Variability of Chlorophyll-a and SST at Regional Seas Level in Thai Waters using Satellite Data

Abstract

Satellite-derived measurements were used to investigate the spatial and temporal variability of chlorophyll-a (Chl-a) and sea surface temperature (SST) at Regional Seas level in Thai waters. As case study, the Gulf of Thailand and Andaman Sea were selected as areas of interest (AOI). The monthly data with 4 km spatial resolution of Chl-a and SST ocean color images from January 2003 to December 2009 were collected from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR), respectively. Chl-a concentration was relatively low during summer, while in winter Chl-a concentration increased and its relationship was inversely proportional with SST. The lowest Chl-a concentration was in August 2005 (0.33 mg m^-3), while the highest was in December 2006 (0.96 mg m^-3). The lowest SST was in January 2009 (27.12 °C) and the highest was in May 2005 (31.00 °C). Chl-a concentration has an important economic effect on coastal and marine environments in terms of fisheries resources and marine aquaculture development. