scholarly journals Validation of revised methane and nitrous oxide profiles from MIPAS–ENVISAT

2016 ◽  
Vol 9 (2) ◽  
pp. 765-779 ◽  
Author(s):  
Johannes Plieninger ◽  
Alexandra Laeng ◽  
Stefan Lossow ◽  
Thomas von Clarmann ◽  
Gabriele P. Stiller ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
Species Group ◽  
Mixing Ratios ◽  
Full Resolution ◽  
Trace Species ◽  
Surface Data ◽  
Ch4 And N2o ◽  
Scanning Imaging ◽  
The Fourier Transform

Abstract. Improved versions of CH4 and N2O profiles derived at the Institute of Meteorology and Climate Research and Instituto de Astrofísica de Andalucía (CSIC) from spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) have become available. For the MIPAS full-resolution period (2002–2004) these are V5H_CH4_21 and V5H_N2O_21 and for the reduced-resolution period (2005–2012) these are V5R_CH4_224, V5R_CH4_225, V5R_N2O_224 and V5R_N2O_225. Here, we compare CH4 profiles to those measured by the Fourier Transform Spectrometer on board of the Atmospheric Chemistry Experiment (ACE-FTS), the HALogen Occultation Experiment (HALOE) and the Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY), to the Global Cooperative Air Sampling Network (GCASN) surface data. We find the MIPAS CH4 profiles below 25 km to be typically higher of the order of 0.1 ppmv for both measurement periods. N2O profiles are compared to those measured by ACE-FTS, the Microwave Limb Sounder on board of the Aura satellite (Aura-MLS) and the Sub-millimetre Radiometer on board of the Odin satellite (Odin-SMR) as well as to the Halocarbons and other Atmospheric Trace Species Group (HATS) surface data. The mixing ratios of the satellite instruments agree well with each other for the full-resolution period. For the reduced-resolution period, MIPAS produces similar values as Odin-SMR, but higher values than ACE-FTS and HATS. Below 27 km, the MIPAS profiles show higher mixing ratios than Aura-MLS, and lower values between 27 and 41 km. Cross-comparisons between the two MIPAS measurement periods show that they generally agree quite well, but, especially for CH4, the reduced-resolution period seems to produce slightly higher mixing ratios than the full-resolution data.

scholarly journals Validation of revised methane and nitrous oxide profiles from MIPAS-ENVISAT

2015 ◽  
Vol 8 (11) ◽  
pp. 12105-12153
Author(s):  
J. Plieninger ◽  
A. Laeng ◽  
S. Lossow ◽  
T. von Clarmann ◽  
G. P. Stiller ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
Species Group ◽  
Mixing Ratios ◽  
Full Resolution ◽  
Trace Species ◽  
Surface Data ◽  
Ch4 And N2o ◽  
Scanning Imaging ◽  
The Fourier Transform

Abstract. Improved versions of CH4 and N2O profiles derived at the Institute of Meteorology and Climate Research and Instituto de Astrofísica de Andalucía (CSIC) from spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) have become available. For the MIPAS full resolution period (2002–2004) these are V5H_CH4_21 and V5H_N2O_21 and for the reduced resolution period (2005–2012) these are V5R_CH4_224, V5R_CH4_225, V5R_N2O_224 and V5R_N2O_225. Here, we compare CH4 profiles to those measured by the Fourier Transform Spectrometer on board of the Atmospheric Chemistry Experiment (ACE-FTS), the HALogen Occultation Experiment (HALOE) and the Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) and to the Global Cooperative Air Sampling Network (GCASN) surface data. We find the MIPAS CH4 profiles below 25 km to be typically higher in the order of 0.1 ppmv for both measurement periods. N2O profiles are compared to those measured by ACE-FTS, the Microwave Limb Sounder on board of the Aura satellite (Aura-MLS) and the Sub-millimetre Radiometer on board of the Odin satellite (Odin-SMR) as well as to the Halocarbons and other Atmospheric Trace Species Group (HATS) surface data. The mixing ratios from the satellite instruments agree well for the full resolution period. For the reduced resolution period, MIPAS produces similar values as Odin-SMR, but higher values than ACE-FTS and HATS. Below 27 km, the MIPAS profiles show higher mixing ratios than Aura-MLS, and lower values between 27 and 41 km. Cross comparisons between the two MIPAS measurement periods show that they generally agree quite well, but, especially for CH4, the reduced resolution period seems to produce slightly higher mixing ratios than the full resolution data.

scholarly journals Validation of MIPAS IMK/IAA methane profiles

2015 ◽  
Vol 8 (12) ◽  
pp. 5251-5261 ◽  
Author(s):  
A. Laeng ◽  
J. Plieninger ◽  
T. von Clarmann ◽  
U. Grabowski ◽  
G. Stiller ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
European Space Agency ◽  
Trace Gas ◽  
Mixing Ratios ◽  
Air Sampler ◽  
Solar Occultation ◽  
Space Agency ◽  
Scanning Imaging ◽  
Satellite Instruments

Abstract. 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 CHartographY (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 (cryosampler) 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.

scholarly journals Validation of MIPAS IMK/IAA methane profiles

2015 ◽  
Vol 8 (6) ◽  
pp. 5565-5590 ◽  
Author(s):  
A. Laeng ◽  
J. Plieninger ◽  
T. von Clarmann ◽  
U. Grabowski ◽  
G. Stiller ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
Mixing Ratios ◽  
Solar Occultation ◽  
Time Period ◽  
Measurement Mode ◽  
High Bias ◽  
Scanning Imaging ◽  
The University ◽  
Satellite Instruments

Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was an infra-red (IR) limb emission spectrometer on the Envisat platform. It measured 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 MIPAS scientific level 2 processor. The level 1 spectra are provided by ESA, the version 5 was used. The time period covered corresponds to the period when MIPAS measured at reduced spectral resolution, i.e. 2005–2012. 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 CHartographY (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, in selected cases, assessment 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 about 25–30 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 cryosampler measurements, there is no evidence of a MIPAS high bias between 20 and 25 km altitude. Precision validation is performed on collocated MIPAS-MIPAS pairs and suggests a slight underestimation of its errors by a factor of 1.2. A parametric model consisting of constant, linear, QBO and several sine and cosine terms with different periods has been fitted to the temporal variation of differences of stratospheric CH4 measurements by MIPAS and ACE-FTS for all 10° latitude/1–2 km altitude bins. Only few significant drifts can be calculated, due to the lack of data. Significant drifts with respect to ACE-FTS tend to have higher absolute values in the Northern Hemisphere, have no pronounced tendency in the sign, and do not exceed 0.2 ppmv per decade in absolute value.

scholarly journals MIPAS IMK/IAA CFC-11 (CCl<sub>3</sub>F) and CFC-12 (CCl<sub>2</sub>F<sub>2</sub>) measurements: accuracy, precision and long-term stability

2016 ◽  
Vol 9 (7) ◽  
pp. 3355-3389 ◽  
Author(s):  
E. Eckert ◽  
A. Laeng ◽  
S. Lossow ◽  
S. Kellmann ◽  
G. Stiller ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
Temporal Stability ◽  
High Spectral Resolution ◽  
Long Term Stability ◽  
Full Resolution ◽  
Trace Species ◽  
Institute Of Technology ◽  
Relative Differences

Abstract. 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.

scholarly journals Impact of temperature field inhomogeneities on the retrieval of atmospheric species from MIPAS IR limb emission spectra

2010 ◽  
Vol 3 (5) ◽  
pp. 1487-1507 ◽  
Author(s):  
M. Kiefer ◽  
E. Arnone ◽  
A. Dudhia ◽  
M. Carlotti ◽  
E. Castelli ◽  
...  
Keyword(s):  
Temperature Field ◽  
Temperature Gradient ◽  
Michelson Interferometer ◽  
Emission Spectra ◽  
Monthly Means ◽  
Atmospheric Species ◽  
Mixing Ratios ◽  
Observation Strategy ◽  
Ch4 And N2o ◽  
Relative Differences

