysis was performed to estimate the main loss processes of RO2* by introducing the RO2* measurements in the PSS equation. Except for the measurements inside pollution plumes with NO > 800 pmole mole-1 or aerosol particle number concentration > 800 particles cm-3, the HO2 – RO2 and HO2 – HO2 were the dominant RO2* loss process during both EMeRGe Asia and Europe. The RO2* losses through HO2 uptake on aerosol were higher in the pollution outflows measured in Asia than in Europe. This is attributed to the higher aerosol concentrations observed in the air masses probed during EMeRGe in Asia. The contribution from the HO2 uptake on aerosol increases up to 60 % for an assumed aerosol uptake coefficient of 0.24 inside pollution plumes in Asia, where the aerosol particle number concentration is > 1000 particles cm-3. In Europe, the OH – NOx reactions were the dominant RO2* loss process in the pollution outflow. This finding is explained by the EMeRGe in Europe measurements being typically closer to anthropogenic emissions sources than in Asia, except for the case study of Taipei and Manila.

Bromine plays a crucial role in polar atmospheric composition. During springtime, photochemistry converts bromine compounds originating from ice and snow into gaseous reactive bromine radicals (Br), which deplete ozone in the boundary layer, forming bromine oxides (BrO). Due to the autocatalytic nature of the reaction mechanism, it has been called bromine explosion. The strong relationship of bromine photochemistry and release from its sources to ozone depletion events (ODEs) was discovered in the late 1980s. Since then, and because of the importance of tropospheric ozone (the primary source of hydroxyl radical (OH), the major oxidizing agent of the atmosphere), many studies focused on the mechanisms which release bromine into the troposphere and the driving parameters which enhance BrO production and therefore ozone depletion. Arctic Amplification (AA) is the phenomenon that surface temperature in high latitudes increases more rapidly than at lower latitudes. One of the most profound consequences of AA is the significant changes in sea ice conditions. Sea ice extent, age and thickness are drastically changing. Inevitably, all aspects of the Arctic ecosystem are expected to be affected by Arctic Amplification. Remote sensing from satellites can be extremely useful for studying the Arctic region. By the end of the 1970s, sea ice concentration was successfully monitored by satellite sensors. Since 1995, we also have the ability to study atmospheric composition worldwide with data retrieved from nadir radiance spectra from a series of European satellite sensors: GOME on ERS-2 (1995 - 2003), SCIAMACHY on ENVISAT (2002 - 2012), GOME-2A on MetOpA (2007 - today) and GOME-2B on MetOpB (2012 - today). The focus of this thesis is twofold: firstly, to create the first consolidated and consistent long-term (1996 to 2017) tropospheric BrO dataset for the Arctic region and the Hudson Bay (a well-known hotspot for bromine explosion events), retrieved from the four ultraviolet-visible (UV-VIS) sensors mentioned above, in order to assess the changes and the impact that AA has on tropospheric BrO. Since the different satellite instruments have different instrumental attributes and the fact that BrO is a weak absorber in the UV spectral region, many sensitivity retrieval tests have been performed in order to identify the proper fitting settings for each instrument and to derive a high-quality BrO dataset with high consistency between the instruments. Vertical column densities (VCD) of tropospheric BrO are extracted from total (geometric) VCDs, using a climatology of stratospheric BrO VCDs from a chemical transport model. The BrO time-series (geometric and tropospheric VCDs) show remarkable agreement during the overlapping periods between the sensors (the best agreement being between SCIAMACHY and GOME-2A with a correlation coefficient squared of 0.97). Additionally, the agreement is verified by studying daily and monthly maps of geometric and tropospheric BrO VCD. This agreement allows us to create a merged tropospheric BrO VCD dataset, the basis for deriving geophysical conclusions on the impact of AA on the Arctic BrO atmospheric composition. By studying the trends of tropospheric BrO VCDs, we infer an increase of around 1% per year. The increase is significant during polar spring, reaching 1.5% per year. A similar increase can be observed for the Hudson Bay, where tropospheric BrO VCD have increased around 0.9% per year for the spring period and 2.3% per year for the winter period. However, the increasing trend is not monotonic, and variability on the tropospheric BrO VCD appear (e.g. 2016 and 2017 are lower than 2015 for the Arctic region), as many parameters influence bromine release and subsequent BrO formation. Secondly, the link of observed tropospheric BrO VCDs to possible bromine sources and favoring weather conditions was investigated. The primary source of inorganic bromine release in the Arctic atmosphere is sea ice, especially first year ice, which is rich in sea salts. Therefore, a long-term sea ice age dataset from NSIDC was compared to the tropospheric BrO VCD dataset. The increase of first year ice extent due to the changes in the Arctic climate is in general agreement with the observed increase in tropospheric BrO, with a moderate daily correlation coefficient of +0.32, but a strong yearly one of +0.62. Also, the increase of the occurrences of first year ice over some regions in the Arctic (i.e. northeast of Greenland) is correlated with the increase of tropospheric BrO VCD in these regions. Apart from the bromine sources, driving mechanisms, like air temperature, wind speed, boundary layer height, and cyclone activity, can contribute to the Amplification, transport, vertical uplifting and recycling of tropospheric BrO plumes. Consequently, similar comparisons have been performed between tropospheric BrO and meteorological data. We infer that the parameter with the most substantial influence on the formation of bromine explosion events is air temperature, with a correlation coefficient of -0.54 (anti-correlation) for the Arctic during spring and -0.78 for Hudson Bay spring. Furthermore, the spatial agreement and correlation between trend maps of tropospheric BrO VCD and air temperature verify the anti-correlation between the two quantities. However, the bromine release and the formation, transport, and re-cycling of BrO plumes are complex and dynamic phenomena. They depend on many geophysical parameters, and there are also complex relationships between these parameters. Therefore, single individual linear comparisons between tropospheric BrO VCDs and key parameters of BrO formation cannot fully represent the actual relationship between them. This leads us to the effort of employing, for the first time, an artificial intelligence neural network in order to model and predict Arctic tropospheric BrO VCDs using the parameters contributing to tropospheric BrO formation. By training the neural network only with one year of data, it can reproduce accurately (both spatially and in magnitude) many BrO plumes which occurred in other years. This ability of the neural network to efficiently model some bromine explosion events allows us to distinguish them between those occurring at the surface and those at higher altitudes. From studying the effect of each of the individual key parameters on the magnitude of modeled tropospheric BrO VCD, we conclude that air temperature and mean sea level pressure (which can describe the boundary conditions under which bromine is released) have the highest impact.

Global warming is already impacting the modern ocean. To recognize changes and predict the future ocean, ocean color (OC) remote sensing aims at quantifying and monitoring optically active oceanic constituents such as phytoplankton, as well as the underwater light field, on synoptic scales. The underwater light field is typically characterized by the diffuse attenuation coefficient (Kd), which describes how fast the downwelling light diminishes with depth. Phytoplankton diversity is typically assessed by grouping phytoplankton with respect to their function in biogeochemical cycles, which are described as phytoplankton functional types (PFT). Typically, OC sensors record radiometric measurements at several bands, 10-20 nm wide, in the visible and near-infrared. However, direct information of OC variables in the ultraviolet (UV) spectral range is still widely lacking. Also, the coarse spectral resolution of traditional OC sensors hampers the retrieval of information on biodiversity, e.g., represented through PFT, and ecosystems. While OC sensors have weaknesses in spectral resolution, a suite of atmospheric satellite sensors measures radiation at high spectral resolution (about 0.5 nm) and in spectral ranges (UV) not provided by typical OC sensors. These sensors are designed for the retrieval of atmospheric trace gases using Differential Optical Absorption Spectroscopy (DOAS) and have been utilized for OC retrievals by an adaptation of this method to the ocean domain. PFT, light attenuation and availability, and chlorophyll-a fluorescence have been successfully derived from radiances recorded by the atmospheric sensor SCIAMACHY between 2002 and 2012. So far, only little experience has been gathered with other SCIAMACHY-like sensors, limited to fluorescence retrievals at red wavelengths. This thesis focuses on retrievals of OC variables in the UV to green spectral range from multiple atmospheric sensors, namely SCIAMACHY, GOME-2, OMI, and TROPOMI. By comparison of OC retrievals from multiple sensors, insight can be gained on retrieval robustness and sources of uncertainty. Merging of data sets from multiple sensors is desirable for creating long time series necessary for observing climate change impacts. Three hypotheses are investigated: (1) OC variables in the blue-green spectral range, such as PFT and the diffuse attenuation coefficient, can be successfully retrieved from multiple SCIAMACHY-like sensors; (2) OC variables from multiple SCIAMACHY-like sensors can be merged to create long time series; and (3) UV-visible bands of SCIAMACHY-like sensors can be exploited for the retrieval of novel OC products in the UV. The thesis comprises three studies. Two studies concentrate on the diffuse attenuation coefficient with the second study focusing on novel Kd products in the UV. The third study utilizes knowledge from the first two studies to retrieve two key PFT, diatoms and coccolithophores, in the Southern Ocean. Based on experience gathered with the SCIAMACHY sensor, the retrieval of OC variables was adapted to the other atmospheric sensors and further improved to provide complementary and novel OC information. The mean Kd in the blue spectral range, 390 to around 425 nm, was successfully derived from measurements taken by GOME-2, OMI, TROPOMI (as well as SCIAMACHY). Coccolithophores were successfully retrieved from GOME-2 data in the Southern Ocean, however, diatom retrievals were found to be more challenging and resulting data quality was deemed insufficient. Intersensor biases were found between the derived Kd data sets as well as for the derived PFT data in comparison to the established SCIAMACHY PFT time series prior to this work. Complex instrument-specific corrections would be necessary to remove these biases. Biases were successfully reduced, but unfortunately merging of the multiple data sets is still not possible at this stage. The UV-blue spectral range was exploited for deriving two novel Kd products in the UV, 312.5 to 338.5 nm and 356.5 to 390 nm. Comparison with field measurements and sensitivity analysis of the retrievals showed promising results. Findings from the third study on Southern Ocean PFT support the Great Calcite Belt hypothesis, which suggests that coccolithophores cause a wide band of enhanced water reflectivity around Antarctica, and indicate that total chlorophyll-a concentration is not an adequate variable for predicting coccolithophore abundance. Spectral-based PFT retrievals, as used in this thesis, are found to be more suitable. Future applications of the data sets derived and characterized in this thesis include: the estimation of the oceanic heat budget and the UV dose rate on marine organisms, the investigation of the sources of colored dissolved organic matter and of phytoplankton photoprotective pigments, as well as residence times of particulate inorganic carbon in the upper ocean.

