The information content of clear sky IASI radiances and their potential for numerical weather prediction
Version of Record online: 15 DEC 2006
Copyright © 1998 Royal Meteorological Society
Quarterly Journal of the Royal Meteorological Society
Volume 124, Issue 545, pages 211–241, January 1998 Part A
How to Cite
Prunet, P., Thépaut, J.-N. and Cassé, V. (1998), The information content of clear sky IASI radiances and their potential for numerical weather prediction. Q.J.R. Meteorol. Soc., 124: 211–241. doi: 10.1002/qj.49712454510
- Issue online: 15 DEC 2006
- Version of Record online: 15 DEC 2006
- Manuscript Revised: 25 MAR 1997
- Manuscript Received: 11 NOV 1996
- Analysis error;
- Humidity profiles;
- Remote sensing;
- Satellite-data retrieval;
- Temperature profiles
The estimation-error covariance matrix associated with the analysis of the atmospheric state is used in one particular meteorological situation to examine the potential benefit of radiance data for numerical weather prediction. The gain of information content obtained from simulated Infrared Atmospheric Sounding Interferometer (IASI) data is studied and compared with the current information present in the TIROS Operational Vertical Sounder (TOVS) radiances.
Nineteen independent items of information on a typical temperature/humidity profile are available from the IASI data, compared to six from the TOVS data. In terms of temperature, fine-scale structures associated with a vertical resolution of 1 km are estimated with a 0.7 K error standard deviation. The gain of information for specific humidity is of the same order of magnitude as for temperature. Typically, humidity structures associated with 1 km vertical resolution are estimated with a relative error of 16%.
The projection of the analysis-error covariance matrix on atmospheric-error structures (relevant for numerical weather prediction) gives a measure of the impact of the use of radiances on the observability of such structures. The results indicate that IASI data would be a decisive source of information for the analysis of such structures.
Finally, a preliminary sensitivity study suggests that the degradation due to radiance noise associated with possible modifications of the IASI instrument, hardly affects the quality of the analysis.