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Here we present water vapor vertical profiles observed with the ExoMars Trace Gas Orbiter/Nadir and Occultation for MArs Discovery instrument during the perihelion and Southern summer solstice season (LS = 240°–300°) in three consecutive Martian Years 34, 35, and 36. We show the detailed latitudinal distribution of H2O at tangent altitudes from 10 to 120 km, revealing a vertical plume at 60°S–50°S injecting H2O upward, reaching abundance of about 50 ppmv at 100 km. We have observed this event repeatedly in the three Martian years analyzed, appearing at LS = 260°–280° and showing inter‐annual variations in the magnitude and timing due to long term effects of the Martian Year 34 Global Dust Storm. We provide a rough estimate of projected hydrogen escape of 3.2 × 109 cm−2 s−1 associated to these plumes, adding further evidence of the key role played by the perihelion season in the long term evolution of the planet's climate. Plain Language Summary: Studying the vertical distribution of the Martian atmosphere is crucial to understand what happened to the water presumably present in larger abundance on ancient Mars. We have analyzed the vertical profiles of three Martian Years during the Southern summer, revealing a strong vertical transport of water vapor to the upper atmosphere. This seasonal phenomenon seems to be repeated annually, although with variations in the location and time of the year. Our estimation of the associated upward hydrogen flux represents an important loss which could have contributed to the escape of water to space for at least the period in which Mars had its present orbital inclination. Key Points: Latitudinal distributions of water vapor up to 120 km are analyzed in detail using Nadir and Occultation for MArs Discovery (NOMAD) observations with an improved retrieval schemeWater vapor injection during the perihelion localized around 50°–60°S in three consecutive Martian yearsMartian year 34 Global Dust Storm may have affected the driving mechanisms of the plume, delaying its appearance and reducing its magnitude [ABSTRACT FROM AUTHOR]

The water vapor in the Martian atmosphere plays a significant role in the planet's climate, being crucial in most of the chemical and radiative transfer processes. Despite its importance, the vertical distribution of H2O in the atmosphere has not still been characterized precisely enough. The recent ExoMars Trace Gas Orbiter mission, with its Nadir and Occultation for MArs Discovery instrument, has allowed us to measure the H2O vertical distribution with unprecedented resolution. Recent studies of vertical profiles have shown that high dust concentration in the atmosphere, in particular during dust storms, induces an efficient transport of the H2O to higher altitudes, from 40 km up to 80 km. We study the H2O vertical distribution in a subset of solar occultations during the perihelion of two Martian years (MYs), including the 2018 Global Dust Storm (GDS), in order to compare the same Martian season under GDS and non‐GDS conditions. We present our state‐of‐the‐art retrieval scheme, and we apply it to a combination of two diffraction orders, which permits sounding up to about 100 km. We confirm recent findings of H2O increasing at high altitudes during Ls = 190°–205° in MY 34, reaching abundances of about 150 ppmv at 80 km in both hemispheres not found during the same period of MY 35. We found a hygropause's steep rising during the GDS from 30 up to 80 km. Furthermore, strong supersaturation events have been identified at mesospheric altitudes even in presence of water ice layers retrieved by the IAA team. Plain Language Summary: The characterization of water vapor in the atmosphere is important for understanding the cycle of water on Mars and it is crucial in most of the atmospheric processes taking place in its current climate. The observation technique of the Nadir and Occultation for Mars Discovery onboard ExoMars Trace Gas Orbiter using solar occultations allows a high resolution vertical sampling of the atmosphere, permitting characterization of the H2O vertical distribution. In this work, we analyze the H2O distribution in the Martian atmosphere during the southern spring in Martian years 34 and 35. A Global Dust Storm event during the first one allowed us to study the atmospheric H2O and its response in the same season under intense and regular dusty conditions. We found that during intense dust storms, water vapor is present at higher altitudes rather than in regular atmospheric dust activity. This shows high concentrations of about 150 ppmv up to 80 km. As a consequence of the dust intensification, we observed an increase in the altitude of the 50 ppmv water vapor layer. Here, we report observations of atmospheric layers where H2O abundances exceed the theoretical needed saturation limit even when small particles are present. Key Points: Water vapor vertical distributions during the first half of the Martian perihelion season are presented from two consecutive Martian yearsStrong impact of the 2018 Global Dust Storm in the H2O abundances during MY 34, showing an increase on the hygropause's altitude compared to MY 35Atmospheric supersaturation events with presence of water ice at mesospheric altitudes are reported [ABSTRACT FROM AUTHOR]