Abstract. We examine volume mixing ratios (vmr) retrieved from limb emission spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board Envisat. In level 2 (L2) data products of three different retrieval processors, which perform one dimensional (1-D) retrievals, we find significant differences between species' profiles from ascending and descending orbit parts. The relative differences vary systematically with time of the year, latitude, and altitude. In the lower stratosphere their monthly means can reach maxima of 20% for CFC-11, CFC-12, HNO3, H2O, 10% for CH4 and N2O. Relative differences between monthly means of 1-D retrieval results and of the true atmospheric state can be expected to reach half of these percentage values, while relative differences in single vmr profiles might well exceed those numbers. Often there are no physical or chemical reasons for these differences, so they are an indicator for a problem in the data processing. The differences are generally largest at locations where the meridional temperature gradient of the atmosphere is strong. On the contrary, when performing the retrieval with a tomographic two dimensional (2-D) retrieval, L2 products generally do not show these differences. This suggests that inhomogeneities in the temperature field, and possibly in the species' fields, which are accounted for in the 2-D algorithm and not in standard 1-D processors, may cause significant deviations in the results. Inclusion of an externally given adequate temperature gradient in the forward model of a 1-D processor helps to reduce the observed differences. However, only the full tomographic 2-D approach is suitable to resolve the horizontal inhomogeneities. Implications for the use of the 1-D data, e.g. for validation, are discussed. The dependence of the ascending/descending differences on the observation strategy suggests that this problem may affect 1-D retrievals of infrared limb sounders, if the line of sight of the instrument has a significant component in the direction of the horizontal temperature variation.

Study on Stratospheric Carbonyl Sulfide Transport and Chemistry using ‘Age of Air’

2021 ◽  
Author(s):  
Chenxi Qiu ◽  
Felix Ploeger ◽  
Jens-Uwe Grooß ◽  
Marc von Hobe
Keyword(s):  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
Carbonyl Sulfide ◽  
Polar Vortex ◽  
Lagrangian Model ◽  
Latitude Range ◽  
Mixing Ratios ◽  
Enhanced Absorption ◽  
In Situ Data

&lt;p&gt;Carbonyl sulfide (OCS or COS) is the longest lived and the most abundant reduced sulfur gas in the atmosphere. As chemical loss of OCS in the troposphere is slow, it can reach the stratosphere, where it is &amp;#160;photochemically oxidized and converted to stratospheric sulfate aerosol, being the largest source thereof in times of volcanic quiescence. Chemistry transport models show that OCS conversion occurs mainly in the &amp;#8216;tropical pipe&amp;#8217; region, while along the lower branch of Brewer-Dobson circulation (BDC), OCS is passively transported without significant chemical loss. The OCS depleted air is transported along the upper branch of BDC and descends again at high latitudes. Using the distinct characteristics of &amp;#160;&amp;#8216;age of air&amp;#8217; in the upper and lower branches of the BDC, this picture of OCS transport and especially the role of the &amp;#8216;tropical pipe&amp;#8217; as the main region of OCS conversion can be supported by looking at the relationship between age spectra and OCS mixing ratios.&lt;/p&gt;&lt;p&gt;In this study, we will investigate the relation of OCS mixing ratios and mean age of air as well as mass fractions of air with different transit times using satellite-based measurements from MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) and ACE-FTS (Atmospheric Chemistry Experiment - infrared Fourier Transform Spectrometer), and age spectra of air from CLaMS (Chemical Lagrangian Model of the Stratosphere).&lt;/p&gt;&lt;p&gt;In addition to satellite data analysis, we will investigate the distribution of OCS in the UTLS (upper troposphere and lower stratosphere) region and its relation to the age spectra using high-resolution in-situ observations of OCS. This unique dataset was obtained during the SOUTHTRAC mission in autumn 2019 by AMICA (Airborne Mid-Infrared Cavity enhanced Absorption spectrometer) on board the HALO (High Altitude Long Range) research aircraft. Flights from the main &amp;#160;campaign base in R&amp;#237;o Grande, Argentina (53.8S, 67.7W) covered a wide latitude range from 48&amp;#176; N to 70&amp;#176; S, even reaching the southern polar vortex where aged air masses having descended from high altitudes are typically found.&lt;/p&gt;&lt;p&gt;Our analysis of both satellite and in-situ data generally supports the established picture of OCS conversion in the &amp;#8216;tropical pipe&amp;#8217;.&lt;/p&gt;

scholarly journals CFC-11, CFC-12 and HCFC-22 ground-based remote sensing FTIR measurements at Réunion Island and comparisons with MIPAS/ENVISAT data

