Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study
We report on the dependence of ozone volume mixing ratio profiles, retrieved from limb emission infrared spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as the treatment of the background continuum, cloud filtering, spectral regio...
Main Authors: | , , , , , , , , , , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2006-01-01
|
Series: | Atmospheric Chemistry and Physics |
Online Access: | http://www.atmos-chem-phys.net/6/2767/2006/acp-6-2767-2006.pdf |
id |
doaj-8832a7ade3f04783982975788a66f401 |
---|---|
record_format |
Article |
spelling |
doaj-8832a7ade3f04783982975788a66f4012020-11-24T20:44:04ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242006-01-0161027672781Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity studyN. GlatthorT. von ClarmannH. FischerB. FunkeS. Gil-LópezU. GrabowskiM. HöpfnerS. KellmannA. LindenM. López-PuertasG. Mengistu TsiduG. Mengistu TsiduM. MilzT. SteckG. P. StillerD.-Y. WangD.-Y. WangWe report on the dependence of ozone volume mixing ratio profiles, retrieved from limb emission infrared spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as the treatment of the background continuum, cloud filtering, spectral regions used for analysis and a series of further more technical parameter choices. The purpose of this investigation is to better understand the error sources of the ozone retrieval, to optimize the current retrieval setup and to document changes in the data versions. It was shown that the cloud clearing technique used so far (cloud index 1.8) does not reliably exclude all cloud-contaminated spectra from analysis. Through analysis of spectra calculated for cloudy atmospheres we found that the cloud index should be increased to a value of 3.0 or higher. Further, it was found that assignment of a common background continuum to adjacent microwindows within 5 cm<sup>−1</sup> is advantageous, because it sufficiently represents the continuum emission by aerosols, clouds and gases as reported in the literature, and is computationally more efficient. For ozone retrieval we use ozone lines from MIPAS band A (685–970 cm<sup>−1</sup>) and band AB (1020–1170 cm<sup>−1</sup>) as well. Therefore we checked ozone retrievals with lines from bands A or AB only for a systematic difference. Such a difference was indeed found and could, to a major part, be attributed to the spectroscopic data used in these two bands, and to a minor part to neglection of modelling of non-local thermodynamic (non-LTE) emissions. Another potential explanation, a bias in the radiance calibration of level-1B spectra of bands A and AB, could largely be ruled out by correlation analysis and inspection of broadband spectra. Further upgrades in the ozone retrieval consist of application of an all-zero a-priori profile and a weaker regularization. Finally, the ozone distribution obtained with the new retrieval setup (data versions V3o_O3_7) was compared to the data version used before (V2_O3_2). Differences are smaller than $pm$0.4 ppmv in the altitude region 15–50 km. Further, differences to ozone measured by the HALogen Occultation Experiment (HALOE) on the Upper Atmospheric Research Satellite (UARS) are partly reduced with the new MIPAS data version.http://www.atmos-chem-phys.net/6/2767/2006/acp-6-2767-2006.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
N. Glatthor T. von Clarmann H. Fischer B. Funke S. Gil-López U. Grabowski M. Höpfner S. Kellmann A. Linden M. López-Puertas G. Mengistu Tsidu G. Mengistu Tsidu M. Milz T. Steck G. P. Stiller D.-Y. Wang D.-Y. Wang |
spellingShingle |
N. Glatthor T. von Clarmann H. Fischer B. Funke S. Gil-López U. Grabowski M. Höpfner S. Kellmann A. Linden M. López-Puertas G. Mengistu Tsidu G. Mengistu Tsidu M. Milz T. Steck G. P. Stiller D.-Y. Wang D.-Y. Wang Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study Atmospheric Chemistry and Physics |
author_facet |
N. Glatthor T. von Clarmann H. Fischer B. Funke S. Gil-López U. Grabowski M. Höpfner S. Kellmann A. Linden M. López-Puertas G. Mengistu Tsidu G. Mengistu Tsidu M. Milz T. Steck G. P. Stiller D.-Y. Wang D.-Y. Wang |
author_sort |
N. Glatthor |
title |
Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study |
title_short |
Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study |
title_full |
Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study |
title_fullStr |
Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study |
title_full_unstemmed |
Retrieval of stratospheric ozone profiles from MIPAS/ENVISAT limb emission spectra: a sensitivity study |
title_sort |
retrieval of stratospheric ozone profiles from mipas/envisat limb emission spectra: a sensitivity study |
publisher |
Copernicus Publications |
series |
Atmospheric Chemistry and Physics |
issn |
1680-7316 1680-7324 |
publishDate |
2006-01-01 |
description |
We report on the dependence of ozone volume mixing ratio profiles, retrieved from limb emission infrared spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on different retrieval setups such as the treatment of the background continuum, cloud filtering, spectral regions used for analysis and a series of further more technical parameter choices. The purpose of this investigation is to better understand the error sources of the ozone retrieval, to optimize the current retrieval setup and to document changes in the data versions. It was shown that the cloud clearing technique used so far (cloud index 1.8) does not reliably exclude all cloud-contaminated spectra from analysis. Through analysis of spectra calculated for cloudy atmospheres we found that the cloud index should be increased to a value of 3.0 or higher. Further, it was found that assignment of a common background continuum to adjacent microwindows within 5 cm<sup>−1</sup> is advantageous, because it sufficiently represents the continuum emission by aerosols, clouds and gases as reported in the literature, and is computationally more efficient. For ozone retrieval we use ozone lines from MIPAS band A (685–970 cm<sup>−1</sup>) and band AB (1020–1170 cm<sup>−1</sup>) as well. Therefore we checked ozone retrievals with lines from bands A or AB only for a systematic difference. Such a difference was indeed found and could, to a major part, be attributed to the spectroscopic data used in these two bands, and to a minor part to neglection of modelling of non-local thermodynamic (non-LTE) emissions. Another potential explanation, a bias in the radiance calibration of level-1B spectra of bands A and AB, could largely be ruled out by correlation analysis and inspection of broadband spectra. Further upgrades in the ozone retrieval consist of application of an all-zero a-priori profile and a weaker regularization. Finally, the ozone distribution obtained with the new retrieval setup (data versions V3o_O3_7) was compared to the data version used before (V2_O3_2). Differences are smaller than $pm$0.4 ppmv in the altitude region 15–50 km. Further, differences to ozone measured by the HALogen Occultation Experiment (HALOE) on the Upper Atmospheric Research Satellite (UARS) are partly reduced with the new MIPAS data version. |
url |
http://www.atmos-chem-phys.net/6/2767/2006/acp-6-2767-2006.pdf |
work_keys_str_mv |
AT nglatthor retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT tvonclarmann retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT hfischer retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT bfunke retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT sgilloacutepez retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT ugrabowski retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT mhopfner retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT skellmann retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT alinden retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT mloacutepezpuertas retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT gmengistutsidu retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT gmengistutsidu retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT mmilz retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT tsteck retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT gpstiller retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT dywang retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy AT dywang retrievalofstratosphericozoneprofilesfrommipasenvisatlimbemissionspectraasensitivitystudy |
_version_ |
1716818433735131136 |