This thesis presents MAX-DOAS measurements of the air pollutants NO2 and SO2 in the marine environment of the North and Baltic Sea and the surrounding coastal areas. As the first part, the results from more than three years of MAX-DOAS measurements on the island Neuwerk in the German Bight are presented. As the second part, a novel application of an "onion peeling" like approach to MAX-DOAS measurements of shipping emissions on Neuwerk was developed, aiming at investigating the strong horizontal inhomogeneities in NO2 over a shipping lane. In the third part, expanding the research area from the German North Sea coast to the entire greater North Sea area and the German part of the Baltic Sea, shipborne MAX-DOAS measurements for air quality assessment have been performed for the first time on a regular basis in this area on routinely conducted survey cruises in cooperation with the German Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie, BSH).

Bromine compounds have received growing attention due to their impact on the atmospheric chemistry in particular ozone chemistry and the resulting oxidation capacity. Reactive bromine is involved in chain reactions that deplete ozone in the stratosphere as well as catalytically destroy ozone in the troposphere leading to nearly complete removal near the surface called as an ozone depletion event (ODE). Bromine monoxide (BrO) is the most commonly observed bromine species and large amounts of BrO are observed in the polar regions during spring time through bromine explosion events. Over the last decades, BrO vertical column density has been retrieved with satellite-based UV–visible instruments such as GOME, SCIANACHY, OMI and GOME-2 for the monitoring of bromine amounts in various source regions. In particular, TROPOMI which was launched in October 2017 provides daily global coverage as the predecessor instruments, but with its unprecedented high spatial resolution (3.5x5.5 km2), this instrument enables to detect spatial variations and small-scale emission sources in more detail. The aim of my doctoral project is to develop an advanced algorithm to derive accurate total and tropospheric BrO columns by using the improved spatial resolution of TROPOMI data. In the first part of this thesis, a description of total/tropospheric BrO retrieval algorithm is presented. Optimized DOAS settings for the BrO retrieval are determined based on sensitivity tests under various measurement conditions. Approaches for the stratospheric correction to separate the tropospheric partial columns from total BrO columns are tested using several different methods. Also, air mass factor calculations for TROPOMI are performed by considering various observation conditions. As a consistency test, TROPOMI BrO columns are compared with OMI and GOME-2 retrieval results on both global and regional scales. Satellite BrO retrievals for a large spatial coverage over a long-term period can be used to explain the causes of BrO enhancements in the polar regions during spring and the role and characteristics of meteorological factors contributing to them. The relationship between satellite total BrO vertical columns and meteorological fields including sea level pressure, surface level wind speed and direction, surface air temperature, and tropopause height are investigated in this study. Statistical analysis using decadal GOME-2A/B observations reveals spatial and temporal behaviors of total BrO column enhancements in the Arctic and Antarctic. Also, differences in meteorological conditions and their regional characteristics between enhanced BrO situations and the mean field are identified, which shows effects of meteorological parameters on BrO enhancement processes. Finally, the satellite BrO retrieval algorithm developed in this thesis is verified by comparing satellite BrO columns with ground-based MAX-DOAS BrO measurements in Ny-Ålesund, Svalbard, operated by IUP-Bremen DOAS group. The possibilities and needs for improving the BrO retrieval algorithm are discussed based on the satellite retrieval algorithm validation results. Also, using both satellite and ground-based MAX-DOAS tropospheric BrO retrievals, bromine explosion event cases in Ny-Ålesund are investigated in detail, and moreover, capabilities of TROPOMI to investigate small-scale halogen chemistry are discussed.

Shipping is a major contributor to pollution in coastal areas and harbour towns. It is a growing industry and only few international regulations control its emissions. This thesis describes the set-up and analysis of in-situ measurements at different locations near the German coast, which are influenced by shipping emissions. It focusses on the analysis of a unique and extensive set of plumes measurements, which have been allocated with individual ships. A total of nearly 5 000 plumes could be analysed, especially with respect to their fuel sulphur content (FSC), based on SO2 measurements, and their NOx emission factors. The studies described in this thesis, which are the first of their kind in Germany in this extent, have laid the foundations for the future operational systems determining the pollution emissions from shipping and assessing their compliance with legislation.

Air pollution affects human health, ecosystems, and the climate. For a better understanding of air pollution, continuous monitoring, measurement validation, and measurement improvement is needed. Therefore, ground-based and satellite-based measurements as well as model data are analysed in this thesis with the main goal to improve the knowledge about the trace gas vertical distribution. The data are compared for three different environments: rural, biomass burning, and industrialised areas. Two different nitrogen dioxide (NO2) vertical column density retrievals for satellite measurements are compared with ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) data above Xianghe, China. The influence of satellite retrievals' a priori assumption is investigated on their agreement with MAX-DOAS data. The a priori profiles are an important difference between the retrievals' input parameters. For this purpose, the MACC2 interim reanalysis data and the MOZART-2 model are used. Generally, the retrieval version with MACC2 interim reanalysis a priori profiles agrees better with the ground-based MAX-DOAS measurements. Furthermore, the NO2 columns are often higher for cloudy scenes than for cloud-free scenes in this area in winter, which might be related to aerosols. Thus, the influence of the cloud fraction and the aerosol content of the atmosphere on the differences between the two retrievals are discussed which provides also the opportunity to understand and reduce the differences between measurements from satellite and ground-based platforms. Not only above industrialised areas but also above rural areas validation measurements are needed. Due to the low pollutant content in these areas, the relative uncertainties of satellite measurements are high. There, satellite data regularly show enhanced levels of short-lived pollutants, which are unexpected to be present in the atmosphere at high levels so far away from any sources. Therefore, MAX-DOAS measurements were taken in the remote Atlantic Ocean to validate satellite measurements. For formaldehyde (HCHO) and glyoxal (CHOCHO), the latitudinal dependency of the MAX-DOAS measurements is similar to satellite observations and model simulations. The trace gas origin could be the African continent. Because of long transports of up to four days, the enhanced values might be related to the export of precursors from the continent which are transformed to HCHO and CHOCHO. Furthermore, the detected outflow is in elevated layers which is in agreement with FLEXPART backward simulations leading to an altitude between 1000m to 5000m. Thus, these results improve the confident in satellite measurements above remote ocean areas. The knowledge of the trace gas vertical distribution on a global scale is generally limited due to the low vertical information content of spectroscopic measurements for the absorbers. However, retrievals in different spectral ranges from satellite measurements can globally provide insight into the vertical distribution of NO2. Therefore, a new NO2 retrieval in the ultra violet spectral range was developed and compared with the standard retrieval in the blue spectral range. Due to the differences in sensitivity to the lower atmosphere, a rough estimation of the NO2 vertical distribution is possible from these two satellite retrievals. In anthropogenically polluted areas, the differences are large between the two slant column densities (approximately 60%), which indicates that the air pollution is located close to the ground. In contrast, the NO2 is uplifted into elevated layers in biomass burning areas which is reflected by reduced differences of approximately 36% between the two spectral ranges. Additionally, models can be validated by converting slant column densities into vertical column densities for both spectral ranges. In theory, if the a priori profiles are correct, the vertical column densities should be similar. Two models, TM5-MP and the MACC2 interim reanalysis data, are used for the conversion into vertical column densities. In total the TM5-MP leads to a better agreement between the ultra violet and blue spectral range. However, in this model the NO2 seems to be located too high in the atmosphere.

In this thesis, the methods to retrieve aerosol extinction coefficient (Ext) and particle size distribution (PSD) parameters from the remote sensing instruments measuring in the limb-viewing geometry are presented. The Ext retrieval algorithm is applied for SCIAMACHY instrument as well as for OMPS measurements. These products compose global stratospheric aerosol databases, which are covering over 16 years. Additionally, the aerosol PSD parameters are retrieved in the tropical region (20AAdegreeN-20AAdegreeS) from SCIAMACHY limb measurements, creating a unique product. Both, Ext and PSD products were validated through comparison with other space-borne and in situ measurements, showing good and consistent results. In the thesis, the case studies analyzing changes in Ext and PSD parameters after volcanic eruptions of Manam and Tavurvur are presented. Additionally, the evolution of Ext after eruptions of Sarychev Peak and Kelut as well as after Canadian Wildfires of 2017 is analyzed.

In this thesis, spatial and temporal tropospheric inhomogeneities in the distribution of nitrogen dioxide (NO2), formaldehyde (HCHO) and aerosols are investigated. The analysis was done on a three years dataset (2015 - 2017) of ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements in Bremen. MAX-DOAS measurements were investigated in three different azimuthal viewing directions in order to analyse lateral changes in the distribution of NO2 and HCHO in Bremen. A clear seasonality was found and explained by anthropogenic and biogenic emissions for NO2 and HCHO, respectively. While no significant azimuthal variability for HCHO was found, NO2 differs strongly for the westerly and southerly directions due to lateral inhomogeneities and a more frequent pointing towards the sun which has a strong impact on the results. In order to localize possible dominant emission sources of NO2 within the area of Bremen, the onion peeling approach was successfully applied by usage of the three fitting windows in the ultra-violet (UV) and visible (vis) spectral range. Strong emitters could be identified having a large impact on average NO2 results. A major challenge for the analysis of trace gases in the troposphere is the usually insufficient knowledge of aerosols, which might have a large impact on spectroscopic measurements. The novel MAX-DOAS profiling algorithm BOREAS was developed and its accuracy is validated with the help of synthetic data as well as ancillary measurements of the CINDI-2 field campaign (Cabauw, the Netherlands, 2016). In contrast to other algorithms, BOREASa aerosol information are retrieved by minimizing the difference of O4 optical depths of measurements and forward modelling calculations. The resulting aerosol extinction coefficient profiles were used for the retrieval of vertical trace gas concentration profiles. In this thesis, several retrieval modes and various ways of improving the regularization between measurement and a priori constraints as well as the selection of proper a priori profiles by use of a priori pre-scaling were investigated. The BOREAS algorithm was finally applied to the full MAX-DOAS dataset, and three years of aerosol and trace gas vertical profiles from the measurement location Bremen are presented and discussed with the help of in-situ as well as AERONET measurements. Seasonal, weekday and diurnal cycles for aerosols and NO2 were found which could be attributed to near surface emissions mainly from traffic and power plants. The seasonal cycle of HCHO is found to be dominated by biogenic emissions in summer, in addition to a smaller fraction of anthropogenic emissions in winter. While NO2 and aerosols are mainly focussed in layers close to the surface, larger HCHO concentrations could also be observed in the complete planetary boundary layer showing the need for the analysis of vertical concentration profiles of trace gases in the troposphere.

