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| Titel |
4D-var assimilation of CRISTA-NF H2O and MLS retrievals with the high resolution SACADA system |
| VerfasserIn |
Ketevan Kasradze, Hendrik Elbern, Jörg Schwinger |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042782
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| Zusammenfassung |
| SACADA is a 4-dimensional variational assimilation system for trace gas observations. A novel global chemistry transport model with its adjoint version is the kernel of this system. Since the German Weather Service global forecast model (GME) is used as an online meteorological driver, the icosahedral grid structure and the horizontal transport are adopted from GME. Recently the horizontal and vertical scheme resolution of the model grid was refined: The distance of the horizontal grid points was reduced to about 150 km and vertical separation between grid levels is now less then 1 km below 22 km altitude. In order to better describe chemical processes in the lower stratosphere/upper troposphere (UT/LS) the chemistry module was extended and revised. All this modifications were done in order to draw full advantage from high resolution limb sounding instruments, like CRISTA-NF (Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere - New Frontiers).
As a case study, assimilation of MLS (Microwave Limb Sounder) data with diagnosis of observation and background error statistics in observation space for H2O was performed. Relative humidity is used to filter observations and the background field. It is shown that the H2O analysis significantly improves compared to the ECMWF operational analisys. Additionally, data from the CRISTA-NF instrument, which has been operated on board the Russian high altitude research aircraft M-55 Geophysica, was assimilated. These CRISTA-NF observations have been taken during the AMMA (African Mansoon Measurements Analysis) Campaign in summer 2006 by ICG I (Institute of Chemistry and Dynamics of the Geosphere, Research Centre Jülich). A basic finding is that the H2O-analysis based on the additional CRISTA data in the UT/LS region improves with the SACADA high resolution configuration. |
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