The MicroWave Humidity Sounder-II (MWHS-II) is an important instrument onboard FengYun-3C (FY-3C), the first operational satellite in a series of the second generation of polar-orbiting operational meteorological satellites of China.
The MWHS-II on FY-3C and future FY-3s is an improved version of early MWHS model that fly on FY-3A/B. Additional eight channels in 118-GHz band and a 89-GHz channel are added to the MWHS-I.
MWHS-II was designed for observing the distribution of global atmospheric thermodynamics information, and monitoring the severe convective systems such as typhoon and rainstorm in all-weather conditions. Assimilation of MWHS-II will improve the analysis of atmospheric humidity and temperature fields required for numerical weather prediction (NWP).
MWHS-II is a total power microwave radiometer, which has fifteen channels in the range 89-191GHz. Five sounding channels have center frequency at 183.31GHz water vapor absorption line, each having two pass-bands. Eight sounding channels have center frequency at 118.75GHz oxygen absorption line. Two window channels are at 89GHz and 150GHz.
In the normal working mode for MWHS-II on orbit, two offset-fed parabolic antennas are perpendicular to flight track. MWHS-II performs cross-track scanning with a swath of 2700 km. The incident microwave radiation is fed to corrugated feed horn via reflectors, then the beam is split by a quasi-optical system into required frequency bands for 118 and 183GHz to obtain the observation expressed in the form of counts. Each receiver is operated in double sideband mode to improve the sensitivity.
|Satellite||FY-3C , FY-3D , FY-3E|
|Spatial Resolution||16km (183GHz) / 32km (other)|
|Channel||Central frequency (GHz)||Polarisations||Bandwidth (MHz)||Frequency stability (MHz)||Dynamic range (K)||NEΔT (K)||Calibration Bias (K)||Antenna main beam width||Antenna main beam efficiency|
|FY-3D||MWHS-II||L1 data, L2L3 product|
|FY-3C||MWHS-II||L1 data, L2L3 product|
MWHS-II calibration and validation