Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model
Accurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. We consider a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE) in combination wi...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-01-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/14/177/2014/acp-14-177-2014.pdf |
| _version_ | 1828156170100015104 |
|---|---|
| author | E. Emili B. Barret S. Massart E. Le Flochmoen A. Piacentini L. El Amraoui O. Pannekoucke D. Cariolle |
| author_facet | E. Emili B. Barret S. Massart E. Le Flochmoen A. Piacentini L. El Amraoui O. Pannekoucke D. Cariolle |
| author_sort | E. Emili |
| collection | DOAJ |
| description | Accurate and temporally resolved fields of free-troposphere ozone are of
major importance to quantify the intercontinental transport of pollution and
the ozone radiative forcing. We consider a global chemical transport model
(MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE) in
combination with a linear ozone chemistry scheme to examine the impact of
assimilating observations from the Microwave Limb Sounder (MLS) and the
Infrared Atmospheric Sounding Interferometer (IASI). The assimilation of the
two instruments is performed by means of a variational algorithm (4D-VAR) and
allows to constrain stratospheric and tropospheric ozone simultaneously. The
analysis is first computed for the months of August and November 2008 and
validated against ozonesonde measurements to verify the presence of
observations and model biases. Furthermore, a longer analysis of 6 months
(July–December 2008) showed that the combined assimilation of MLS and IASI is
able to globally reduce the uncertainty (root mean square error, RMSE) of the
modeled ozone columns from 30 to 15% in the
upper troposphere/lower stratosphere (UTLS, 70–225 hPa). The assimilation of
IASI tropospheric ozone observations (1000–225 hPa columns, TOC – tropospheric O<sub>3</sub> column)
decreases the RMSE of the model from 40 to 20% in the tropics
(30° S–30° N), whereas it is not effective at higher latitudes.
Results are confirmed by a comparison with additional ozone data sets like the
Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC)
data, the Ozone Monitoring Instrument (OMI) total ozone columns and several
high-altitude surface measurements. Finally, the analysis is found to be
insensitive to the assimilation parameters. We conclude that the combination
of a simplified ozone chemistry scheme with frequent satellite observations
is a valuable tool for the long-term analysis of stratospheric and
free-tropospheric ozone. |
| first_indexed | 2024-04-11T23:06:02Z |
| format | Article |
| id | doaj.art-3bd2360aee404e3a93b207aa63ee6718 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-11T23:06:02Z |
| publishDate | 2014-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-3bd2360aee404e3a93b207aa63ee67182022-12-22T03:58:00ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242014-01-0114117719810.5194/acp-14-177-2014Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport modelE. Emili0B. Barret1S. Massart2E. Le Flochmoen3A. Piacentini4L. El Amraoui5O. Pannekoucke6D. Cariolle7CERFACS and CNRS, URA1875, Toulouse, FranceLaboratoire d'Aérologie/OMP, Université de Toulouse and CNRS, UMR5560, Toulouse, FranceECMWF, Reading, UKLaboratoire d'Aérologie/OMP, Université de Toulouse and CNRS, UMR5560, Toulouse, FranceCERFACS and CNRS, URA1875, Toulouse, FranceCNRM-GAME, Météo-France and CNRS, UMR3589, Toulouse, FranceCERFACS and CNRS, URA1875, Toulouse, FranceCERFACS and CNRS, URA1875, Toulouse, FranceAccurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. We consider a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE) in combination with a linear ozone chemistry scheme to examine the impact of assimilating observations from the Microwave Limb Sounder (MLS) and the Infrared Atmospheric Sounding Interferometer (IASI). The assimilation of the two instruments is performed by means of a variational algorithm (4D-VAR) and allows to constrain stratospheric and tropospheric ozone simultaneously. The analysis is first computed for the months of August and November 2008 and validated against ozonesonde measurements to verify the presence of observations and model biases. Furthermore, a longer analysis of 6 months (July–December 2008) showed that the combined assimilation of MLS and IASI is able to globally reduce the uncertainty (root mean square error, RMSE) of the modeled ozone columns from 30 to 15% in the upper troposphere/lower stratosphere (UTLS, 70–225 hPa). The assimilation of IASI tropospheric ozone observations (1000–225 hPa columns, TOC – tropospheric O<sub>3</sub> column) decreases the RMSE of the model from 40 to 20% in the tropics (30° S–30° N), whereas it is not effective at higher latitudes. Results are confirmed by a comparison with additional ozone data sets like the Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC) data, the Ozone Monitoring Instrument (OMI) total ozone columns and several high-altitude surface measurements. Finally, the analysis is found to be insensitive to the assimilation parameters. We conclude that the combination of a simplified ozone chemistry scheme with frequent satellite observations is a valuable tool for the long-term analysis of stratospheric and free-tropospheric ozone.http://www.atmos-chem-phys.net/14/177/2014/acp-14-177-2014.pdf |
| spellingShingle | E. Emili B. Barret S. Massart E. Le Flochmoen A. Piacentini L. El Amraoui O. Pannekoucke D. Cariolle Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model Atmospheric Chemistry and Physics |
| title | Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model |
| title_full | Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model |
| title_fullStr | Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model |
| title_full_unstemmed | Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model |
| title_short | Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model |
| title_sort | combined assimilation of iasi and mls observations to constrain tropospheric and stratospheric ozone in a global chemical transport model |
| url | http://www.atmos-chem-phys.net/14/177/2014/acp-14-177-2014.pdf |
| work_keys_str_mv | AT eemili combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT bbarret combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT smassart combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT eleflochmoen combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT apiacentini combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT lelamraoui combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT opannekoucke combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel AT dcariolle combinedassimilationofiasiandmlsobservationstoconstraintroposphericandstratosphericozoneinaglobalchemicaltransportmodel |