Wind tracing with ozone-sensitive radiances from SEVIRI

Title
Wind tracing with ozone-sensitive radiances from SEVIRI
Report
Date Published
12/2013
Series/Collection
EUMETSAT/ECMWF Fellowship Programme Research Reports
Document Number
31
Author
Cristina Lupu
A. McNally
Event Series/Collection
EUMETSAT/ECMWF Fellowship Programme
Abstract Ozone-sensitive radiances from SEVIRI have been recently evaluated within the ECMWF operational system, both in terms of possibility of wind extraction from the 4D-Var assimilation and in terms of impact on analysis and forecast. To illustrate the effect of ozone feature tracing in the 4D-Var, experiments have been performed at ECMWF where the dynamical link between the ozone and the rest of the system has been deliberately enabled or disabled. The findings of this investigation show that, if the dynamical link between the ozone and the rest of the system is enabled, the 4D-Var has the freedom to change the temperature and wind fields, as well as the ozone field itself in order to improve the fit to observed ozone concentrations. SEVIRI ozone-sensitive observations, via passive tracing, provide a potentially useful constraint upon the analysis of wind, particularly in the upper troposphere and lower stratosphere. When added to an observation depleted baseline experiments, SEVIRI ozone-sensitive radiances changed the ozone analysis around 150 hPa and this improved the fit to MLS ozone data. The wind analyses scores are improved around 150 hPa, but the improvement is small when compared with the wind analysis scores from humidity-sensitive clear-sky radiances. When added to the full observing system, SEVIRI ozone-sensitive radiances slightly improves the fit to other infrared ozone-sensitive radiances, but the improvement is not visible in the fit to MLS. The wind analysis and forecast impact results do not suggest benefit on improving the ECMWF wind field.
URL https://www.ecmwf.int/en/elibrary/75484-wind-tracing-ozone-sensitive-radiances-seviri
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