An Evaluation of FY-3C MWHS-2 at ECMWF

An Evaluation of FY-3C MWHS-2 at ECMWF
Date Published
EUMETSAT/ECMWF Fellowship Programme Research Reports
Heather Lawrence, 
S.J. English, 
AbstractThis report presents an evaluation of the quality of data from the MicroWave Humidity Sounder 2 (MWHS-2) instrument which is flown on-board the China Meteorological Administration (CMA)'s Feng Yun (FY)-3C polar orbiting satellite. This instrument has humidity sounding channels in the 183 GHz band, similar to MHS and ATMS, and new temperature sounding channels at 118 GHz. These latter channels have not been flown on a space-borne instrument before and provide an interesting new source of information. In particular they are expected to be sensitive to temperature and cloud. The data quality of MWHS-2 is evaluated for both 183 GHz and 118 GHz channels by firstly comparing observations to background radiances simulated from the ECMWF short-range forecasts. Secondly these values are compared to those from similar instruments. Finally results of experiments assimilating the 183 GHz channels in all-sky over a period of close to 6 months are presented. Results show that the 183 GHz channels of MWHS-2 are comparable to equivalent channels on ATMS and MHS, both in terms of mean observation minus background and standard deviation of observation minus background, which is indicative of similar instrument biases and noise. Furthermore results of assimilation trials for these channels show a small positive impact on short-range humidity forecasts, which is further evidence of the good quality of the data. The 118 GHz channels have global biases similar to temperature sounding channels on AMSU-A and ATMS, in most cases. The standard deviation of clear-sky observation minus background departures for MWHS-2 118 GHz channels is higher than AMSU-A or ATMS tempera- ture sounding channels, but close to the post-launch estimated noise of the MWHS-2 instrument. Striping can also be observed in maps of observation minus background for the higher peaking 118 GHz channels.