Methane (CH4) is the second most important anthropogenic greenhouse gas. Its atmospheric concentration is significantly influenced by human activities and has increased over the past years. The adverse effects of such a greenhouse gas on the climate system has identified need to control its emissions. However, an accurate assessment of the different emission sources by existing observations remains challenging. Consequently, the methane budget still has significant uncertainties, especially for local sources. In this study, an attempt was made to quantify emissions for areal sources and complex source regions (about 1 to 90 km2 in area) using passive remote sensing data and in-situ data. The data set was collected during the COMEX (CO2 and MEthane eXperiment) research campaign in California in 2014. It comprised observations of CH4 by airborne remote sensing non-imaging (Methane Airborne MAPper, MAMAP) and imaging (Airborne Visible / Infrared Imaging Spectrometer - Next Generation, AVIRIS-NG) instruments as well as aircraft in-situ observations of CH4 and carbon dioxide (CO2) with a Picarro greenhouse gas in-situ analyser. The main objective was the quantitative analysis of emissions from prominent CH4 sources such as landfills and oil fields and, if present, also accompanying CO2 emissions. In particular, the unique spectroscopic measurements in the short wave infrared region from the MAMAP remote sensing instrument have successfully been used for this purpose. This was also the first time that CH4 emissions from an entire landfill and an oil field complex were quantitatively estimated from airborne remote sensing data. Elevated CH4 concentrations (or 'CH4 plumes') were detected downwind from landfills and across oil fields by remote sensing aircraft surveys using the MAMAP instrument. Following each remote sensing survey, the detected plumes were sampled within the atmospheric boundary layer by in-situ instruments on the same aircraft for atmospheric parameters such as wind information and dry gas mole fractions of CH4 and CO2. These measurements facilitated an independent assessment and verification of the surface fluxes. During the COMEX campaign, four landfills in the Los Angeles Basin were surveyed, where one landfill repeatedly showed a clear emission plume on four flight days. Additionally, an oil field complex in the San Joaquin Valley was investigated on seven days. Emission rates estimated from the MAMAP remote sensing and Picarro in-situ observations via mass balance approaches vary between 11.6 and 17.8 ktCH4/yr for the landfill, and between 31.0 and 47.1 ktCH4/yr for the oil field complex for several overpasses. Case-dependent relative uncertainties are between 17% to 45%. Furthermore, the in-situ and remote sensing based emission rates agree well within the error bars. The reported inventory value of the landfill of 11.5 ktCH4/yr for 2014 by the US Environmental Protection Agency (EPA) is on average 2.8 ktCH4/yr lower than the top-down estimate from this study. The top-down estimates of the oil field complex are consistent with the latest inventory estimate but can differ significantly if basic assumptions of production rates and emission factors are used yielding only around 6 ktCH4/yr. The imaging capabilities of the AVIRIS-NG instrument aboard a simultaneously flown second aircraft additionally allowed the identification of a possible leak in the landfill cover and the exact source positions of the emitters across the oil field complex.

The abundances of the atmospheric greenhouse gases carbon dioxide and methane are monitored across the globe by a network of ground-based solar absorption Fourier-transform infrared spectrometers, the Total Carbon Column Observing Network (TCCON). In this dissertation, the existing measurement time series of both gases, taken at the TCCON site in Ny-A lesund, Spitsbergen, has been augmented in two ways: extension to measurements during the polar night and the usage of middle-infrared spectra. In addition to the near-infrared TCCON measurements, spectra in the middle-infrared are routinely taken in Ny-A lesund. The newly obtained data from these spectra are compared to the standard TCCON retrieval. Additionally, in the high Arctic, measurements of solar absorption spectra are not possible in winter, because the Sun is permanently below the horizon. A new detector for measurements in the near-infrared is introduced and spectra were recorded between 2012 and 2016 to retrieve the column averaged dry-air mole fractions of CO2 and CH4. The lunar measurements were validated and compared to results from various reanalysis model simulations as well as in-situ measurements.

Studies have shown that chlorophyll fluorescence is directly linked to the photosynthetic efficiency of plants. The excess absorbed energy by leaves which has not been used in photosynthesis is re-emitted to the environment, either as heat or fluorescence. Therefore, any potential stress in plants is technically visible through monitoring fluorescence and the Solar-Induced plant Fluorescence (SIF) can thus be monitored as an indicator for vegetation growth and health status. SIF is a broad band spectral feature exhibiting two maxima at about 680 and 740 nm respectively, also known as red and far-red SIF. In the recent decades, there have been several studies addressing SIF, its importance and approaches to measure its value over vegetated regions. Among several measurement approaches, satellite-based remote sensing of SIF is particularly valuable, since the covered (spatial) area can be explicitly larger than is the case with in-situ measurements. With current space-borne instruments, even a full global coverage is attainable within a few days. In the framework of this thesis, two novel methods have been developed, tested and utilized to retrieve SIF from hyper-spectral satellite measurements. In particular, the first developed method, makes use of the Fraunhofer absorption lines in the far-red spectral region (748.5 - 753 nm), to retrieve SIF via its in-filling effect on these absorption lines. However, the satellite-based remote sensing spectrometers, used in this work, typically exhibit an additive spectral feature, which is not fluorescence. This is often accompanying the actual SIF retrieval and can significantly deteriorate the results. To account for this effect, a correction method has been developed and is combined with the retrieval algorithm. The model-based sensitivity studies confirmed the feasibility of the method to disentangle SIF from this additive feature. Additionally, the potential influences of the atmospheric and measurement conditions on the retrieval results have been assessed. Finally, the method has been applied to ten years of SCIAMACHY data and the retrieved results have been mapped on seasonal base. On a global scale, the obtained values are between 0 to 4 mW ma 2 sra 1 nma 1 . In absence of large area ground based validation data, final judgment of the results obtained in the framework of this study, is not possible. Alternatively, comparison of the achieved results with those published by the US National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) has been performed. Despite some differences, the comparison also exhibited close results, both qualitatively and quantitatively. It should be noted that comparisons among the retrievals provided by other research groups (not only GSFC) over the same spatial region is also variable depending on the instruments and methods utilized (ranging on average from a few tenths to more than 4 mW ma 2 sra 1 nma 1 ). To further assess the reliability of retrieved SIF, monthly average values have been compared to ground-based flux-tower measurements of Absorbed Photosynthetically Active Radiation by plants (APAR) and Gross Primary Production (GPP), for a time span of several years. The agreement between the seasonal trends of SIF and these parameters was significant. Although the main focus of this PhD work was on retrieving SIF in the far-red wavelength region using a spectral micro-window, there are clear scientific benefits in having an estimation over the full spectral emission range of SIF. Therefore, the second retrieval method, developed in the framework of this work, was to obtain the full spectrum of the emitted SIF by retrieving the leaf and canopy parameters, utilizing a combination of two radiative transfer models. The model-based studies showed the feasibility of the method to retrieve SIF with high accuracy. Moreover, the first results of applying this approach on GOME-2 measurements demonstrated promising outcomes. Examples of the fit quality and retrieved SIF over two different vegetation coverage types have been presented in this thesis, showing clear applicability of the method to retrieve SIF over its full spectral emission range and the potential to derive other vegetation parameters (e.g. Chlorophyll content of the leaves and the so-called leaf area index).

Volatile Organic Compounds (VOC) are key species in tropospheric chemistry, air pollution and climate. The largest fraction of VOC is emitted from natural sources, but significant contributions are also attributed to anthropogenic emissions and vegetation fires. Despite many studies estimating VOC amounts in the atmosphere and identifying their sources, the uncertainties in estimation are large. Glyoxal (CHOCHO), the smallest and most abundant of the alpha-dicarbonyls in the atmosphere, is an intermediate product in the oxidation of most VOC and an indicator of secondary aerosol formation in the atmosphere. Glyoxal in combination with other VOC (e.g. formaldehyde: HCHO) can be used for source identification of VOC. Glyoxal has been measured from space since 2003 by the SCIAMACHY and GOME-2 (MetOp-A) instruments and provides a unique global long-term dataset. The focus of this thesis is to retrieve glyoxal from measurements by the OMI instrument, to improve the SCIAMACHY and GOME-2 (MetOp-A and-B) analysis, and to investigate the resulting long-term datasets. The first part of this thesis focuses on the development of an improved retrieval for glyoxal from OMI measurements. From sensitivity tests, optimized fit parameters are determined. Two different approaches to reduce the interference of liquid water absorption over oceanic regions are evaluated, achieving a significant reduction of the number of negative columns over clear water regions. The impact of using different absorption cross-sections for water vapour is evaluated and only small differences are found. Finally, a high temperature (boundary layer ambient 294 K) absorption cross-section of nitrogen dioxide (NO2) is introduced in the DOAS retrieval to account for potential interferences with NO2 over regions with large anthropogenic emissions, leading to improved fit quality over these areas. In a sensitivity test, a spectrum of backscattered solar radiation over the Pacific Ocean is used as a reference spectrum, in order to reduce the offsets ("stripes") that sometimes are observed between viewing directions in the OMI instrument. The new retrieval has also been applied to measurements from SCIAMACHY and GOME-2 (MetOp-A and-B) instruments. Using the new CHOCHO dataset, the combination of four instruments provides more than 12 years of glyoxal measurements, which are used for the investigation of the temporal variability of VOC on a global scale. The link between vegetation, fires, anthropogenic activity, and glyoxal columns is investigated both globally and locally. This provides a general picture of where glyoxal comes from and what its temporal behaviour is depending on the region. CHOCHO and HCHO are used synergistically for the identification of VOC emission sources by computing their ratio and correlating it with indicators of biogenic emissions, fires, and anthropogenic activities, giving important information for assigning the ratios of glyoxal to formaldehyde to emission sources of VOC. In a case study, mapped averages are computed for a fire event in Russia between mid-July and mid-August 2010. Enhanced CHOCHO levels are found in close spatial and temporal proximity to elevated levels of fire radiate power, demonstrating that pyrogenic emissions can be clearly identified in the new CHOCHO data product. Also, for the first time long-range transport of glyoxal in the atmosphere has been clearly identified, where elevated levels of glyoxal follow the trajectories of simulated air masses. Finally, CHOCHO, HCHO, and NO2 columns have been retrieved from ground based measurements for two MAX-DOAS stations, which are part of the BREDOM network. Diurnal and seasonal variations have been computed for the three species and also the glyoxal to formaldehyde and formaldehyde to nitrogen dioxide ratios. The results have been compared to results from the satellite observations and with other studies.