2016 ◽  
Vol 9 (11) ◽  
pp. 5621-5636 ◽  
Author(s):  
Minqiang Zhou ◽  
Corinne Vigouroux ◽  
Bavo Langerock ◽  
Pucai Wang ◽  
Geoff Dutton ◽  
...  
Keyword(s):  
Michelson Interferometer ◽  
Species Group ◽  
Reunion Island ◽  
Solar Absorption ◽  
Trace Species ◽  
Réunion Island ◽  
Peak Sensitivity ◽  
Random Uncertainties ◽  
Absorption Measurements ◽  
Good Agreement

Abstract. Profiles of CFC-11 (CCl3F), CFC-12 (CCl2F2) and HCFC-22 (CHF2Cl) have been obtained from Fourier transform infrared (FTIR) solar absorption measurements above the Saint-Denis (St Denis) and Maïdo sites at Réunion Island (21° S, 55° E) with low vertical resolution. FTIR profile retrievals are performed by the well-established SFIT4 program and the detail retrieval strategies along with the systematic/random uncertainties of CFC-11, CFC-12 and HCFC-22 are discussed in this study. The FTIR data of all three species are sensitive to the whole troposphere and the lowermost stratosphere, with the peak sensitivity between 5 and 10 km. The ground-based FTIR data have been compared with the collocated Michelson Interferometer for Passive Atmospheric Sounding (MIPAS/ENVISAT) data and found to be in good agreement: the observed mean relative biases and standard deviations of the differences between the smoothed MIPAS and FTIR partial columns (6–30 km) are (−4.3 and 4.4 %), (−2.9 and 4.6 %) and (−0.7 and 4.8 %) for CFC-11, CFC-12 and HCFC-22, respectively, which are within the combined error budgets from both measurements. The season cycles of CFC-11, CFC-12 and HCFC-22 from FTIR measurements and MIPAS data show a similar variation: concentration is highest in February–April and lowest in August–October. The trends derived from the combined St Denis and Maïdo FTIR time series are −0.86 ± 0.12 and 2.84 ± 0.06 % year−1 for CFC-11 and HCFC-22, respectively, for the period 2004 to 2016, and −0.76 ± 0.05 % year−1 for CFC-12 for 2009 to 2016. These measurements are consistent with the trends observed by the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division's (GMD) Halocarbons &amp; other Atmospheric Trace Species Group (HATS) measurements at Samoa (14.2° S, 170.5° W) for CFC-11 (−0.87 ± 0.04 % year−1), but slightly weaker for HCFC-22 (3.46 ± 0.05 %) year−1 and stronger for CFC-12 (−0.60 ± 0.02 % year−1).

scholarly journals Diurnal variations of reactive chlorine and nitrogen oxides observed by MIPAS-B inside the January 2010 Arctic vortex

2012 ◽  
Vol 12 (14) ◽  
pp. 6581-6592 ◽  
Author(s):  
G. Wetzel ◽  
H. Oelhaf ◽  
O. Kirner ◽  
F. Friedl-Vallon ◽  
R. Ruhnke ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Michelson Interferometer ◽  
Emission Spectra ◽  
The Arctic ◽  
Polar Stratospheric Clouds ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Reservoir Species ◽  
Stratospheric Clouds

Abstract. The winter 2009/2010 was characterized by a strong Arctic vortex with extremely cold mid-winter temperatures in the lower stratosphere associated with an intense activation of reactive chlorine compounds (ClOx) from reservoir species. Stratospheric limb emission spectra were recorded during a flight of the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 24 January 2010 inside the Arctic vortex. Several fast limb sequences of spectra (in time steps of about 10 min) were measured from nighttime photochemical equilibrium to local noon allowing the retrieval of chlorine- and nitrogen-containing species which change rapidly their concentration around the terminator between night and day. Mixing ratios of species like ClO, NO2, and N2O5 show significant changes around sunrise, which are temporally delayed due to polar stratospheric clouds reducing the direct radiative flux from the sun. ClO variations were derived for the first time from MIPAS-B spectra. Daytime ClO values of up to 1.6 ppbv are visible in a broad chlorine activated layer below 26 km correlated with low values (below 0.1 ppbv) of the chlorine reservoir species ClONO2. Observations are compared and discussed with calculations performed with the 3-dimensional Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). Mixing ratios of the species ClO, NO2, and N2O5 are well reproduced by the model during night and noon. However, the onset of ClO production and NO2 loss around the terminator in the model is not consistent with the measurements. The MIPAS-B observations along with Tropospheric Ultraviolet-Visible (TUV) radiation model calculations suggest that polar stratospheric clouds lead to a delayed start followed by a faster increase of the photodissoziation of ClOOCl and NO2 near the morning terminator since stratospheric clouds alter the direct and the diffuse flux of solar radiation. These effects are not considered in the EMAC model simulations which assume a cloudless atmosphere.