In late September 2002, an Antarctic major stratospheric warming occurred, which led to a strong distortion of the southern polar vortex and to a split of its mid- and upper-stratospheric parts. Such an event had never before been observed since the beginning of regular Antarctic stratospheric temperature observations in the 1950s. The split is studied by means of nonoperational level-2 C[H.sub.4], [N.sub.2]O, CFC-11, and [O.sub.3] data, retrieved at the Institute for Meteorology and Climate Research Karlsruhe (IMK) from high-resolution atmospheric limb emission spectra from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the European research satellite, Environmental Satellite (ENVISAT). Retrieved horizontal and vertical distributions of C[H.sub.4] and [N.sub.2]O show good consistency with potential vorticity fields of the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis for the entire period under investigation, even for fine structures such as vortex filaments. Tracer correlation analysis suggests that mixing into the vortex had already occurred before the major warming and that vortex fragments were transported into the surrounding air masses on potential temperature levels above 400 K during the split. Correlation analysis of ozone with the source gases indicates slight ongoing ozone destruction in the lower-stratospheric vortex (below ~500 K) after the beginning of the warming event.

Profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European satellite Envisat have been retrieved from versions MIPAS/4.61 to MIPAS/4.62 and MIPAS/5.02 to MIPAS/5.06 level-1b data using the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK) and Consejo Superior de Investigaciones Científicas (CSIC), Instituto de Astrofísica de Andalucía (IAA). These profiles have been compared to measurements taken by the balloon-borne cryosampler, Mark IV (MkIV) and MIPAS-Balloon (MIPAS-B), the airborne MIPAS-STRatospheric aircraft (MIPAS-STR), the satellite-borne Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and the High Resolution Dynamic Limb Sounder (HIRDLS), as well as the ground-based Halocarbon and other Atmospheric Trace Species (HATS) network for the reduced spectral resolution period (RR: January 2005–April 2012) of MIPAS. ACE-FTS, MkIV and HATS also provide measurements during the high spectral resolution period (full resolution, FR: July 2002–March 2004) and were used to validate MIPAS CFC-11 and CFC-12 products during that time, as well as profiles from the Improved Limb Atmospheric Spectrometer, ILAS-II. In general, we find that MIPAS shows slightly higher values for CFC-11 at the lower end of the profiles (below  ∼  15 km) and in a comparison of HATS ground-based data and MIPAS measurements at 3 km below the tropopause. Differences range from approximately 10 to 50 pptv ( ∼  5–20 %) during the RR period. In general, differences are slightly smaller for the FR period. An indication of a slight high bias at the lower end of the profile exists for CFC-12 as well, but this bias is far less pronounced than for CFC-11 and is not as obvious in the relative differences between MIPAS and any of the comparison instruments. Differences at the lower end of the profile (below  ∼  15 km) and in the comparison of HATS and MIPAS measurements taken at 3 km below the tropopause mainly stay within 10–50 pptv (corresponding to  ∼  2–10 % for CFC-12) for the RR and the FR period. Between  ∼  15 and 30 km, most comparisons agree within 10–20 pptv (10–20 %), apart from ILAS-II, which shows large differences above  ∼  17 km. Overall, relative differences are usually smaller for CFC-12 than for CFC-11. For both species – CFC-11 and CFC-12 – we find that differences at the lower end of the profile tend to be larger at higher latitudes than in tropical and subtropical regions. In addition, MIPAS profiles have a maximum in their mixing ratio around the tropopause, which is most obvious in tropical mean profiles. Comparisons of the standard deviation in a quiescent atmosphere (polar summer) show that only the CFC-12 FR error budget can fully explain the observed variability, while for the other products (CFC-11 FR and RR and CFC-12 RR) only two-thirds to three-quarters can be explained. Investigations regarding the temporal stability show very small negative drifts in MIPAS CFC-11 measurements. These instrument drifts vary between  ∼  1 and 3 % decade−1. For CFC-12, the drifts are also negative and close to zero up to  ∼  30 km. Above that altitude, larger drifts of up to  ∼  50 % decade−1 appear which are negative up to  ∼  35 km and positive, but of a similar magnitude, above. [ABSTRACT FROM AUTHOR]

