Sensitivity Study for 183.31-GHZ Channels of the FY-3E/MWHTS Spectral Response Functions

In the calibration of Microwave Humidity and Temperature Sounder (MWHTS) onboard the Fengyun-3E (FY-3E) satellite, the ideal rectangular spectral response function is normally used. However, the measured spectral response function has in-band fluctuation, which will not only cause errors to the calibration, but also is essential to the subsequent data retrieval and assimilation applications. In this paper, the spectral response function (SRF) of five channels located near the frequency of 183.31-GHz is studied. The results demonstrate that different channels have different responses to the measured SRF and the ideal rectangular SRF. The closer the channel is the frequency 183.31-GHz, the maximum deviation is nearly 0.2 K. In addition, a constant noise, uniform noise, Gaussian noise and Chebyshev 1 ripple noise were added respectively. The greater the noise amplitude, the greater the brightness temperature deviation, and the results of four different noise was consistent. When the noise amplitude is set to 3 dB, the brightness temperature deviation reaches 0.1 K. The results can not only provide reference for the design of the sensor, but also provide a new idea for data calibration, so as to improve the accuracy of data calibration.