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The Ozone Monitoring Instrument (OMI) instrument has provided daily global measurements of tropospheric NO2 for more than a decade. Numerous studies have drawn attention to the complexities related to measurements of tropospheric NO2 in the presence of aerosols. Fine particles affect the OMI spectral measurements and the length of the average light path followed by the photons. However, they are not explicitly taken into account in the current OMI tropospheric NO2 retrieval chain. Instead, the operational OMI O2-O2 cloud retrieval algorithm is applied both to cloudy scenes and to cloud free scenes with aerosols present. This paper describes in detail the complex interplay between the spectral effects of aerosols, the OMI O2-O2 cloud retrieval algorithm and the impact on the accuracy of the tropospheric NO2 retrievals through the computed Air Mass Factor (AMF) over cloud-free scenes. Collocated OMI NO2 and MODIS Aqua aerosol products are analysed over East China, in industrialized area. In addition, aerosol effects on the tropospheric NO2 AMF and the retrieval of OMI cloud parameters are simulated. Both the observation-based and the simulation-based approach demonstrate that the retrieved cloud fraction linearly increases with increasing Aerosol Optical Thickness (AOT), but the magnitude of this increase depends on the aerosol properties and surface albedo. This increase is induced by the additional scattering effects of aerosols which enhance the scene brightness. The decreasing effective cloud pressure with increasing AOT represents primarily the absorbing effects of aerosols. The study cases show that the actual aerosol correction based on the implemented OMI cloud model results in biases between ?20 and ?40 % for the DOMINO tropospheric NO2 product in cases of high aerosol pollution (AOT ? 0.6) and elevated particles. On the contrary, when aerosols are relatively close to the surface or mixed with NO2, aerosol correction based on the cloud model results in overestimation of the DOMINO tropospheric NO2 product, between 10 and 20 %. These numbers are in line with comparison studies between ground-based and OMI tropospheric NO2 measurements under conditions with high aerosol pollution and elevated particles. This highlights the need to implement an improved aerosol correction in the computation of tropospheric NO2 AMFs.

We derive a global climatology of tropospheric NO2 profiles from OMI cloudy observations for the year 2006 using the cloud slicing method on six pressure levels centered about 280, 380, 500, 620, 720 and 820 hPa. A comparison between OMI and the TM4 model tropospheric NO2 profiles reveals striking overall similarities, which confer great confidence to the cloud-slicing approach, along with localized discrepancies that seem to probe into particular model processes. Anomalies detected at the lowest levels can be traced to deficiencies in the model surface emission inventory, at mid tropospheric levels to convective transport and horizontal advective diffusion, and at the upper tropospheric levels to model lightning NOx production and the placement of deeply transported NO2 plumes such as from the Asian summer monsoon. The vertical information contained in the OMI cloud-sliced NO2 profiles provides a global observational constraint that can be used to evaluate chemistry transport models (CTMs) and guide the development of key parameterization schemes.

The Nanjing Government has taken temporary environmental regulations to guarantee good air quality during the Youth Olympic Games (YOG) in 2014. We study the effect of those regulations by applying the emission estimate algorithm DECSO (Daily Emission estimates Constrained by Satellite Observations) to measurements of the Ozone Monitoring Instrument (OMI). We improved DECSO by updating the chemical transport model CHIMERE from v2006 to v2013 and by adding an Observation minus Forecast (OmF) criterion to filter outlying satellite retrievals due to high aerosol concentrations. The comparison of model results with both ground and satellite observations indicates that CHIMERE v2013 is better performing than CHIMERE v2006. After filtering the satellite observations with high aerosol loads that were leading to large OmF values, unrealistic jumps in the emission estimates are removed. Despite the cloudy conditions during the YOG we could still see a decrease of tropospheric NO2 column concentrations of about 32% in the OMI observations as compared to the average NO2 concentrations from 2005 to 2012. The results of the improved DECSO algorithm for NOx emissions show a reduction of at least 25% during the YOG period. This indicates that air quality regulations taken by the local government were successful. The algorithm is also able to detect an emission reduction of 10% during the Chinese Spring Festival. This study demonstrates the capacity of the DECSO algorithm to capture the change of NOx emissions on a monthly scale. We also show that the observed concentrations and the derived emissions show different patterns that provide complimentary information. For example, the Nanjing smog episode in December 2013 led to a strong increase in NO2 concentrations without an increase in NOx emissions. Furthermore, DECSO gives us important information of the non-trivial seasonal relation between NOx emissions and NO2 concentrations on a local scale.

