CHARACTERISTICS OF SEA SURFACE TEMPERATURE ERRORS IN THE NORTHWEST PACIFIC USING MICROWAVE SATELLITES

摘要

The accuracy and error characteristics of microwave Sea Surface Temperature (SST) measurements in the Northwest Pacific were analysed using the GMI sensor data of currently operated GPM satellite and AMSR2 sensor data of GCOM-W1. The data of matchup points between each sensor data and oceanic in-situ temperature measurements were produced from the launch date of each sensor to August 2016. The AMSR2 SST and GMI SST measurements had a Root-Mean-Square (RMS) error of about 0.63C and 1.46C and a bias error of about 0.05C and 0.34C, respectively. The SST differences between microwave SST and in-situ measurements were caused by various factors, such as wind speed, SST, distance from the coast, and the thermal front. The microwave SST data showed an error due to the diurnal effect, which was much higher than the in-situ temperature measurements at low wind speed (<6 m/s) during the daytime. In addition, the RMS error tended to be large in the winter because the emissivity of the sea surface was increased by high wind speeds and it could induce positive deviation in the SST retrieval. Low sensitivity at colder temperature and land contamination also affected an increase in the error of microwave SST. An analysis of the effect of the thermal front on satellite SST error indicated that SST error increased as the magnitude of the spatial gradient of the SST increased and the distance from the front decreased. The GMI SST tended to show a large error at high latitudes due to the cold water temperature.