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is an infrared (IR) limb emission spectrometer on the Envisat platform. It measures trace gas distributions during day and night, pole-to-pole, over an altitude range from 6 to 70 km in nominal mode and up to 170 km in special modes, depending on the measurement mode, producing more than 1000 profiles day-1. We present the results of a validation study of methane, version V5R_CH4_222, retrieved with the IMK/IAA (Institut für Meteorologie und Klimaforschung, Karlsruhe/Instituto de Astrofisica de Andalucia, Grenada) MIPAS scientific level 2 processor. The level 1 spectra are provided by the ESA (European Space Agency) and version 5 was used. The time period covered is 2005-2012, which corresponds to the period when MIPAS measured trace gas distributions at a reduced spectral resolution of 0.0625 cm-1. The comparison with satellite instruments includes the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS), the HALogen Occultation Experiment (HALOE), the Solar Occultation For Ice Experiment (SOFIE) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHar-tographY (SCIAMACHY). Furthermore, comparisons with MkIV balloon-borne solar occultation measurements and with air sampling measurements performed by the University of Frankfurt are presented. The validation activities include bias determination, assessment of stability, precision validation, analysis of histograms and comparison of corresponding climatologies. Above 50 km altitude, MIPAS methane mixing ratios agree within 3 % with ACE-FTS and SOFIE. Between 30 and 40 km an agreement within 3 % with SCIAMACHY has been found. In the middle stratosphere, there is no clear indication of a MIPAS bias since comparisons with various instruments contradict each other. In the lower stratosphere (below 25 km) MIPAS CH4 is biased high with respect to satellite instruments, and the most likely estimate of this bias is 14 %. However, in the comparison with CH4 data obtained from cryogenic whole-air sampler (cryosam-pler) measurements, there is no evidence of a high bias in MIPAS between 20 and 25 km altitude. Precision validation is performed on collocated MIPAS-MIPAS pairs and suggests a slight underestimation of its uncertainties by a factor of 1.2. No significant evidence of an instrumental drift has been found. [ABSTRACT FROM AUTHOR]

A new and improved setup of the SF6 retrieval together with a newly calibrated version of MIPAS-ENVISAT level 1b spectra (version 5, ESA data version 5.02/5.06) was used to obtain a new global SF6 data set, covering the total observational period of MIPAS from July 2002 to April 2012 for the first time. Monthly and zonally averaged SF6 profiles were converted into mean age of air using a tropospheric SF6-reference curve. The obtained data set of age of air was compared to airborne age of air measurements. The temporal evolution of the mean age of air was then investigated in 10 latitude and 1-2 km altitude bins. A regression model consisting of a constant and a linear trend term, two proxies for the quasi-biennial oscillation variation, sinusoidal terms for the seasonal and semiannual variation and overtones was fitted to the age of air time series. The annual cycle for particular regions in the stratosphere was investigated and compared to other studies. The age of air trend over the total MIPAS period consisting of the linear term was assessed and compared to previous findings of Stiller et al. (2012). While the linear increase of mean age is confirmed to be positive for the northern midlatitudes and southern polar middle stratosphere, differences are found in the northern polar upper stratosphere, where the mean age is now found to increase as well. The magnitude of trends in the northern midlatitude middle stratosphere is slightly lower compared to the previous version and the trends fit remarkably well to the trend derived by Engel et al. (2009). Negative age of air trends found by Stiller et al. (2012) are confirmed for the lowermost tropical stratosphere and lowermost southern midlatitudinal stratosphere. Differences to the previous data versions occur in the middle tropical stratosphere around 25 km, where the trends are now negative. Overall, the new latitude-altitude distribution of trends appears to be less patchy and more coherent than the previous one. The new data provide evidence of an accelerating shallow branch of the Brewer-Dobson circulation, at least in the Southern Hemisphere. Finally the age of air decadal trends are compared to trends calculated with simulated SF6 values by the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA) and good agreement is found. The hemispheric asymmetry in the trends found in the MIPAS data is also indicated in the trends calculated with simulated SF6 values by the KASIMA model. [ABSTRACT FROM AUTHOR]

