Seasonal variation of sea surface temperature in the Bay of Bengal during 1992 as derived from NOAA-AVHRR SST data

Abstract

Monthly maps of sea surface temperature (SST) derived for NOAA (National Oceanic and Atmospheric Administration)-AVHRR (Advanced Very High Resolution Radiometer) data during 1992 for the Bay of Bengal are analysed and compared with the available/ compiled monthly seatruth (bucket thermometer) data of this region. It was noticed that the computed SST bias (AVHRR SST minus Seatruth SST), in general, varied between -2.0 degrees and 2.5 degrees C with smaller bias values (-1.5 degrees to 1.5 degrees C) during January-June and December. Larger bias values were noticed in the south-eastern Bay in July and in the Andaman Sea in October. The large SST biases suggested the necessity for improvement of SST algorithms by properly removing the clouds. The spatial variation of Standard Deviation of SST bias was particularly high (less than 0.7) in the western Bay when compared to other parts of the Bay of Bengal. The monthly maps of AVHRR SST clearly depicted the seasonal cycle of SST showing the well known bi-modal SST distribution of the study region with winter cooling, summer heating, monsoonal cooling and post-monsoon warming phases. The seasonal cycle of SST further revealed the persistence of Warm Pool (SST greater than or equal to 28 degrees C) in the Bay of Bengal from March through October