scholarly journals SCIAMACHY lunar occultation water vapor measurements: retrieval and validation results

2012 ◽  
Vol 5 (10) ◽  
pp. 2499-2513 ◽  
Author(s):  
F. Azam ◽  
K. Bramstedt ◽  
A. Rozanov ◽  
K. Weigel ◽  
H. Bovensmann ◽  
...  
Keyword(s):  
Water Vapor ◽  
Atmospheric Chemistry ◽  
Near Infrared ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Stratospheric Water Vapor ◽  
Lunar Occultation ◽  
Scanning Imaging

Abstract. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) lunar occultation measurements have been used to derive vertical profiles of stratospheric water vapor for the Southern Hemisphere in the near infrared (NIR) spectral range of 1350–1420 nm. The focus of this study is to present the retrieval methodology including the sensitivity studies and optimizations for the implementation of the radiative transfer model on SCIAMACHY lunar occultation measurements. The study also includes the validation of the data product with the collocated measurements from two satellite occultation instruments and two instruments measuring in limb geometry. The SCIAMACHY lunar occultation water vapor measurement comparisons with the ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument have shown an agreement of 5% on the average that is well within the reported biases of ACE in the stratosphere. The comparisons with HALOE (Halogen Occultation Experiment) have also shown good results where the agreement between the instruments is within 5%. The validations of the lunar occultation water vapor measurements with MLS (Microwave Limb Sounder) instrument are exceptionally good, varying between 1.5 to around 4%. The validations with MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) are in the range of 10%. A validated dataset of water vapor vertical distributions from SCIAMACHY lunar occultation measurements is expected to facilitate the understanding of physical and chemical processes in the southern mid-latitudes and the dynamical processes related to the polar vortex.

scholarly journals ACE-FTS observations of pyrogenic trace species in boreal biomass burning plumes during BORTAS

2012 ◽  
Vol 12 (12) ◽  
pp. 31629-31661 ◽  
Author(s):  
K. A. Tereszchuk ◽  
G. González Abad ◽  
C. Clerbaux ◽  
J. Hadji-Lazaro ◽  
D. Hurtmans ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Forest Fires ◽  
Atmospheric Composition ◽  
Fire Season ◽  
Satellite Measurement ◽  
Mixing Ratios ◽  
Trace Species ◽  
The Impact

Abstract. To further our understanding of the effects of biomass burning emissions on atmospheric composition, the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) campaign was conducted on 12 July to 3 August 2011 during the Boreal forest fire season in Canada. The simultaneous aerial, ground and satellite measurement campaign sought to record instances of Boreal biomass burning to measure the tropospheric volume mixing ratios (VMRs) of short- and long-lived trace molecular species from biomass burning emissions. The goal was to investigate the connection between the composition and the distribution of these pyrogenic outflows and their resulting perturbation to atmospheric chemistry, with particular focus on oxidant species to determine the overall impact on the oxidizing capacity of the free troposphere. Measurements of pyrogenic trace species in Boreal biomass burning plumes were made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) onboard the Canadian Space Agency (CSA) SCISAT-1 satellite during the BORTAS campaign. Even though most biomass burning smoke is typically confined to the boundary layer, emissions are often injected directly into the upper troposphere via fire-related convective processes, thus allowing space-borne instruments to measure these pyrogenic outflows. An extensive set of 15 molecules, CH3OH, CH4, C2H2, C2H6, C3H6O, CO, HCN, HCOOH, HNO3, H2CO, NO, NO2, OCS, O3 and PAN have been analyzed. Included in this analysis is the calculation of age-dependent sets of enhancement ratios for each of the species.

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