We present the strongly revised IMK/IAA MIPAS-ENVISAT CH4 and N2O data products for the MIPAS full-resolution (versions V5H_CH4_21 and V5H_N2O_21) and for the reduced-resolution period (versions V5R_CH4_224, V5R_CH4_225, V5R_N2O_224 and V5R_N2O_225). These data sets cover both MIPAS measurement periods from June 2002 until March 2004 and from January 2005 to April 2012. Differences with older retrieval versions which are known to have a high bias are discussed. The usage of the HITRAN 2008 spectroscopic data set leads to lower values for both gases in the lower part of the profile. The improved correction of additive radiance offsets and handling of background radiance continua allows for aerosol contributions at altitudes in the upper stratosphere and above. These changes lead to more plausible values, both in the radiance offset and in the profiles of the continuum absorption coefficients. They also increase the fraction of converged retrievals. Some minor changes were applied to the constraint of the inverse problem, causing small differences in the retrieved profiles, mostly due to the relaxation of off-diagonal regularisation matrix elements for the calculation of jointly retrieved absorption coefficient profiles. Spectral microwindows have been adjusted to avoid areas with saturated spectral signatures. Jointly retrieving profiles of water vapour and nitric acid serves to compensate spectroscopic inconsistencies. We discuss the averaging kernels of the profiles and their vertical resolution. The latter ranges from 2.5 to 7 km for CH4, and from 2.5 to 6 km for N2O in the reducedresolution period. For the full-resolution period, the vertical resolution is in the order of 3 to 6 km for both gases. We find the retrieval errors in the lower part of the profiles mostly to be around 15% for CH4 and below 10% for N2O. The errors above 25 or 30 km increase to values between 10 and 20 %, except for CH4 from the reduced-resolution period, where the estimated errors stay below 15 %. [ABSTRACT FROM AUTHOR]

Vertically resolved distributions of sulfur dioxide (SO2) with global coverage in the height region from the upper troposphere to ~20 km altitude have been derived from observations by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat for the period July 2002 to April 2012. Retrieved volume mixing ratio profiles representing single measurements are characterized by typical errors in the range of 70-100 pptv and by a vertical resolution ranging from 3 to 5 km. Comparison with observations by the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) revealed a slightly varying bias with altitude of -20 to 50 pptv for the MIPAS data set in case of volcanically enhanced concentrations. For background concentrations the comparison showed a systematic difference between the two major MIPAS observation periods. After debiasing, the difference could be reduced to biases within -10 to 20 pptv in the altitude range of 10-20 km with respect to ACE-FTS. Further comparisons of the debiased MIPAS data set with in situ measurements from various aircraft campaigns showed no obvious inconsistencies within a range of around ±50 pptv. The SO2 emissions of more than 30 volcanic eruptions could be identified in the upper troposphere and lower stratosphere (UTLS). Emitted SO2 masses and lifetimes within different altitude ranges in the UTLS have been derived for a large part of these eruptions. Masses are in most cases within estimations derived from other instruments. From three of the major eruptions within the MIPAS measurement period - Kasatochi in August 2008, Sarychev in June 2009 and Nabro in June 2011 - derived lifetimes of SO2 for the altitude ranges 10-14, 14-18 and 18-22 km are 13.3 ± 2.1, 23.6 ± 1.2 and 32.3 ± 5.5 days respectively. By omitting periods with obvious volcanic influence we have derived background mixing ratio distributions of SO2. At 10 km altitude these indicate an annual cycle at northern mid- and high latitudes with maximum values in summer and an amplitude of about 30 pptv. At higher altitudes of about 16-18 km, enhanced mixing ratios of SO2 can be found in the regions of the Asian and the North American monsoons in summer - a possible connection to an aerosol layer discovered by Vernier et al. (2011b) in that region. [ABSTRACT FROM AUTHOR]

