Assessment and Validation of Microwave Humidity and Temperature Sounder Onboard FY-3C

The paper introduces the design and development of MWHTS system and quantitatively evaluates the stability of its post-launch performance (3 years and 3 months). The on-orbit assessment of MWHTS demonstrates that the MWHTS onboard FY-3C has been improved compared to it on FY-3A and FY-3B. Furthermore, using the observing data from MTHTS shows that the instrument plays an important role in monitor extreme climate, especially for typhoon between June to Sept in 2016, including the procedure of generating, evolution, strengthen and die out, and also including the heavy rainfall caused by typhoon, which is compared against ground-based observations (gauge) and products blended by sensors onboard TRMM and GPM.

The Microwave Humidity and Temperature Sounder, MWHTS has been worked on 30 September 2013 to fly on the new generation of FengYun polar orbiters, which is named FY-3C. MWHTS with 15 channels in the range of 89-190GHz is designed for atmospheric humidity and temperature sounding, and also for monitoring severe weather systems such as typhoons and rainstorms. Compared to microwave humidity sounder (MWHS) onboard FY-3B , MWHTS improves channel characteristics by adding 8 horizontal polarized channels near 118.75 GHz, which is the first operational polar orbiting satellite-based sensor to observe atmosphere in earth-scanning mode in the 118 GHz oxygen band. Also, MWHTS has5 channels at 183 GHz.

NCEP datasets(per 6 hours) from January, 1, 2014 to Oct, 31, 2014are chosen to run the Weather Research and Forecast model WRF, and derive the typical precipitation data from the whole world, especially for the extreme weather, such as typhoon, cyclone and rainfall. Bring out the incomplete cases and latitude values smaller than 0 degree and larger than 30 degree. Then among the datasets, the cases which satisfy the threshold that precipitation rate larger than 1mm/h are valid.

As a valid prediction of typhoon movement, the vertical temperature information was used to analyze the relationship between the abnormal temperature increase around the typhoon center and the movement direction of the typhoon in the following hours. No.1617 and No.1618 named Haima and Sarika were both the landing typhoon happened in northwestern Pacific, they came one by one with different walking path, and the landing points were also different. By using the FY-3C 118GHz data, the calculation results show that before and after these two typhoons landing, their environmental circulation around typhoons was warmer region , that is the positive temperature anomaly region, this area position was the corresponding with typhoon movement trend.

FY-3C MWHTS as a passive microwave radiometer has been operated for more than 3 years, which has been assimilated in ECMWF mode, where the data continues to be of good quality and no major issues have been identified. The performance of in-orbit is qualified and some applications have been researched and applied by meteorological researchers to predict extreme weather as ATMS and MHS, which are standard payload to sound temperature and humidity profiles.