Investigation on Calibration and Validation for FY-3 Series Microwave Humidity Sounders

Abstract

The MWHTS onboard FY-3C/D/E satellite has 15 channels at frequencies ranging from 89-191GHz, which allows simultaneous retrieval of the atmospheric temperature and humidity profiles with good temporal and spatial sampling under all weather and all day. On-orbit, without the benefit of known calibration sources at intermediate brightness temperatures (such as were available during T/V testing), it is not possible to directly measure the nonlinearity. But, the nonlinearity correction is a function of the physical temperature of the detectors. So, on-orbit, we will rely on temperature readings from temperature sensors located near the detectors to determine the correction values to apply. Depending on the magnitude of the estimated nonlinearity and its rate of change, a decision can be made regarding how often the correction value needs to be updated. This has potential implications for climate data records.