The preliminary cross-calibration of the HY-2A calibration microwave radiometer with the Jason-1/2 microwave radiometers

This article focuses on the cross-calibration of the Haiyang-2A (HY-2A) calibration microwave radiometer (CMR) with the Jason-1 microwave radiometer (JMR) and the Jason-2 advanced microwave radiometer (AMR). The temporal trends in the CMR brightness temperatures (BTs) are compared with those of the JMR and the AMR in terms of period-averaged BT (averaged over each satellite cycle). The differences between them are observed and then corrected. The data pairs at the crossover points of HY-2A and Jason-1/2 are collected. The differences between the BTs of the CMR and those of the JMR and the AMR are further reduced by a latitude correction. The validation results show that after the time and latitude corrections, the root mean square values of the BT differences are clearly reduced by about 0.8, 0.8, and 0.6 K in the three channels, respectively. Based on the time and latitude corrected data, seven kinds of retrieval model (of vapour-induced wet tropospheric path delay, water vapour, cloud liquid, and sea surface wind speed) are built for the CMR. The results of the retrieval models based on the artificial neural networks show smaller differences from the JMR and AMR data than those of the other models.