Extraterrestrial meteoroids continuously enter the Earth's atmosphere. The bulk of the meteoric mass comes from about 220 µm sized particles coming mostly from asteroids in the asteroid belt between Mars and Jupiter. The particle size ranges from atomic scale particles to macroscopic bodies with a mass of several tons. The input rate is very uncertain, ranging from 2 to 300 tons per day. The meteoroids collide with the Earth's atmosphere at very high velocities (on the order of 10 to several 10 km per second), which leads to frictional heating of the meteoroids. This leads to full or partial ablation of the meteoroids in the upper atmosphere. Since the meteoroids consist partly of metals, this ablation leads to the formation of metal atom layers in the mesosphere and lower thermosphere (MLT). The metals are partly ionized in the MLT and metal ion layers are also formed. The MLT cannot easily be probed by in situ measurements. The pressure is too low for balloons to fly in this region, and the drag on satellites is too high there for stable satellite orbits. Therefore, only rocket-borne in situ measurements can be performed in the MLT. Because of this, remote sensing techniques are preferred to investigate the MLT. The atmospheric metal atoms and ions can be observed by re- mote sensing, because they are strong emitters of resonance fluorescence. Therefore, they are valuable tracer species for wave propagation and other transport processes in the MLT. In addition to their role as tracers, meteoric metals are also important for the chemistry in the middle atmosphere. Information on their absolute number densities is therefore of interest. The metals are involved in the formation of cluster ions and meteoric smoke particles (MSP), which are important for the heterogeneous condensation and nucleation of aerosols and clouds in the middle atmosphere. To estimate the impact of meteoric metals on the chemistry of the middle atmosphere, global observations are necessary. These need to be combined with models, which also include the yet undetectable particle species like, e.g., the metal molecules. Only in the last decades have global long-term satellite observations of the Earth's atmosphere with good local, temporal, and vertical resolution and cover- age been available. One of these data sets comes from the observations of SCIAMACHY/Envisat, which provides daily limb and nadir observations from 2002 to 2012. Beginning in mid-2008, a special limb observation mode for the investigation of the MLT was performed. This data set was used to retrieve the number densities of Mg, Mg , and Na from 2008-2012. Therefore, an existing retrieval algorithm for Mg and Mg was significantly improved and also extended for application in the visible spectral region for Na. The improved retrieval algorithm and the results for Mg, Mg and Na are presented and discussed in this thesis, and the metal's interaction with polar mesospheric clouds is investigated. Furthermore, a survey of spectral signatures of other target species for the retrieval algorithm has been carried out. The measurements have been compared with model results, which include the total daily meteoric mass influx as well as other measurement results. The seasonal, altitudinal and latitudinal variation of metal species is in good agreement with the most recent model results.

Oxygenic photosynthesis is responsible for virtually all of the biochemical production of organic matter, and regulates atmospheric carbon dioxide and oxygen concentrations, which profoundly affects both climate and biogeochemical cycles. Observations of biomass, health and productivity of ocean and land ecosystems are crucial for monitoring changes in the Earth system. Here, space-borne hyperspectral data, mainly of the SCIAMACHY instrument (onboard ENVISAT), have been investigated in terms of application to globalobservations of marine and terrestrial primary producers. This study focuses primarily on retrieving inelastic processes from the natural waters: CDOM and chlorophyll (chl) a fluorescence. Originally, the chl a fluorescence retrieval was developed in its red peak and for the ocean application only. However, it was further extended to the far-red peak of chl a fluorescence, and subsequently applied to terrestrial scenes. All retrievals are based on the Differential Optical Absorption Spectroscopy (DOAS), and involve fitting spectral features of the filling in of the Fraunhofer lines by fluorescence processes. The reference spectra of chl a and CDOM fluorescence, used in the DOAS fits, were calculated with the ocean-atmosphere coupled radiative transfer model SCIATRAN. Furthermore, a simple algorithm to retrieve a chl proxy of terrestrial vegetation was developed. The retrievals were developed with the use of simulated radiances, and subsequently applied to SCIAMACHY data. Although the original aim of the SCIAMACHY instrument was to monitor atmospheric composition, its unique spectral characteristics (namely broad spectral range from 240 nm to 2380 nm, and high resolution of 0.2 nm to 1.5 nm) have enabled previously other novel retrievals to be developed. These included observations of inelastic processes (rotational and vibrational Raman scattering), and marine phytoplank- ton. In this thesis, the chl a fluorescence and chl proxy retrievals were applied to eight years of the SCIAMACHY data (2004-2011). In addition to presenting yearly composites and monthly climatologies of the obtained results, monthly averages were applied to study the seasonality of both, marine phytoplankton and terrestrial vegetation. Modeling studies of CDOM fluorescence, followed by preliminary retrievals applied to SCIAMACHY data, have not been successful in retrieving CDOM fluorescence from hyperspectral satellite data. On the other hand, the obtained chl a fluorescence results showed good spatial agreement with other datasets. Marine observations of the red peak of chl a fluorescence captured successfully the phytoplankton seasonal cycles and interannual variability for two studied regions: a subregion of the Indian Ocean near Madagascar, and the equatorial Pacific. Good agreement with multispectral ocean color products (MODIS nFLH and MODIS Chl a) was obtained. Response of phytoplankton to climate fluctuations, as expressed by Multivariate ENSO Index, was observed for the equatorial Pacific. In case of land observations, all retrieved parameters (red and far-red chl a fluorescence, and chl proxy) followed the seasonal cycles of vegetation for five regions representing different biomes worldwide (croplands in the North America, evergreen needleaf forest in Euroasia, evergreen broadleaf forest in Central Africa, woody savannas in Central Africa and savannas in Southern Africa). However, the three SCIAMACHY datasets did not show exactly the same seasonal pattern, and their relationship varied over time and among biomes. This proves that the retrieved parameters do not carry the same information on vegetation, and hence suggests that they all should be used simultaneously for observations of vegetation dynamics. The calculated ratio and the difference of the two peaks of chl a fluorescence, followed the increase of chl content and canopy development, which supports previous findings by in situ measurements and models.The red and far-red chl a fluorescence and chl proxy algorithms have enabled simultaneous retrievals of multiple parameters of marine phytoplankton and terrestrial vegetation. While the application of the SCIAMACHY results is still constrained (mainly by the noisiness of the results and spatio-temporal resolution of the satellite measurements), the developed retrievals and their successful application to studies of ocean and land phenology have advanced the prospects of observations of phytoplankton and terrestrial vegetation with hyperspectral satellite instruments.

Monitoring of the atmospheric composition of the Earth is essential for studying the processes occurring in different layers of the atmosphere and, consequently, for air quality control and the climate change prediction. The most important conclusions are based on the data from the long-term global observations. Nowadays this data is coming from both space- or airborne instruments and ground based monitoring networks. The ozone (O3) and the methane (CH4) are among the most important trace gases. They play crucial role in the physical and chemical processes in the atmosphere, like formation of the protective stratospheric ozone layer or contribution to the greenhouse effect by absorption of the solar radiation (by both ozone and methane) or radiation re-emitted by the Earth s surface. Another important factor is that both ozone and methane concentration and distribution changes serve as the important markers of the anthropogenic influence on the environment. The atmospheric composition is derived after processing the spectra acquired by the satellite-borne instruments. Most methods utilize the fitting of the observed and synthetic spectra. Modelled spectra are produced based on the preliminary assumptions of approximate concentrations, temperatures and altitude distribution of the trace gases. These methods require a precise knowledge of the electromagnetic radiation absorption characteristics of the different atmospheric gases in a wide spectral range, as well as the temperature and pressure dependences of these parameters. The uncertainties in these tabulated spectral data lead to the uncertainties in the resulting retrieved concentrations and distribution profiles of atmospheric gases. Most of the modern instruments operate in the ultraviolet, visible and infrared parts of the spectrum between 250 nm and 1000 nm for ozone observations. For methane detection, infrared regions of the spectrum around 1,6 or 2,4 micron are mostly used. Despite the fact that different research groups have been analysing the absorption spectra of both ozone and methane with a lot of scrutiny for decades, there still is a room for improvement of the quality of the data. Consequently, the new detailed spectroscopic data would allow to further increase the quality of the atmospheric observations. Demand for an updated and improved (in terms of uncertainties and parameterization capabilities) spectroscopic data for ozone and methane from the remote sensing community was a major motivating factor for this study. This work is dedicated to the acquisition of the new high-quality broadband absorption spectra of ozone and methane, corresponding data analysis and the methods of achieving these goals.

