Validation of JAXA/MODIS sea surface temperature in water around Taiwan using the Terra and Aqua satellites

The research vessel-based Conductivity Temperature Depth profiler (CTD) provides underwater measurements of the bulk sea surface temperature (SST) at the depths of shallower than 5 m. The CTD observations of the seas around Taiwan provide useful data for comparison with SST of MODIS (Moderate Resolution Imaging Spectroradiometers) aboard Aqua and Terra satellites archived by JAXA (Japan Aerospace Exploration Agency). We produce a high-resolution (1 km) MODIS SST by using Multi-Channel SST (MCSST) algorithm. There were 1516 cloud-free match-up data pairs of MODIS SST and in situ measurements during the period from 2003 - 2005. The difference of the root mean square error (RMSE) of satellite observations from each platform during the day and at night was: 0.88°C in Aqua daytime, 0.71°C in Aqua nighttime, 0.71°C in Terra daytime, and 0.60°C in Terra nighttime. The total analysis of MODIS-derived SST shows good agreement with a bias of 0.03°C and RMSE of 0.75°C. The analyses indicate that the bias of Aqua daytime was always positive throughout the year and the large RMSE should be attributed to the large positive bias (0.45°C) under diurnal warming. It was also found that the bias of Terra daytime was usually negative with a mean bias of -0.41°C; its large RMSE should be treated with care because of low solar radiation in the morning. Key word: SST, Taiwan, MODIS, Satellite observation