Peak stratospheric chlorofluorocarbon (CFC) and other ozone depleting substance (ODS) concentrations were reached in the mid- to late 1990s. Detection and attribution of the expected recovery of the stratospheric ozone layer in an atmosphere with reduced ODSs as well as efforts to understand the evolution of stratospheric ozone in the presence of increasing greenhouse gases are key current research topics. These require a critical examination of the ozone changes with an accurate knowledge of the spatial (geographical and vertical) and temporal ozone response. For such an examination, it is vital that the quality of the measurements used be as high as possible and measurement uncertainties well quantified. In preparation for the 2014 United Nations Environment Programme (UNEP)/World Meteorological Organization (WMO) Scientific Assessment of Ozone Depletion, the SPARC/IO3C/IGACO-O3/NDACC (SI2N) Initiative was designed to study and document changes in the global ozone profile distribution. This requires assessing long-term ozone profile data sets in regards to measurement stability and uncertainty characteristics. The ultimate goal is to establish suitability for estimating long-term ozone trends to contribute to ozone recovery studies. Some of the data sets have been improved as part of this initiative with updated versions now available. This summary presents an overview of stratospheric ozone profile measurement data sets (ground and satellite based) available for ozone recovery studies. Here we document measurement techniques, spatial and temporal coverage, vertical resolution, native units and measurement uncertainties. In addition, the latest data versions are briefly described (including data version updates as well as detailing multiple retrievals when available for a given satellite instrument). Archive location information for each data set is also given., Atmospheric Measurement Techniques, 7 (5), ISSN:1867-1381, ISSN:1867-8548

The ESA (European Space Agency) Sentinel-5 Precursor (S-5 P) is a low Earth orbit polar satellite to provide information and services on air quality, climate and the ozone layer in the timeframe 2015-2022. The S-5 P mission is part of the Global Monitoring of the Environment and Security (GMES) Space Component Programme. The payload of the mission is the TROPOspheric Monitoring Instrument (TROPOMI) that will measure key atmospheric constituents including ozone, NO2, SO2, CO, CH4, CH2O and aerosol properties. TROPOMI has heritage to both the Ozone Monitoring Instrument (OMI) as well as to the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY). The S-5 P will extend the data records of these missions as well as be a preparatory mission for the Sentinel-5 mission planned for 2020 onward. The mission is pre-operational and is the link between the current scientific and the operational Sentinel-4/-5 missions. This contribution describes the science and mission objectives, the mission and the instrument, and the data products. While building on a solid foundation of the heritage instruments, the S-5P/TROPOMI mission is an exciting step forward with a strong focus on the troposphere. This is achieved by a combination of a high spatial resolution and improved signal-to-noise, as well as dedicated data product development. It is anticipated that the S-5 P mission will make a large contribution to the monitoring of the global atmospheric composition, as well as to the scientific knowledge of relevant atmospheric processes. © 2012 Elsevier Inc.

Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) is a technique to measure trace gas amounts in the lower troposphere from ground-based scattered sunlight observations. MAX-DOAS observations are especially suitable for validation of tropospheric trace gas observations from satellite, since they have a representative range of several kilometers, both in the horizontal and in the vertical dimension. A two-step retrieval scheme is presented here, to derive aerosol corrected tropospheric NO2 columns from MAX-DOAS observations. In a first step, boundary layer aerosols, characterized in terms of aerosol optical thickness (AOT), are estimated from relative intensity observations, which are defined as the ratio of the sky radiance at elevation a and the sky radiance in the zenith. Relative intensity measurements have the advantage of a strong dependence on boundary layer AOT and almost no dependence on boundary layer height. In a second step, tropospheric NO2 columns are derived from differential slant columns, based on AOT-dependent air mass factors. This two-step retrieval scheme was applied to cloud free periods in a twelve month data set of observations in De Bilt, The Netherlands. In a comparison with AERONET (Cabauw site) a mean difference in AOT (AERONET minus MAX-DOAS) of -0.01±0.08 was found, and a correlation of 0.85. Tropospheric-NO2 columns were compared with OMI-satellite tropospheric NO2. For ground-based observations restricted to uncertainties below 10%, no significant difference was found, and a correlation of 0.88.

No abstract.

Nitrogen Dioxide (NO2) is an important component of air pollution. It is observed on a global scale by satellite instruments such as GOME, SCIAMACHY and OMI. Worldwide there are only few observation sites where nitrogen dioxide tropospheric columns are monitored on an operational basis. For satellite validation it is essential to perform these ground based measurements with good global and seasonal coverage preferably in a network of similar and intercalibrated instruments. Since November 2007 multiaxis differential optical absorption spectroscopy (MAXDOAS) observations of NO2 are performed on an operational basis at the Royal Netherlands Meteorological Institute (KNMI). For this a Mini MAX-DOAS instrument is used. This relatively low cost instrument could be a candidate for a global network as mentioned above. We will explain the tropospheric column retrieval algorithm which includes a correction for aerosols. The Doubling Adding radiative transfer model is used to create look up tables for the Air Mass Factors as a function of radiation intensity which depends on aerosol optical thickness (AOT) and boundary layer height. In addition we will show results from several studies based on the observations. First: a comparison of retrieved AOT and direct sun observations of AOT from the CESAR site in Cabauw, The Netherlands. Second: an analysis of the retrieved tropospheric vertical columns of NO2 in this highly polluted region. Third: comparison with SCIAMACHY and OMI tropospheric NO2 columns. Finally: first results from the CINDI inter-comparison campaign for NO2 measuring instruments. This campaign has taken place in Cabauw, in June and July 2009. Many different groups have participate in this campaign which had resulted in a variety of simultaneous in-situ and remote sensing observations of NO2, other trace gases and aerosols.

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This is the final report of the CAMELOT (Chemistry of the Atmosphere Mission concEpts and sentineL Observations Techniques) study. The key objective of the CAMELOT study was to contribute to the definition of the air quality and climate protocol monitoring parts of GMES Sentinels 4 and 5 missions. This report presents the conclusions and recommendations of this study, regarding the Sentinel 4 and 5 Level 1B requirements and the mission scenario’s.

Existing algorithms that use satellite measurements of solar backscattered ultraviolet (BUV) radiances to retrieve sulfur dioxide (SO2) vertical columns underestimate the large SO2 amounts encountered in fresh volcanic eruption clouds. To eliminate this underestimation we have developed a new technique, named the Iterative Spectral Fitting (ISF) algorithm, for accurate retrieval of SO2 vertical columns in the full range of volcanic emissions. The ISF algorithm is applied to Ozone Monitoring Instrument (OMI) BUV measurements of the Sierra Negra eruption (Galàpagos Islands, Ecuador) in October 2005. The results represent major improvements over the operational OMI SO2 products. Based on the ISF data, we report the largest SO2 vertical column amount (>1000 Dobson Units (DU), where 1 DU = 2.69 × 1016 molecules/cm2) ever observed by a space borne instrument, implying that very high concentrations of SO2 can occur in the lower troposphere during effusive eruptions.

The growth of human population and the industrialisation in the 19th and 20th century has led to dramatic changes in the Earth System. The chemical composition of the lowest part of the atmosphere, the troposphere, is changing as a result of human activities. The Earth has entered the "Anthropocene" epoch, where the activities of humans play a key role in air quality and climate change. The rapid development of megacities (see Figure 1) and the strong development in the Asian countries are clear examples of rapid changes that affected the atmosphere in the last decades and will continue to do so in the future. For understanding climate change and air quality, global changes in the chemical composition of the troposphere need to be taken into account/addressed. Especially the global inventory of emission sources play a key role in understanding and modelling the troposphere in relation to climate change and air pollution. Also regional and long-range transport of pollution, as well as the rapid development of pollution levels during the day, are important for understanding air quality and climate change and their interaction Atmospheric measurements from space started in the 70th’s with US sensors SBUV[)] and TOMS[2], focussing on the ozone layer residing in the higher layers in the atmosphere. Sensing the lower atmospheric layers from space is a recent development in satellite remote sensing, where SCIAMACHY[[3]] on board ESA’s ENVISAT), OMI[4] on board NASA’s EOS-Aura) and GOME-2[5] (on board METOP-1) instruments play a leading role. Unprecedented measurements from space from OMI reveal tropospheric pollution maps on a daily basis with urban scale resolution. Measurements from Thermal Infrared instruments like MOPITT [6], AIRS[7] , IASI[[8]] and TES[[9]] also provide unique information on the troposphere, providing tropospheric profile information. In this paper an overview will be given of satellite measurements from space of the chemical composition of the troposphere and their role in climate change and air pollution. Also challenges and future developments for tropospheric measurements from space will be discussed, including the Dutch initiative satellite instrument (TROPOMI) for detection of the tropospheric composition.

The TROPOspheric Monitoring Instrument (TROPOMI) is a UV/VIS/NIR/SWIR non-scanning nadir viewing imaging spectrometer that combines a wide swath (110°) with high spatial resolution (8 x 8 km). Its main heritages are from the Ozone Monitoring Instrument (OMI) and from SCIAMACHY. Since its launch in 2004 OMI has been providing, on a daily basis and on a global scale, a wealth of data on ozone, NO 2 and minor trace gases, aeros ols and local pollution, a scanning spectrometer launched in 2004. The TROPOMI UV/VIS/NIR and SWIR heritage is a combination of OMI and SCIAMACHY. In the framework of development programs for a follow-up mission for the successful Ozone Monitoring Instrument, we have developed the so-called TROPOMI Integrated Development Environment. This is a GRID based software simulation tool for OMI follow-up missions. It includes scene generation, an instrument simulator, a level 0-1b processing chain, as well as several level 1b-2 processing chai ns. In addition it contains an error-analyzer, i.e. a tool to feedback the level 2 results to th e input of the scene generator. The paper gives a description of the TROPOMI instrument and focuses on design aspects as well as on the performance, as tested in the end-to-end development environment TIDE. Keywords: TROPOMI, Air Quality, Grid Assist, TIDE, spectrograph

The TROPOMI instrument concept is part of the TRAQ mission proposal to ESA in response to the Call for Ideas in 2005. TRAQ (TRopospheric composition and Air Quality) has been accepted for a further pre-phase A study for the next Earth Explorer core Mission. A very similar instrument has been proposed for the CAMEO platform to the US National Research Council decadal study, which has also been accepted for further study. TROPOMI is a nadir-viewing grating-based imaging spectrometer using the Dutch OMI and SCIAMACHY heritage. It includes an UV-VIS-NIR module that consists of three UV-VIS channels continuously covering the 270-490 nm range to determine O3, NO2, HCHO, SO 2, aerosols and a NIR-channel covering 710-775 nm for cloud detection and information on the aerosol height distribution using the oxygen A band. TROPOMI also includes a SWIR module covering 2305-2385 nm that mainly focuses on determination of CO and CH4 total columns. All species are measured with sensitivity down to the Earth's surface, thus addressing issues of anthropogenic emissions and their impact on air quality and climate. In the TRAQ mission, unique diurnal time sampling with up to 5 daytime observations over midlatitude regions (Europe, North-America, China) is foreseen by using a non-sun-synchronous, medium-inclination drifting orbit and a 2600 km wide observational swath. Several more general aspects related to the TROPOMI instrument are discussed in a separate paper in this conference. This paper focuses on the development of the SWIR module. A breadboard model (BBM) has been designed and constructed which is as much as possible functionally flight representative. Critical technologies to be demonstrated with the BBM are the SWIR HgCdTe-based 2D focal plane array, the on-board SWIR calibration LED, and in particular, the SRON/TNO developed silicon-based immersed grating that allows a hugely reduced instrument volume. In the presentation the results of a performance analysis of the TROPOMI-S WIR channel will be discussed, as well as results of the detector characterization program on a representative off-the-shelf FPA, and details of the photolithographic production of the immersed grating.

We discuss collection 2 SO2 data from the Dutch-Finnish Ozone Monitoring Instrument (OMI) on board NASA EOS/Aura spacecraft and show examples of detected volcanic and anthropogenic SO2 emissions. Quantification of anthropogenic SO2 emissions requires collection 3 reprocessing available in the fall 2007.

TROPOMI is a nadir-viewing grating-based imaging spectrograph in the line of OMI and SCIAMACHY. TROPOMI is part of the ESA Candidate Core Explorer Mission proposal TRAQ and also of the CAMEO satellite proposed for the US NRC decadal study. A TROPOMI-like instrument is part of the ESA/EU Sentinel 4&5 pre-phase A studies. TROPOMI covers the OMI wavelengths of 270-490 nm to measure O3, NO2, HCHO, SO2 and aerosols and adds a NIR channel and a SWIR module. The NIR-channel (710-775 nm) is used for improved cloud detection and aerosol height distribution. The SWIR module (2305 - 2385 nm) measures CO and CH4 and forms a separate module because of its thermal requirements. TROPOMI is a non-scanning instrument with an OMI-like telescope but optimized to have smaller ground pixels (10 × 10 km2) and sufficient signal-to-noise for dark scenes (albedo 2 %). TROPOMI has the same wide swath as OMI (2600 km). In TRAQ's mid-inclination orbit, this allows up to 5 daytime observations over mid-latitude regions (Europe, North-America, China). The paper gives a description of the TROPOMI instrument and focuses on several important aspects of the design, for example the sun calibration and detector selection status. U7 - Export Date: 2 August 2010 U7 - Source: Scopus U7 - Art. No.: 674409

The multi-wavelength retrieval algorithm is used to retrieve aerosol parameters from spectra reflectance measurements of the Ozone Monitoring Instrument (OMI). This retrieval algorithm uses up to 19 wavelength bands between 331 nm and 500 nm including a band at 477 nm comprising an absorption band of O2-O2. This absorption band has been included in order to increase the amount of height information that can be extracted from the measurement. A principal component analysis shows that OMI measurements have 2 to 4 degrees of freedom of signal, which for cloud free scenes can be attributed to aerosol parameters. In the multi-wavelength algorithm the aerosol optical thickness at a reference wavelength is retrieved for a set of aerosol models and the best fitting aerosol model is determined. The aerosol models are determined by the single-scattering albedo, the layer height, and the size distribution. The algorithm is capable to distinguish between absorbing aerosol types, such as desert dust and biomass burning, and weakly absorbing aerosols like sea-salt and sulfates. We show retrieved aerosol parameters for various scenes and conditions. Furthermore we show how height information from space borne lidar instruments (e.g. CALIPSO) can be used in the OMI retrievals. U7 - Export Date: 2 August 2010 U7 - Source: Scopus

In this paper the OMI ozone column measurements obtained with the TOMS-V8 total ozone algorithm are evaluated against OMI ozone columns simulated by means of ozone analyses resulting from assimilation of standard meteorological observations as well as independent ozone retrievals into a numerical weather prediction model. Intercomparison results between measured versus simulated OMI ozone columns at sza

TROPOMI is a nadir-viewing grating-based imaging spectrograph in the line of OMI and SCIAMACHY. TROPOMI is part of the ESA Candidate Core Explorer Mission proposal TRAQ and also of the CAMEO satellite proposed for the US NRC decadal study. A TROPOMI-like instrument is part of the ESA/EU Sentinel 4&5 pre-phase A studies. TROPOMI covers the OMI wavelengths of 270-490 nm to measure O3, NO2, HCHO, SO2 and aerosols and adds a NIR channel and a SWIR module. The NIR-channel (710-775 nm) is used for improved cloud detection and aerosol height distribution. The SWIR module (2305 - 2385 nm) measures CO and CH4 and forms a separate module because of its thermal requirements. TROPOMI is a non-scanning instrument with an OMI-like telescope but optimized to have smaller ground pixels (10 × 10 km2) and sufficient signal-to-noise for dark scenes (albedo 2 %). TROPOMI has the same wide swath as OMI (2600 km). In TRAQ's mid-inclination orbit, this allows up to 5 daytime observations over mid-latitude regions (Europe, North-America, China). The paper gives a description of the TROPOMI instrument and focuses on several important aspects of the design, for example the sun calibration and detector selection status.

We report the first daily observations of sulfur dioxide (SO2) emissions from copper smelters by a satellite-borne sensor - the Ozone Monitoring Instrument (OMI) on NASA's EOS/Aura spacecraft. Emissions from two Peruvian smelters (La Oroya and Ilo) were detected in up to 80% of OMI overpasses between September 2004 and June 2005. SO2 production by each smelter in this period is assessed and compared with contemporaneous emissions from active volcanoes in Ecuador and southern Colombia. Annual SO2 discharge from the Ilo smelter, La Oroya smelter, and volcanoes in 2004–2005 is estimated and amounts to 0.3-0.1 +0.2, 0.07 ± 0.03, and 1.2 ± 0.5 Tg, respectively. This study confirms OMI's potential as an effective tool for evaluation of anthropogenic and natural SO2 emissions. Smelter plumes transport an array of toxic metals in addition to SO2 and continued monitoring to mitigate health and environmental impacts is recommended.

We present a new algorithm for the near-real time retrieval – within 3 h of the actual satellite measurement – of tropospheric NO2 columns from the Ozone Monitoring Instrument (OMI). The retrieval is based on the combined retrieval-assimilation-modelling approach developed at KNMI for off-line tropospheric NO2 from the GOME and SCIAMACHY satellite instruments. We have adapted the off-line system such that the required a priori information – profile shapes and stratospheric background NO2 – is now immediately available upon arrival (within 80 min of observation) of the OMI NO2 slant columns and cloud data at KNMI. Slant columns for NO2 are retrieved using differential optical absorption spectroscopy (DOAS) in the 405–465 nm range. Cloud fraction and cloud pressure are provided by a new cloud retrieval algorithm that uses the absorption of the O2-O2 collision complex near 477 nm. On-line availability of stratospheric slant columns and NO2 profiles is achieved by running the TM4 chemistry transport model (CTM) forward in time based on forecast ECMWF meteo and assimilated NO2 information from all previously observed orbits. OMI NO2 slant columns, after correction for spurious across-track variability, show a random error for individual pixels of approximately 0.7×10¹5 molec cm¿². Cloud parameters from OMI's O2-O2 algorithm have similar frequency distributions as retrieved from SCIAMACHY's Fast Retrieval Scheme for Cloud Observables (FRESCO) for August 2006. On average, OMI cloud fractions are higher by 0.011, and OMI cloud pressures exceed FRESCO cloud pressures by 60 hPa. A sequence of OMI observations over Europe in October 2005 shows OMI's capability to track changeable NOx air pollution from day to day in cloud-free situations.

No abstract.

In this paper we report on the progress achieved within the framework of the joint ESA KNMI NIVR Calibration and Validation Announcement of Opportunity for the Ozone Monitoring Instrument aboard the NASA EOS Aura satellite. This OMI AO effort has rendered a wealth of validation results and scientific insights. Herein this contribution only a selection of the validation results is presented.

Sulfate aerosol produced after injection of sulfur dioxide (SO2) into the stratosphere by volcanic eruptions can trigger climate change. We present new satellite data from the Ozone Monitoring Instrument (OMI) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) missions that reveal the composition, structure and longevity of a stratospheric SO2 cloud and derived sulfate layer following a modest eruption (0.2 Tg total S02) of Soufriere Hills volcano, Montserrat on 20 May 2006. The SO2 cloud alone was tracked for over 3 weeks and a distance of over 20 000 km; unprecedented for an eruption of this size. Derived sulfate aerosol at an altitude of ~20 km had circled the globe by 22 June and remained visible in CALIPSO data until at least 6 July. These synergistic NASA A-Train observations permit a new appreciation of the potential effects of frequent, small-to-moderate volcanic eruptions on stratospheric composition and climate. U7 - Export Date: 2 August 2010 U7 - Source: Scopus

In preparation for future atmospheric space missions a consortium of Dutch organizations is performing design studies on a nadir viewing grating-based imaging spectrometer using OMI and SCIAMACHY heritage. The spectrometer measures selected species (O3, NO2, HCHO, H2O, SO 2, aerosols (optical depth, type and absorption index), CO and CH4) with sensitivity down to the Earth's surface, thus addressing science issues on air quality and climate. It includes 3 UV-VIS channels continuously covering the 270-490 nm range, a NIR-channel covering the 710-775 nm range, and a SWIR-channel covering the 2305-2385 nm range. This instrument concept is, named TROPOMI, part of the TRAQ-mission proposal to ESA in response to the Call for Earth Explorer Ideas 2005, and, named TROPI, part of the CAMEO-proposal prepared for the US NRC decadal study-call on Earth science and applications from space. The SWIR-channel is optional in the TROPOMI/TRAQ instrument and included as baseline in the TROPI/CAMEO instrument. This paper focuses on derivation of the instrument requirements of the SWIR-channel by presenting the results of retrieval studies. Synthetic detector spectra are generated by the combination of a forward model and an instrument simulator that includes the properties of state-of-the-art detector technology. The synthetic spectra are input to the CO and CH4 IMLM retrieval algorithm originally developed for SCIAMACHY. The required accuracy of the Level-2 SWIR data products defines the main instrument parameters like spectral resolution and sampling, telescope aperture, detector temperature, and optical bench temperature. The impact of selected calibration and retrieval errors on the Level-2 products has been characterized. The current status of the SWIR-channel optical design with its demanding requirements on ground-pixel size, spectral resolution, and signal-to-noise ratio will be presented.

The Ozone Monitoring Instrument (OMI) on NASA's AURA satellite is one of the first instruments measuring an extensive set of daily air quality parameters from space. This anwers to a growing interest in obtaining space data for the air we breath next to the higher altitude air masses. OMI combines UV-Visible nadir viewing spectroscopy, small ground pixels and daily global coverage. As SCIAMACHY on ENVISAT, it uses the high sensitivity of UV-Visible spectroscopy to the lowest kilometers of the atmosphere and the boundary layer. It has fairly small ground pixels (13 × 24 km2) to allow for a high fraction of cloudfree observations and to help to observing detailed spatial features. Daily measurements form a prerequisite for air quality data. This paper shows examples of OMI air quality measurements and it explains in what sense these measurements can be improved. This makes use of the results of a study in the Netherlands on air quality user requirements and instrument design for an OMI/SCIAMACHY follow-on instrument. The improvements are implemented in a new instrument, TROPOMI: an O2A channel is added to improve on surface and cloud albedo, cloud fraction and cloud top height and a new separate module is added for the SWIR wavelengths for measuring CO and CH4. The ground pixel is reduced to 10 × 10 km2 and signal-tonoises are improved to allow measurements in low albedo areas. The design makes use of newly developed detectors and new optics to reduce the overall instrument size. Lastly, the paper discusses the problem of data continuity for the coming 10-15 years, i.e. after AURA and ENVISAT end of life.