We present a HCN climatology of the years 2002-2012, derived from FTIR limb emission spectra measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the ENVISAT satellite, with the main focus on biomass burning signatures in the upper troposphere and lower stratosphere. HCN is an almost unambiguous tracer of biomass burning with a tropospheric lifetime of 5-6 months and a stratospheric lifetime of about 2 years. The MIPAS climatology is in good agreement with the HCN distribution obtained by the spaceborne ACE-FTS experiment and with airborne in situ measurements performed during the INTEX-B campaign. The HCN amounts observed by MIPAS in the southern tropical and subtropical upper troposphere have an annual cycle peaking in October-November, i.e. 1-2 months after the maximum of southern hemispheric fire emissions. The probable reason for the time shift is the delayed onset of deep convection towards austral summer. Because of overlap of varying biomass burning emissions from South America and southern Africa with sporadically strong contributions from Indonesia, the size and strength of the southern hemispheric plume have considerable interannual variations, with monthly mean maxima at, for example, 14 km between 400 and more than 700pptv. Within 1-2 months after appearance of the plume, a considerable portion of the enhanced HCN is transported southward to as far as Antarctic latitudes. The fundamental period of HCN variability in the northern upper troposphere is also an annual cycle with varying amplitude, which in the tropics peaks in May after and during the biomass burning seasons in northern tropical Africa and southern Asia, and in the subtropics peaks in July due to trapping of pollutants in the Asian monsoon anticyclone (AMA). However, caused by extensive biomass burning in Indonesia and by northward transport of part of the southern hemispheric plume, northern HCN maxima also occur around October/November in several years, which leads to semi-annual cycles. There is also a temporal shift between enhanced HCN in northern low and mid- to high latitudes, indicating northward transport of pollutants. Due to additional biomass burning at mid- and high latitudes, this meridional transport pattern is not as clear as in the Southern Hemisphere. Upper tropospheric HCN volume mixing ratios (VMRs) above the tropical oceans decrease to below 200 pptv, presumably caused by ocean uptake, especially during boreal winter and spring. The tropical stratospheric tape recorder signal with an apparently biennial period, which was detected in MLS and ACE-FTS data from mid-2004 to mid-2007, is corroborated by MIPAS HCN data. The tape recorder signal in the whole MIPAS data set exhibits periodicities of 2 and 4 years, which are generated by interannual variations in biomass burning. The positive anomalies of the years 2003, 2007 and 2011 are caused by succession of strongly enhanced HCN from southern hemispheric and Indonesian biomass burning in boreal autumn and of elevated HCN from northern tropical Africa and the AMA in subsequent spring and summer. The anomaly of 2005 seems to be due to springtime emissions from tropical Africa followed by release from the summertime AMA. The vertical transport time of the anomalies is 1 month or less between 14 and 17 km in the upper troposphere and 8-11 months between 17 and 25 km in the lower stratosphere. [ABSTRACT FROM AUTHOR]

We present a climatology of monthly and 10 zonal mean profiles of sulfur dioxide (SO2) volume mixing ratios (vmr) derived from MIPAS/Envisat measurements in the altitude range 15-45 km from July 2002 until April 2012. The vertical resolution varies from 3.5-4 km in the lower stratosphere up to 6-10 km at the upper end of the profiles, with estimated total errors of 5-20 pptv for single profiles of SO2. Comparisons with the few available observations ofSO2 up to high altitudes from ATMOS for a volcanically perturbed situation from ACE-FTS and, at the lowest altitudes, with stratospheric in situ observations reveal general consistency of the datasets. The observations are the first empirical confirmation of features of the stratosphericSO2 distribution, which have only been shown by models up to now: (1) the local maximum ofSO2 at around 25-30 km altitude, which is explained by the conversion of carbonyl sulfide (COS) as the precursor of the Junge layer; and (2) the downwelling ofSO2-rich air to altitudes of 25-30 km at high latitudes during winter and its subsequent depletion on availability of sunlight. This has been proposed as the reason for the sudden appearance of enhanced concentrations of condensation nuclei during Arctic and Antarctic spring. Further, the strong increase ofSO2 to values of 80-100 pptv in the upper stratosphere through photolysis of H2SO4 has been confirmed. Lower stratospheric variability ofSO2 could mainly be explained by volcanic activity, and no hints of a strong anthropogenic influence have been found. Regression analysis revealed a QBO (quasi-biennial oscillation) signal of the SO2 time series in the tropics at about 30-35 km, an SAO (semi-annual oscillation) signal at tropical and subtropical latitudes above 32 km and annual periodics predominantly at high latitudes. Further, the analysis indicates a correlation with the solar cycle in the tropics and southern subtropics above 30 km. Significant negative linear trends are found in the tropical lower stratosphere, probably due to reduced tropical volcanic activity and at southern mid-latitudes above 35 km. A positive trend is visible in the lower and middle stratosphere at polar to subtropical southern latitudes. [ABSTRACT FROM AUTHOR]

Vertical profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) have been measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) with global coverage under daytime and nighttime conditions. The profile retrieval is based on constrained nonlinear least squares fitting of measured limb spectral radiance to modeled spectra. CFC-11 is measured in its v4-band at 850 cm-1, and CFC-12 is analyzed in its v6-band at 922 cm-1. To stabilize the retrievals, a Tikhonov-type smoothing constraint is applied. Main retrieval error sources are measurement noise and elevation pointing uncertainties. The estimated CFC-11 retrieval errors including noise and parameter errors but excluding spectroscopic data uncertainties are below 10 pptv in the middle stratosphere, depending on altitude, the MI-PAS measurement mode and the actual atmospheric situation. For CFC-12 the total retrieval errors are below 28 pptv at an altitude resolution varying from 3 to 5 km. Time series of altitude/latitude bins were fitted by a simple parametric approach including constant and linear terms, a quasi-biennial oscillation (QBO) proxy and sine and cosine terms of several periods. In the time series from 2002 to 2011, quasi-biennial and annual oscillations are clearly visible. A decrease of stratospheric CFC mixing ratios in response to the Montreal Protocol is observed for most altitudes and latitudes. However, the trends differ from the trends measured in the troposphere, they are even positive at some latitudes and altitudes, and can in some cases only be explained by decadal changes in atmospheric age of air spectra or vertical mixing patterns. [ABSTRACT FROM AUTHOR]

The kinetic temperature and line of sight elevation information are retrieved from the MIPAS Middle Atmosphere (MA), Upper Atmosphere (UA) and NoctiLucent-Cloud (NLC) modes of high spectral resolution limb observations of the CO2 15 µm emission using the dedicated IMK/IAA retrieval algorithm, which considers non-local thermodynamic equilibrium conditions. These variables are accurately derived from about 20 km (MA) and 40 km (UA and NLC) to 105 km globally and both at daytime and nighttime. Typical temperature random errors are smaller than 0.5K below 50 km, 0.5-2K at 50-70 km, and 2-7K above. The systematic error is typically 1K below 70 km, 1-3K from 70 to 85 km and 3-11K from 85 to 100 km. The average vertical resolution is typically 4 km below 35 km, 3 km at 35-50 km, 4-6 km at 50-90 km, and 6-10 km above. We compared our MIPAS temperature retrievals from 2005 to 2009 with co-located ground-based measurements from the lidars located at the Table Mountain Facility and Mauna Loa Observatory, the SATI spectrograph in Granada (Spain) and the Davis station spectrometer, and satellite observations from ACE-FTS, Aura-MLS and TIMED-SABER from 20 km to 100 km. We also compared MIPAS temperatures with the high latitudes climatology from falling sphere measurements. The comparisons show very good agreement, with differences smaller than 3K below 85-90 km in midlatitudes. Differences over the poles in this altitude range are larger but can be generally explained in terms of known biases of the other instruments. The comparisons above 90 km worsen and MIPAS retrieved temperatures are always larger than other instrument measurements. [ABSTRACT FROM AUTHOR]

MIPAS-ENVISAT full resolution spectra were analyzed to obtain a global distribution of hydrogen peroxide (H2O2) in the stratosphere. H2O2 acts as reservoir gas for the HOx family (=H+OH+HO2) and thus, observations of H2O2 provide a better understanding of the HOx chemistry in the atmosphere. A retrieval approach based on constrained least squares fitting was developed and applied to small dedicated spectral analysis windows with maximum H2O2 information and minimum contribution of interfering gases. Due to a low signal to noise ratio in the measured spectra single profiles cannot be used for scientific interpretation and about 100 profiles have to be averaged temporally or spatially. Our retrievals of H2O2 from MIPAS measurements provide meaningful results between approximately 20 and 60 km. A possible impact by the high uncertainty of the reaction rate constant for HO2 +HO2→H2O2 +O2 in our 3D-CTMKASIMA is discussed. We find best agreement between model and observations for applying rate constants according to Christensen et al. (2002), however, a mismatch in vertical profile shape remains. The observations were compared to themodel results of KASIMA focusing on low to mid latitudes. Good agreement in spatial distribution and in temporal evolution was found. Highest vmr of H2O2 in the stratosphere were observed and modeled in low latitudes shortly after equinox at about 30 km. The modelled diurnal cycle with lowest vmr shortly after sunrise and highest vmr in the afternoon is confirmed by the MIPAS observations. [ABSTRACT FROM AUTHOR]

The article presents a study on the distributions of several air pollutants retrieved from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) reduced spectral resolution nominal mode limb emission measurements. It discusses how the study was conducted which involved IMK-IAA research processor. The study reportedly revealed that the largest mixing ratios are found in the troposhere.

An extensive observational data set, consisting of more than 106 SF6 vertical profiles from MIPAS measurements distributed over the whole globe has been condensed into monthly zonal means of mean age of air for the period September 2002 to January 2010, binned at 10° latitude and 1-2 km altitude. The data were analysed with respect to their temporal variation by fitting a regression model consisting of a constant and a linear increase term, 2 proxies for the QBO variation, sinusoidal terms for the seasonal and semi-annual variation and overtones for the correction of the shapes to the observed data set. The impact of subsidence of mesospheric SF6-depleted air and in-mixing into non-polar latitudes on mid-latitudinal absolute age of air and its linear increase was assessed and found to be small. The linear increase of mean age of stratospheric air was found to be positive and partly larger than the trend derived by Engel et al. (2009) for most of the Northern mid-latitudes, the middle stratosphere in the tropics, and parts of the Southern mid-latitudes, as well as for the Southern polar upper stratosphere. Multi-year decrease of age of air was found for the lowermost and the upper stratospheric tropics, for parts of Southern mid-latitudes, and for the Northern polar regions. Analysis of the amplitudes and phases of the seasonal variation shed light on the coupling of stratospheric regions to each other. In particular, the Northern mid-latitude stratosphere is well coupled to the tropics, while the Northern lowermost mid-latitudinal stratosphere is decoupled, confirming the separation of the shallow branch of the Brewer-Dobson circulation from the deep branch. We suggest an overall increased tropical upwelling, together with weakening of mixing barriers, especially in the Northern Hemisphere, as a hypothetical model to explain the observed pattern of linear multi-year increase/decrease, and amplitudes and phase shifts of the seasonal variation. [ABSTRACT FROM AUTHOR]

MIPAS-ENVISAT full resolution spectra were analyzed to obtain a global distribution of hydrogen peroxide (H2O2) in the stratosphere. H2O2 acts as reservoir gas for the HOx family (=H+OH+HO2) and thus, observations of H2O2 provide a better understanding of the HOx chemistry in the atmosphere. A retrieval approach based on constrained least squares fitting was developed and applied to small dedicated spectral analysis windows with maximum H2O2 information and minimum contribution of interfering gases. Due to a low signal to noise ratio in the measured spectra single profiles cannot be used for scientific interpretation and about 100 profiles have to be averaged temporally or spatially. Our retrievals of H2O2 from MIPAS measurements provide meaningful results between approximately 20 and 60 km. A possible impact by the high uncertainty of the reaction rate constant for HO2 + HO2→H2O2 + O2 in our 3d-CTM KASIMA is discussed. We find best agreement between model and observations for applying rate constants according to Christensen et al. (2002). The observations were compared to the model results of KASIMA focusing on low to mid latitudes. Good agreement in spatial distribution and in temporal evolution was found. Highest vmr of H2O2 in the stratosphere were observed and modeled in low latitudes shortly after equinox at about 30 km. The modelled diurnal cycle with lowest vmr shortly after sunrise and highest vmr in the afternoon is confirmed by the MIPAS observations. [ABSTRACT FROM AUTHOR]

An extensive observational data set, consisting of more than 106 SF6 vertical profiles distributed globally from MIPAS measurements has been condensed into monthly zonal means of mean age of air for the period September 2002 to January 2010, binned at 10° latitude and 1-2 km altitude. The data were analysed with respect to their temporal variation by fitting a regression model consisting of a constant and a linear increase term, 2 proxies for the QBO variation, sinusoidal terms for the seasonal and semi-annual variation and overtones for the correction of the shapes to the observed data set. The impact of subsidence of mesospheric SF6-depleted air and in-mixing into non-polar latitudes on mid-latitudinal absolute age of air and its linear increase was assessed and found to be small. The linear increase of mean age of stratospheric air was found to be positive and partly larger than the trend derived by Engel et al. (2009) for most of the Northern mid-latitudes, the middle stratosphere in the tropics, and parts of the Southern mid-latitudes, as well as for the Southern polar upper stratosphere. Multi-year decrease of age of air was found for the lowermost and the upper stratospheric tropics, for parts of Southern mid-latitudes, and for the Northern polar regions. Analysis of the amplitudes and phases of the seasonal variation shed light on the coupling of stratospheric regions to each other. In particular, the Northern mid-latitude stratosphere is well coupled to the tropics, while the Northern lowermost mid-latitudinal stratosphere is decoupled, confirming the separation of the shallow branch of the Brewer-Dobson circulation from the deep branch. We suggest an overall increased tropical upwelling, together with weakening of mixing barriers, especially in the Northern Hemisphere, as a hypothetical model to explain the observed pattern of linear multi-year increase/decrease, and amplitudes and phase shifts of the seasonal variation. [ABSTRACT FROM AUTHOR]

The article presents a study which compares measurements by Odin/SMR and SCISAT/ACE-FTS in order to measure the quality of the HDO data set. It reveals that measurements of thermal emission in the mid-infrared by Envisat/MIPAS allow the retrieval of HDO data in the altitude range between 10 kilometers and 50 kilometers. Comparisons were conducted on profile-to-profile basis using seasonal and monthly averages.

The kinetic temperature and line of sight elevation information are retrieved from the MIPAS Middle Atmosphere (MA), Upper Atmosphere (UA) and NoctiLucent-Cloud (NLC) modes of high spectral resolution limb observations of the CO2 15 µm emission using the dedicated IMK/IAA retrieval algorithm, which considers non-local thermo-dynamic equilibrium conditions. These variables are accurately derived from about 20 km (MA) and 40 km (UA and NLC) to 105 km globally and both at daytime and nighttime. Typical temperature random errors are smaller than 0.5 K below 50 km, 0.5-2K at 50-70 km, and 2-8K above. The systematic error is typically 1 K below 70 km, 1- 3 K from 70 to 85km and 3-11K from 85 to 100 km. The average vertical resolution is typically 4 km below 35 km, 3km at 35-50 km, 4-6 km at 50-90 km, and 6-10km above. We compared our MIPAS temperature retrievals from 2005 to 2009 with co-located ground-based measurements from the lidars located at the Table Mountain Facility and Mauna Loa Observatory, the SATI spectrograph in Granada (Spain) and the Davis station spectrometer, and satellite observations from ACE-FTS, Aura-MLS and TIMED-SABER from 20 km to 100 km. We also compared MIPAS temperatures with the high latitudes climatology from falling sphere measurements. The comparisons show very good agreement, with differences smaller than 3K below 85-90 km in mid-latitudes. Differences over the poles in this altitude range are larger but can be generally explained in terms of known biases of the other instruments. The comparisons above 90 km worsen and MIPAS retrieved temperatures are always larger than other instrument measurements. [ABSTRACT FROM AUTHOR]

The article presents a study which shows reduced spectral resolution (RR) retrievals of ethane (C2H6), ethine (C2H2), hydrogen cyanide (HCN), and peroxyacetyl nitrate (PAN). The study analyzed C2H6, C2H2, HCN, and PAN from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) reduced spectral resolution measurements. It reveals that the largest mixing ratios are found in the troposphere.

Estimation of a trend of an atmospheric state variable is usually performed by fitting a linear regression line to a set of data of this variable sampled at different times. Often these data are irregularly sampled in space and time and clustered in a sense that error correlations among data points cause a similar error of data points sampled at similar times. Since this can affect the estimated trend, we suggest to take the full error covariance matrix of the data into account. Superimposed periodic variations can be jointly fitted in a straightforward manner, even if the shape of the periodic function is not known. Global data sets, particularly satellite data, can form the basis to estimate the error correlations. State-dependent amplitudes of superimposed periodic corrections result in a non-linear optimization problem which is solved iteratively. [ABSTRACT FROM AUTHOR]