Nitrogen oxides (NOx) play key roles in atmospheric chemistry, air pollution, and climate. While the largest fraction of these reactive gases is released by anthropogenic emission sources, a significant amount can be attributed to vegetation fires. Tropospheric nitrogen dioxide (NO2) amounts can be retrieved from ground-based, ship-based, aircraft-based, and satellite-based remote sensing measurements. The focus of this thesis is to analyze such NO2 measurements for the characterization of NOx from open biomass burning and other sources. In the first part of this thesis, satellite measurements of tropospheric NO2 from GOME-2 and OMI as well as fire radiative power (FRP) from the MODIS instruments are used to derive seasonally averaged fire emission rates (FERs) of NOx for different types of vegetation using a simple statistical approach. Monthly means of tropospheric NO2 vertical columns (TVC NO2) are analyzed for their temporal correlation with the monthly means of FRP for a multi-year period. The strongest correlation is found to be largely confined to tropical and subtropical regions, which account for more than 80% of yearly burned area, on average, globally. As atmospheric models typically require values for the amount of NOx being released as a function of time, the retrieved TVC NO2 is converted into production rates of NOx from fire (Pf). By separating the monthly means of Pf and FRP according to land cover type, FERs of NOx could be derived for different biomes and regions. The estimated FERs for the dominating types of vegetation burned are lowest for boreal forest, open shrublands, and savannas (0.25-1.03 g NOx s^-1 MW^-1) and highest for croplands and woody savannas (0.82-1.56 g NOx s^-1 MW^-1). This analysis demonstrates that the strong empirical relationship between TVC NO2 and FRP and the following simplified assumptions are a useful tool for the characterization of NOx emission rates from vegetation fires in the tropics, subtropics, and in boreal regions. As current fire emission inventories apply emission factors (EFs) of NOx for the translation of biomass burned into trace gas emissions, the satellite-derived FERs of NOx are converted into EFs of NOx. A comparison with NOx EFs found in the literature shows good agreement for some biomes (e.g. boreal forest, tropical forest, and crop residue). However, the EFs for savanna and grassland obtained from satellite measurements are lower by a factor of 2.5. This has possible implications for future work in this field, in particular because savanna and grassland is the most frequently burned biome on Earth. As recent satellite-based studies have indicated substantial spatio-temporal variations in NOx EFs for several biomes, a modified approach is used for the computation of monthly resolved FERs of NOx. In order to evaluate the impact when such seasonal changes are not included, a case study for the African continent to estimate total NOx emissions from open biomass burning is performed by applying both seasonally averaged and monthly resolved FERs of NOx. The results indicate differences between the two tested approaches of up to 90%, in particular on a monthly basis. In the second part of this thesis, ship-based MAX-DOAS measurements performed within the SHIVA campaign in November 2011 on board RV Sonne in the South China and Sulu Sea are analyzed. Spectral measurements for a total of eleven days are used to retrieve tropospheric slant column densities (SCDs) of NO2 and sulfur dioxide (SO2) in the marine environment. An improved NO2 fit including a cross section for liquid water and an empirical correction spectrum accounting for the effects of liquid water and vibrational Raman scattering and a novel SO2 fit are applied to the ship-based measurements. The conversion of SCDs into TVC NO2 is achieved using both a simple geometric approach and the Bremian advanced MAX-DOAS Retrieval Algorithm (BREAM), which is based on the optimal estimation method and accounts for atmospheric radiative transfer. The results show that the geometric approach using the 15 deg measurements is in good agreement with BREAM, revealing that measurements at 15 deg elevation angle can be used for retrieving TVC NO2 in tropical marine environments. As expected, the values of TVC NO2 are generally low (< 0.5 x 10^15 molec cm^-2) when no sources of NOx were in proximity to the RV Sonne. However, increased values of TVC NO2 (> 2 x 10^15 molec cm^-2) are observed in the morning when the RV Sonne was heading along the coast of Borneo. This is in good agreement with satellite measurements. Interestingly, elevated tropospheric SO2 amounts for measurements taken in a busy shipping lane are consistent with the time series of tropospheric NO2.

Tropospheric ozone (O3 ), has two main sources: transport from the stratosphere and photochem- ical production in the troposphere. It plays important roles in atmospheric chemistry and cli- mate change. Its amount and destruction are being modified by anthropogenic activity. Global measurements are needed to test our understanding of its sources and sinks. This dissertation presents a unique method for retrieving tropospheric O3 columns (TOCs) from a global satellite data set. The method involves the combination of limb and nadir observations (hereinafter referred to as limb-nadir-matching (LNM)) of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument, which flew onboard the European Space Agency (ESA) satellite Envisat (2002 - 2012). The LNM technique involve the subtraction of the stratospheric O3 columns (SOCs), retrieved from the limb observations, from the total O3 columns (TOZs), derived from the nadir observations to yield the TOCs

This thesis contributes to the understanding of the temporal evolution of stratospheric ozone as well as bromine monoxide, which is an ozone-depleting substance, during the decade 2002-2012. It is based on data from the satellite instrument SCIAMACHY on board of the European research satellite ENVISAT (2002-2012). Vertically resolved time series of ozone and bromine monoxide are investigated. A comprehensive trend analysis is performed using the concept of linear changes/trends. Long-term changes exhibited by the time series are identified and quantified. They are confirmed by instrument comparisons between SCIAMACHY and other measurements. Consistent with a decline of the stratospheric halogen load, decreases of BrO were found throughout the lower stratosphere. Increases of ozone in the upper stratosphere support the onset of an ozone recovery. In addition, an increase in the lower stratosphere as well as a pronounced decrease in the middle stratosphere were detected in tropical ozone. This co-occurrence of positive and negative changes was, until recently, a rather unexpected phenomenon.

The quantification of emissions of the greenhouse gases carbon dioxide (CO2) and methane (CH4) is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. The current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of CO2 and CH4 is the optical remote sensing instrument MAMAP, operated from aircraft. With a ground scene size of the order of 50m and a relative accuracy of the column-averaged dry air mole fractions of about 0.3% for XCO2 and less than 0.4% for XCH4, MAMAP can make a significant contribution in this respect. Detailed sensitivity studies showed that the modified WFM-DOAS retrieval algorithm used for MAMAP has an approximate accuracy of about 0.24% for XCH4 and XCO2 in typical atmospheric conditions. At the example of CO2 plumes from two different power plants and CH4 plumes from coal mine ventilation shafts, two inversion approaches to obtain emission rates were developed and tested. One is based on an optimal estimation scheme to fit Gaussian plume models from multiple sources to the data and the other is based on a simple Gaussian integral method. Compared to CO2 emission estimates as reported by the power plants' operator within the framework of emission databases (24 and 13 MtCO2/yr), the results of the individual inversion techniques were within plus/minus 10% with uncertainties of plus/minus 20-30% mainly due to insufficient wind information and non-stationary atmospheric conditions. Measurements at the coal mine included on-site wind observations by an aircraft turbulence probe that could be utilised to calibrate the wind model. In this case, the inversion results have a bias of less than 1% compared to the reported CH4 emissions (50 ktCO2/yr) with an uncertainty of approximately plus/minus 13.5%. In cases where no elevated CO2 or CH4 is observed, MAMAP data are useful to provide upper limit constraints as was shown for a marine gas seep. The inversion techniques developed in this work have the potential to provide the basis for quantification and independent validation of anthropogenic and natural point source emission rates. These concepts are not restricted to airborne applications and are of particular value also for future satellite remote sensing missions.

Atmospheric aerosol plays a critical role for human health, air quality, long range transport of pollution, and the Earth s radiative balance, thereby influencing global climate change. To test our scientific understanding and provide an evidence base for policymakers, long-term temporal changes of local, regional, and global aerosols are needed. Remote sensing from satellite borne and ground based observations offers unique opportunities to provide such data. However, only a few studies have discussed the limitations, associated with unrepresentative sampling originating from large/persistent cloud disturbance and limited/different sampling (limited orbital periods and different sampling times) in the trend analysis. Using a linear weighted model, the long-term trends of global AOTs from various polar orbiting satellites and ground observations: MODIS (aboard Terra), MISR (Terra), SeaWiFS (OrbView-2), MODIS (Aqua), and AERONET have been analyzed. In this manner, the present study attempts to minimize the influence of unrepresentative sampling in the trend analysis. Throughout terrestrial and marine regions, temporal increase of cloud-free AOTs were dominat over the globe (GL), northern (NH), and southern hemisphere (SH) (up to 0.00348±0.00185 for GL, 0.00514±0.00272 for NH, and 0.00232±0.00124 per year for SH). Generally, consistently in all observations, the weighted trends over Eastern US and OECD Europe showed a strong decreasing AOT (up to -0.00376±0.00174 for Eastern US and -0.00530±0.00304 per year for OECD Europe) attributed to the recent environmental legislation and resulting regulation of emissions. A significant increase was observed over Saharan/Arabian deserts, South, and East Asia (up to 0.00618±0.00326, 0.01452±0.00615, and 0.01939±0.00986 per year, respectively). These in part dramatic increases are caused by the enhanced amount of aerosol transported/emitted from industrialization, urbanization, deforestation, desertification, and climate change. Overall large/persistent cloud disturbance all year round and the limited/different sampling of polar orbiting satellites represent a challenge, which has been addressed successfully in this study for the accurate determination of aerosol amount and its trends.

The Western Pacific is considered to be the main region where tropospheric trace gases enter the stratosphere. However, the composition of the Western Pacific atmosphere is not well known and the processes driving the transport of tropospheric trace gases into the stratosphere are not fully understood. In this study the composition of the Western Pacific atmosphere is analyzed based on atmospheric measurements performed aboard research vessel Sonne in autumn 2009. The observations are compared to the 3-D chemistry-transport model GEOS-Chem to test the current understanding of Western Pacific air composition. The causes of the observed contamination are analyzed using GEOS-Chem tagged-tracer simulations and trajectory-based transport studies. Finally, the lifetimes of several tropospheric trace gases in this region are calculated to analyze the significance of these gases for troposphere to stratosphere transport.

Aerosols in the Arctic cause radiative forcing and a variety of climatic feedbacks, which affect climate of both local and global scales. In order to assess the state of the Arctic climate, information on the aerosol type and amount is needed. Harsh conditions and remoteness of the Arctic region result in very few ground based measurements of aerosol optical thickness. Remote sensing has the potential to provide the necessary temporal and spatial coverage. A non-trivial task of aerosol retrieval over a very bright surface is being solved within the thesis; the developed retrieval consists of cloud screening over snow and two types of aerosol retrieval over snow - in the visible and infrared spectral regions. A number of validation and case studies has been performed to assess the quality of the retrieval. The developed algorithm applies to the data of Advanced Along Track Scanning Radiometer and produces maps of aerosol optical thickness over snow and ice.

Recent studies have shown the importance of very short-lived substances (VSLS) for the abundance of stratospheric bromine. In this work, the transport of bromine VSLS into the stratosphere is investigated with a three-dimensional chemistry transport model. The novelty of this approach is the explicit treatment of convective transport in a purely isentropic model, a key prerequisite for the realistic reproduction of the complex interplay of horizontal advection, local deep convection and large-scale diabatic heating in the tropical tropopause layer. Comparisons with observations show that the model is generally able to produce realistic distributions of the two major bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). In addition, an analysis of the regional transport efficiency suggests that the Western Pacific is the most important source area for VSLS into the stratosphere; approximately 50% of the total amount of bromine VSLS in the TTL is contributed by this region. Another important question is how dehydration in the tropical tropopause impacts on stratospheric bromine loading. An idealized modeling approach assuming total solubility for inorganic bromine predicts that about 60% of bromine originated from VSLS is able to reach the stratosphere, which is consistent with earlier modeling approaches that use a comparable simple dehydration mechanism. However, when applying a more complete chemistry scheme the model results show that virtually the entire amount of bromine contributed by VSLS enters the stratosphere, rendering the impact of dehydration and scavenging on inorganic bromine insignificant in the TTL. This discrepancy is mainly caused by the low fraction of actually soluble inorganic bromine, the small available particle surface area density that restricts adsorption and finally heterogeneous reactions which are able to release adsorbed species into gas phase. Long-term calculations of VSLS injection into the stratosphere reveal a robust correlation between sea surface temperature, convective activity and the amount of short-lived source gases in the TTL, which becomes especially clear during the perturbations induced by El Nino seasons. Finally, the impact of additional bromine originated from VSLS on stratospheric ozone depletion is analyzed. The model predicts that for 5 parts per trillion by volume (pptv) of bromine contributed by VSLS on average about 1.3% of global total column ozone is destroyed.

Consistent observation-based data sets of stratospheric ozone are needed in order to resolve many of the pending questions regarding stratospheric ozone. Satellite observations are available since the late 1970s; however, as most observational methods rely on backscattered sunlight, these do not provide complete long-term coverage of the stratosphere, in particular during polar night. In this PhD thesis, a 29 year data set of stratospheric ozone is introduced that has been generated from sequential assimilation of satellite observations into the Bremen 3D Chemistry Transport Model (CTM). In the method of data assimilation, a three-dimensional physical computer model is used to close the gaps between single measurements. Observations constrain the CTM where available, and at the same time the information is propagated into areas where no observations are available. Here, profile ozone observations from the Solar Backscatter UV (SBUV and SBUV/2) instruments are used, which have been in orbit continuously since 1978. The resulting assimilated data set is validated against independent observations from other satellite platforms and in-situ observations with sondes. Agreement to independent observations is excellent throughout most of the stratosphere, and the assimilated data set can thus be used as a consistent extension of the satellite record beyond the limits of data coverage. The assimilated data set, in conjunction with sensitivity calculations with the unconstrained CTM, is used to analyse the variability of stratospheric ozone during the last three decades on two distinctly different temporal and spatial domains. The first research question deals with the short-term variability of polar ozone during winter. The Arctic ozone layer is subject to large inter-annual variations during spring; although statistical connections between dynamical quantities in winter and springtime total ozone abundance are known, little is known about how ozone anomalies develop and evolve in winter. With its coverage of polar latitudes during winter, the assimilated data set is ideally suited to address this issue. It is shown that ozone anomalies usually originate in the mid- to upper stratosphere and subsequently descend to the lower stratosphere, displaying a long lifetime of around six months. Ozone anomalies are strongly interrelated to anomalies in the stratospheric circulation, expressed here by the Northern Hemisphere Annular Mode (NAM). Extreme phases of the NAM, so-called strong and weak vortex events, lead to the formation of large and distinctively shaped ozone anomalies that traverse most of the stratosphere within days to weeks, and subsequently remain significant for five months in the lowermost stratosphere. A deeper analysis reveals that different mechanisms of interaction between chemistry and dynamics lead to the observed ozone anomaly pattern. Another source of mid-stratospheric Arctic ozone anomalies is the precipitation of energetic particles from the sun. Solar proton events lead to the formation of nitrogen oxides in the upper stratosphere and mesosphere that subsequently propagate down into the polar vortex and cause significant negative ozone anomalies lasting for up to six months in the assimilated data set. In a second research question, the long-term evolution of ozone is analysed on a global basis. Stratospheric ozone showed large declines during the 1980s and 1990s in both hemispheres. As a consequence of the regulation of ozone depleting substances (ODSs) by the Montreal Protocol in 1987, stratospheric chlorine loadings have peaked in the late 1990s and since begun to slowly decrease. A levelling off of negative ozone trends has been detected, raising the question whether this is already an onset of chemical recovery. The long-term evolution of column ozone is captured very well in the assimilated data set and the unconstrained CTM. Sensitivity calculations with the unconstrained CTM allow for a diligent attribution of observed ozone trends to their processes of origin. In particular, the relative contributions of anthropogenic (emissions of ODSs) and natural (changes in stratospheric circulation and temperature) factors are quantified. While a large part of ozone decreases in the 1980s and 1990s is attributable to ODS increases, only very small effects of chemical recovery are seen after the ODS turnaround. A significant trend change is observed between the phases of increasing and decreasing ODS loadings; however, this trend change is partly related to dynamics, and hence cannot yet be taken as significant evidence for an onset of ozone recovery in most regions.

Within the PhD thesis calibrated observatories for ground-based solar absorption measurements using Fourier transform spectrometers have been established at Bialystok (Poland) and Orléans (France). These two sites are among the most important in-situ sites for greenhouse gas observations in Europe. The on-site combination of vertically resolved in-situ measurements (tall towers and regular aircraft profiling) and remote sensing measurements (FTS) is unique in Europe and vital for the integration of spaceborne and ground-based remote sensing measurements into the European observing system for greenhouse gases. The PhD work included significant involvement in the construction and automation of the two mobile FTS systems, a side by side comparison of two ground-based FTS instruments, the calibration of European FTS sites against in-situ calibration standards, and the initial comparison of the Bialystok FTS dataset with collocated in-situ measurements as well as model simulations.

Carbon monoxide (CO) plays an important role in the Earth's atmosphere. Through its reaction with the hydroxyl radicals (OH) (Logan et al., 1981), CO affects the lifetime of atmospheric methane (CH4), and non-methane hydrocarbons (NMHCs). A main product of this oxidation is carbon dioxide (CO2). Therefore, containing no direct green-house potential, CO still has an indirect effect on the global warming. CO is also one of the most important health hazardous pollutants, which can cause diseases of different degrees of complexity. The nadir near-infrared measurements of scattered and reflected solar radiation by SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument on board the ENVISAT satellite contain information about CO concentration in all atmospheric layers including the boundary layer, closest to the location of main CO sources. However, the retrieval of CO total column from the radiometric measurements in this spectral region is complicated as the CO overtone lines are weak, and overlapped by strong absorptions of water vapour and methane. Moreover, several known instrumental issues, like an ice layer on the detector and degradation of the detector pixels with time, additionally complicate the retrieval of CO vertical column from the of SCIAMACHY measurements in channel 8. In the scope of this work, the WFM-DOAS (Weighting Functions Modified Differential Optical Absorption Spectroscopy) retrieval algorithm, developed at the University of Bremen, have been improved in order to establish the retrieval of a multi-year CO dataset from SCIAMACHY nadir measurements. The modifications have led to an improved CO fit quality, i.e., to an overall much smaller fit residual. An error analysis and sensitivity studies based on the simulated measurements have shown that the error is generally less than 10%, which is comparable to the required precision for space-based CO measurements. However, due to high instrument noise, the error of the real measurements has been found to be much higher and considerably less stable. The retrieved CO columns have been validated by comparison with ground-based Fourier Transform Spectroscopy (FTS) measurements. A good agreement within 10-20% was found for nearly all considered stations. Furthermore, high correlation between the SCIAMACHY CO and CO from independent space-based total columns measurements performed by the MOPITT (Measurements of Pollution in the Troposphere) instrument onboard the Terra satellite indicates a good performance of the SCIAMACHY CO measurements globally. The overall difference of about 10% can be well explained by the moderate sensitivity of the thermal-infrared MOPITT measurements to lower atmospheric layers.Detailed analysis of the obtained CO dataset has been has been carried out on country level. Due to the presence of strong anthropogenic sources and prevailing west wind conditions, a positive difference of CO concentration is expected from the west to the east side of the United Kingdom. The analysis shows that SCIAMACHY is able to capture the positive 5% west-to-east CO gradient over the UK. These results are consistent with the direct airborne measurements during the AMPEP campaign, which estimated the CO concentration enhancement from the west to the east coast of the UK to be about 10-100 ppb, corresponding to the total column enhancement of 1-10% within the 1 km boundary layer. Over much stronger sources, such as a large biomass burning events, the quantitative potential of SCIAMACHY CO data is expected to be much higher due to much higher levels of CO signal and respectively more available ("good") satellite measurements. To use this fact for further quantitative investigation, the SCIAMACHY simultaneously measurements of CO, nitrogen dioxide (NO2) and formaldehyde (HCHO) over biomass burning events in 2004, were analysed in the scope of the bottom-up emission estimation Excess Mixing Ratios (EMR) method. Good agreement has been found between the calculated SCIAMACHY (Delta CO)/(Delta HCHO) and (Delta CO)/(Delta NO2) and the ER values from referenced literature.

Ozone is one of the most publicly discussed atmospheric trace gases since the discovery of the ozone hole over Antarctica in the mid 1980s. The purpose of this thesis is to investigate the solar influence on ozone of the middle atmosphere, with the focus being on variations on small time scales of less than a month. On the one hand the modulating nature of the 27-day solar rotation signal on stratospheric ozone using a new ozone profile data set from SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) is studied. In this context, common and new frequency analysis techniques help to unravel dominant signals. On the other hand data from the latest version 1.07 Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) tropical ozone (1.27 micrometer as well as the 9.6 micrometer retrieval) and temperature data are studied with respect to daytime variations in the upper mesosphere.The frequency analysis of the 27-day solar rotation signal in SCIAMACHY ozone data (< 20_ latitude, 20-60 km altitude, 2003-2008) was carried out with the help of commonly used tools, like the fast-Fourier transform (FFT) and cross-correlation (CC), but was also supplemented with the continuous wavelet transform (CWT), which was not used before in the analysis of satellite ozone data. The CC showed that the maximum correlation between the Mg II index (used in this thesis as solar proxy) and ozone is weaker during the maximum of solar cycle 23 (r = 0.38) than in the previous two solar cycles that have been investigated in earlier studies using different data sets. The magnitude of the ozone signal is highly time dependent and may vanish for several solar rotations even close to solar maximum conditions. The FFT analysis reveals, besides the 27-day signal, several frequencies close to 27-days. The ozone sensitivity (i.e. ozone change in % per 1 % change in 205 nm solar flux) is on average about 0.2 %/% above 30 km altitude and smaller by about a factor of two compared to earlier studies. For selected three month periods the sensitivity may rise beyond 0.6 %/% in better agreement with earlier studies. The analysis of the 27-day solar rotation signal was also carried out with stratospheric European Centre for Medium range Weather Forecast (ECMWF) temperature data from the operational analysis covering the same period as the SCIAMACHY data (2003-2008). Although direct radiation effects on temperature are weak in the upper stratosphere, temperature signals with statistically significant periods in the 25-35 day range similar to ozone could be found with the applied methods.In addition to the 27-day solar rotation signal, the investigation of the SABER tropical mesospheric ozone and temperature daytime variations was combined with a comparison to the output of the three-dimensional general circulation and chemistry Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA). The results show good agreement for ozone. The amplitude of daytime variations is in both cases approximately 60 % of the daytime mean. During equinox the daytime maximum ozone abundance is for both, the observations and the model, higher than during solstice, especially above 80 km. Furthermore, HAMMONIA output of daytime variation patterns of several other different trace gas species, e.g., water vapor and atomic oxygen, is discussed with respect to the daytime pattern in ozone. In contrast to ozone, temperature data show little daytime variations between 65 and 95 km and their amplitudes are on the order of less than 1.5 %. At last, SABER and HAMMONIA temperatures show significant differences above 80 km in their daytime pattern.

This work describes measurements of the tropospheric halogen species iodine monoxide (IO) and bromine monoxide (BrO) with multi-axis differential optical absorption spectroscopy (MAX-DOAS) at various locations: Svalbard (79 deg N), Andoya (69 deg N), List (55 deg N), Crete (35 deg N), and Maldives (5 deg N). Furthermore, the radiative transfer model SCIATRAN was used to investigate the sensitivity of the MAX-DOAS technique towards tropospheric absorbers as well as to estimate concentrations of IO and upper limits only for BrO. IO was detected at Svalbard, List, and Maldives with concentrations of 0.4 ppt, 2.2 ppt, and 2.8 ppt, respectively, but was below the average detection limits of 0.6 ppt and 1.3 ppt for Andoya and Crete, respectively. Uncertainties are estimated to be in the range of 2-3 ppt. These concentrations are averaged horizontally as well as vertically assuming a well-mixed surface layer of 500 m thickness or in the case of Svalbard and List 200 m. On a local scale, higher concentrations can occur. Tropospheric BrO could not be measured at any location outside the polar spring. Minimum detection limits for BrO were 2.2 ppt. Ground-based zenith-sky DOAS measurements of stratospheric chlorine dioxide have been performed at the Arctic sites Svalbard and Summit (73 deg N) as well as at the mid-latitudinal site Bremen (53 deg N) and used to validate SCIAMACHY OClO data for the exceptionally cold stratospheric spring 2005. OClO was also derived with a chemical stacked box model. The agreement of all three data sets is excellent for the time of overpass of the satellite instrument, i.e. 10 AM. However, the ground-based measurements could not be reproduced with the model simulations for large solar zenith angles as well as for large concentrations. Sensitivity studies have been performed with the chemistry model and this exercise demonstrated that the measured OClO columns cannot be explained within the known uncertainties of the model parameters including the involved photochemical data.

Atmospheric columns of the trace gas iodine monoxide, IO, have been investigated by means of spectroscopic measurements in the visible wavelength range. For this purpose, solar radiation scattered and reflected by the Earth's atmosphere and surface is recorded by satellite instrumentation in nadir viewing geometry. These spectra have been analysed for the absorption signal of the IO vibronic absorption lines. Employing the Sciamachy sensor mounted on the ENVISAT satellite, global observations of IO from space become possible for the first time. The importance of iodine in the atmosphere lies in its high potential for destroying ozone as well as in the formation of new particles which is initiated by condensable iodine oxides and may impact on Earth's radiation budget at least locally. A major challenge in this work is the smallness of the observed IO optical depths with respect to the instrument's detection limit. The retrieved IO slant columns are therefore averaged over certain time periods of typically several months. Widespread enhanced IO columns have been detected over the Antarctic region with a detailed spatial and temporal distribution. Further regions with positive IO detection are the Eastern Pacific upwelling region and some Northern Hemispheric coast lines. Additional data such as tropospheric BrO distributions, ice concentrations, phytoplankton amounts and diatom abundances have been considered in specific cases for comparison and discussion purposes, addressing the question of sources of atmospheric iodine, which are most probably biogenic. Successful comparison and validation studies provide confidence in the newly developed satellite IO product, and model calculations have been conducted to investigate the amounts of precursors necessary for the explanation of observed IO abundances. While in some analyses, the limitations of the satellite measurements have been encountered, the presented investigations have advanced the prospects of remote sensing from space for the detection of the minor trace gas IO.

Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides a long-term global data set spanning more than 12 years with the potential of extension up to 2020 by GOME-2 data on MetOp. Using linear and non-linear methods from time series analysis and standard statistics the trends of water vapour columns and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the variance of the noise and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes from -5 % per year to 5 % per year. These significant trends are distributed over the whole globe. Increasing trends have been calculated for Greenland, East Europe, Siberia and Oceania, whereas decreasing trends have been observed for the northwest USA, Central America, Amazonia, Central Africa and the Arabian Peninsular. The idea of the comprehensive trend and significance analysis is to get evidence for the truth of these observed changes. While the significance estimation is based on intrinsic properties such as the length of the data sets, the noise and the autocorrelation, an important aspect of assessing the probability that the real trends have been observed is a validation with independent data. Therefore an intercomparison of the global total column water vapour trends retrieved from GOME and SCIAMACHY with independent water vapour trends measured by radiosonde stations provided by the Deutsche Wetter Dienst DWD (German Weather Service) is presented. The validation has been performed in a statistical way on the basis of univariate time series. Information about the probability of agreement between the two independently observed trends, conditional on the respective data, is revealed. On the one hand a standard t-test is used to compare the trends and on the other hand a Bayesian model selection approach has been developed to derive the probability of agreement. The hypothesis of equal trends from satellite and radiosonde water vapour data is preferred in 85 % of compared pairs of trends. Substantial evidence for the hypothesis of agreeing trends is found in 26 % of analysed trends. However, also disagreement has been observed, where the main reason has been identified on the one hand as the different spatial resolutions of the instruments. This means, that the radiosonde measurements can resolve very localised events, which is not possible with the satellite instruments. On the other hand, in contrast to the in principle continuously available (on a monthly mean basis) GOME/SCIAMACHY data, missing data in the radiosonde time series lead to trend discrepancies. The identification and validation of water vapour trends is an important step for a better understanding of climate change, but water vapour is not the only contributing quantity. Beside water vapour, decisive parameters are temperature, clouds, precipitation, vegetation and many more. A promising framework for the investigation of a multivariate data set of environmental variables is given by the Markov chain analysis. As a first approach, the Markov chain analysis has been applied to a bivariate water vapour -- temperature data set, where the global near surface temperatures are provided by the Goddard Institute of Space Studies (GISS) and cover a time span from 1880 to 2005. The temperature data are retrieved from ground stations and are mainly based on the Global Historical Climatology Network (GHCN). In the framework of a Markov chain analysis, the bivariate set of data is reduced to a univariate sequence of symbols, which can be described as a discrete stochastic process, a Markov chain. This Markov chain represents the water vapour -- temperature interaction or state of a region. Several descriptors have been calculated, such as persistence, replacement of and entropy. This approach is new in environmental science. Exemplarily two climate systems, the Iberian Peninsular and a region at the islands of Hawaii in the central Pacific Ocean, are investigated. The Markov chain analysis is able to retrieve significant differences between the two climate systems in terms of the characteristic descriptors, which reflect properties such as climate stability, rate of changes and short term predictability.

Retrieving aerosol properties from space-borne platforms above deserts, where the surface reflectance is usually very bright, is a challenging problem. The contribution of surface to TOA (Top-Of-Atmosphere) reflectance can reach values of more than 90%, especially for wavelengths above 500 nm. For this reason, detailed knowledge of aerosol and surface optical properties from desert regions is required to distinguish atmospheric radiation from radiation resulting from surfaces that are intrinsically bright. Detailed radiative transfer calculations have been done in a sensitivity study within this thesis to yield information about the technical and physical feasibility of distinguishing between aerosol-loaded atmosphere and surface.The main purpose of this work is to establish a retrieval technique that yields information about dust aerosol properties over source regions from satellite data. The basic quantity retrieved from satellite measurements is the Aerosol Optical Thickness (AOT).

Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements are sensitive to concentration changes of the two gases at all altitude levels down to the Earth's surface where the source/sink signals are largest. Three years (2003-2005) of SCIAMACHY near-infrared nadir measurements have been processed to simultaneously retrieve vertical columns of CO2, CH4, and oxygen using the scientific retrieval algorithm WFM-DOAS. The latest version of WFM-DOAS, version 1.0, which was developed within the scope of this thesis, has been significantly improved with respect to its accuracy compared to the previous versions while essentially maintaining its high processing speed. The greenhouse gas columns are converted to column-averaged dry air mole fractions, denoted XCO2 and XCH4, by dividing the greenhouse gas columns by simultaneously retrieved dry air columns. For XCO2 dry air columns are obtained from the retrieved O2 columns. For XCH4 dry air columns are obtained from the retrieved CO2 columns because of better cancellation of light path related errors compared to using O2 columns retrieved from the spectrally distant O2 A-band.The satellite CO2 data set is compared with ground based Fourier Transform Spectroscopy (FTS) measurements and results from the global assimilation system CarbonTracker showing good agreement concerning the annual increase as well as the seasonal cycle over the northern hemisphere. However, for the southern hemisphere, where significantly less data are available for averaging, the amplitude and phase of the seasonal cycle show systematic differences arising partially from the O2 normalisation most likely caused by unconsidered scattering effects due to subvisual cirrus clouds. Based on the error analysis and on the comparison with the reference data it can be concluded that the XCO2 data set can be characterised by a single measurement retrieval precision (random error) of 1-2%, a systematic low bias of about 1.5%, and by a relative accuracy of about 1-2% for monthly averages at a spatial resolution of about 7°x7°. Averaging the retrieved XCO2 over all three years provides elevated CO2 over densely populated and industrialised source regions indicating that strong regional anthropogenic CO2 emissions can be potentially detected from space.The satellite CH4 data set is compared with global model simulations based on the TM5 model optimised versus high-accuracy surface measurements from the NOAA/ESRL network. After accounting for a systematic low bias of circa 2% agreement with TM5 is typically within 1-2%. The single measurement retrieval precision of XCH4 is estimated to be 1.5-1.7%. It is investigated to what extent the SCIAMACHY XCH4 is influenced by the variability of atmospheric CO2 using global CO2 fields from CarbonTracker showing that agreement with TM5 is better for the CarbonTracker CO2 corrected XCH4. In line with other studies higher methane over the tropics is found compared to the model. Tropical methane is also higher when normalising the CH4 columns with retrieved O2 columns instead of CO2. However, the magnitude of the retrieved tropical methane enhancement is sensitive to changes in spectroscopy and possible inaccuracies in the spectroscopic parameters can thus contribute to a potential overestimation of the tropical methane. First inverse modelling results for methane surface fluxes are presented for the year 2004 performed at the European Commission's Joint Research Centre (EC-JRC) by Peter Bergamaschi.

A novel atmospheric methanol (CH3OH) measurement technique (M&M), employing selective gas-phase catalytic conversion of CH3OH to formaldehyde (HCHO) followed by detection of the HCHO product, is developed, tested, and applied for various studies. The effects of temperature, gas flow rate, gas composition, reactor-bed length, and reactor-bed composition on the CH3OH conversion efficiency of iron molybdate catalyst [Mo-Fe-O] were studied. Best results were achieved using a 1:4 mixture (w/w) of the catalyst in quartz sand. Optimal CH3OH to HCHO conversion (>95% efficiency) achieved at a catalyst housing temperature of 345°C and an estimated sample-air/catalyst contact time of

In the first part of this thesis a cw CRD spectroscope is developed and designed in order to implement it into an environment, enabling the subsequent highly accurate measurements of two weak water vapour lines in the close vicinity of strong lines in a wide temperature and pressure range (251-296K, 100-1020 mbar) at about 940 nm. In the second part, the standard parameterisation of absorption spectra is analysed respective to the ability to reproduce the measured spectra depending on the particular temperature and pressure range in a highly accurate manner. As a result, the use of the Voigt profile limits the accuracy to about 3.5%, while the use of the Galatry profile improves the reproducibility in the line core to a part. There is nevertheless evidence for other effects such as line mixing or a variation of the form of the line profile depending on temperature. Additionally, the predictions for the water vapour continuum at 940 nm were confirmed on the basis of laboratory measurements for the first time.

Measurements from the space-borne instrument SCIAMACHY launched in March 2002 onboard the ENVISAT platform, have been analysed for BrO absorption using the Differential Optical Absorption Spectroscopy (DOAS) method. BrO is an important atmospheric trace gas mainly responsible for the depletion of ozone in the polar boundary layer, the free troposphere and the stratosphere. Since 1995, global observations of BrO have been successfully demonstrated by the GOME instrument in several publications. This work reports the retrieval of BrO columns from the channel 2 UV/Visible spectral range of the SCIAMACHY nadir geometry. Although data analysis of GOME and SCIAMACHY BrO is very similar, a UV-shifted spectral range was employed to minimize the impact of residual structures from the polarisation sensitivity of the instrument. From this analysis, excellent agreement was obtained between the GOME and SCIAMACHY BrO columns. The impact of the improved spatial resolution of SCIAMACHY has also been utilised to explore the possibility for a volcanic source of BrO during major eruptions. In the polar regions over sea ice, frost flowers have been implicated as a major source of bromine to the atmosphere and BrO columns obtained from GOME and SCIAMACHY measurements correlates with areas potentially covered with frost flowers.

The focus of this thesis is the evaluation of the first solar occultation measurements performed by SCIAMACHY onboard ENVISAT in the UV-vis-NIR wavelength range. Vertical trace gas concentration profiles have been retrieved from atmospheric measurement spectra, fitting the differential structures of extinction signals. An introduction is given about the foundations of the occultation geometry. The underlying studies are separated into theoretical investigations about the sensitivity of the instrument with respect to atmospheric constituents and trace gas retrievals from the first real measurement data. It is shown that the spectrometer works as expected in occultation geometry. Spectral data have a high signal-to-noise ratio except for the UV wavelength range at low altitudes. First standard data products of ozone and nitrogen dioxide vertical profiles in the stratosphere and upper troposphere have been produced with errors in the order of 10 and 15 %, respectively. The inversion algorithm is based on the optimal estimation method or, alternatively, on the eigenvector decomposition method. Correction algorithms have been implemented concerning the tangent height of the line of sight and the pointing on the solar disk. The radiative transfer model is based on the Lambert-Beer law of extinction. The retrieval algorithm assumes the measured spectra to consist only of transmitted light rather than scattered light. Theoretical studies have been performed to demonstrate that this assumption is true. An estimation of different error sources is discussed as well.

Peroxy Radicals have been measured in different regions in Europe. These different environmentsare characterized by mean or moderate anthropogenic impacts at the lower atmosphere(troposphere). Measurements were performed during the projects FIELDVOC and OCTA in 1993and 1994. The aim of these projects is an improved investigation of tropospheric ozone generation.The first measurements during both campaigns in 1993 were performed using an instrument, whichwas developed at the Max-Planck-Institut für Chmie (Mainz). For the measurements in 1994 theinstrument and the calibration method was improved for operation during field campaigns. Themeasured data are compared with results of a photochemical model to identify the role of Non-Methane-Hydrocarbons and to determine local ozone production.

Retrieval of atmospheric constituents from remote sensing measurements requires a radiative transfer forward model and appropriate inversion algorithms. A fast and accurate correlated-k (c-k) distribution radiative transfer scheme has been developed for the simulation of radiance spectra to be measured in nadir viewing geometry by the SCIAMACHY satellite diode array grating spectrometer. SCIAMACHY is part of the atmospheric sciences payload of the European Space Agencies ENVISAT-1 satellite to be launched in mid 2001. SCIAMACHY covers the spectral region 240-2385 nm with moderate spectral resolution (0.2-1.6 nm FWHM) and observers solar radiation scattered and reflected back to space by the Earths atmosphere and surface. The spectral region 440-2385 nm is dominated by molecular line absorption due to CO, CO2, CH4, H2O, N2O, and O2. The most accurate approach for the calculation of the spectrally averaged radiance - if line absorption needs to be considered - is the line-by-line approach. This approach, however, is very time consuming and can only be used for reference purposes. Therefore, a much faster c-k scheme has been developed. It is based on parameters that can be interpreted as trace gas absorption cross-sections representative for narrows spectral intervals. In this context a new method (alpha-mixing scheme) has been developed to consider spectrally overlapping line absorption. This method is shown to be more accurate (at SCIAMACHY resolution) and flexiblethan any previously developed method. The c-k and a line-by-line schemes have been implemented in the radiative transfer.

Nitrogen oxides (NOx = NO NO2) are a key species in the atmosphere, impacting on human health, tropospheric ozone formation, acid rain and climate. The major source of NOx are combustion processes. The lifetime of NOx in the atmosphere is short. Hence, it is found close to its sources and can serve as a proxy to identify anthropogenic pollution. The distinct spectral features of NO2 enable to retrieve its abundance by remote sensing, using differential optical absorption spectroscopy (DOAS). Spaceborne measurements of trace gases using the DOAS method have been performed for more than two decades and provided new insights on the atmospheric composition on a global and regional scale. Within this work, the DOAS technique is applied to airborne imaging DOAS measurements of the AirMAP instrument, developed at the University of Bremen. As the instrument is operated on an aircraft, the measurements have a much higher spatial resolution than the ones from satellite, due to the lower flight altitude. The aircraft platform provides a tool to gaplessly map the horizontal NO2 distribution at the scale of a large city, such as Berlin, in a time window of about two hours. The derived high resolution trace gas maps reveal spatial patterns in the NO2 distribution that cannot be resolved by the satellite measurements. This thesis presents trace gas maps from research flights covering different target areas, including shipping lanes, power plants and cities at a resolution better than 100 meter. Special efforts were made to increase the accuracy of the measurements by accounting for parameters that affect the atmospheric radiative transfer, such as scattering in the atmosphere and reflection at the surface. The air mass factors, which are needed to convert the measured differential slant column densities (dSCDs) to vertical column densities (VCDs), have a strong dependence on the surface reflectance, which has to be accounted for in the retrieval. This is especially important for measurements above urban areas, where surface properties vary strongly. As the instrument is not radiometrically calibrated, a method was developed to derive the surface reflectance from relative intensities measured by AirMAP. This method is based on radiative transfer calculations with SCIATRAN and a reference area for which the surface reflectance is known. Furthermore, the influence of aerosols on the retrieval was investigated for a variety of aerosol profiles that were measured in the context of the AROMAT campaigns in which AirMAP participated. Validation with independent measurements shows in general good agreement. The measurement datasets created, as well as the methods developed within this work, provide the basis to validate other high resolution datasets, such as regional chemistry models or satellite measurements at high resolution, such as the ones performed by the Sentinel-5p, launched in October 2017.