|Title||A study on the spectral and radiometric specifications of a post-EPS microwave imaging mission|
|Publication Type||Technical memorandum|
|Secondary Title||ECMWF Technical Memorandum|
|Authors||Peubey, C, Bell, W, Bauer, P, Di Michele, S|
This study contributes to the specification of EUMETSAT's post-EPSMicrowave Imager and Sounder missions and makes use of tools developed as part of previous similar studies at ECMWF, including 1D-Var and information content analyses as well as observing system experiments. The sensitivity of analysis and forecast errors to spectral shifts in microwave channels was investigated. The maximum tolerable drift for temperature sounding channels has been found to be around 1.5 MHz. The use of a variational correction scheme significantly reduced the negative impact of larger drifts. Cross polarisation errors were shown to cause biases in retrieved ocean surface wind speed (10%) and column water vapour (3%). The specification of channels in the range 15-22 GHz and 31-37 GHz, given radio frequency protection issues, was investigated. A framework for the quantitative analysis of resolution and sampling strategies was developed, based on linear estimation theory and using entropy reduction as a figure of merit. The capability of digital detection (spectrally resolved microwave radiometry) to reproduce conventional analog passbands was investigated. Finally data from F18 SSMIS, the third in a series of five combined imager-sounder instruments, was assessed through observing system experiments as part of an ongoing assessment of the potential for combined imaging and sounding.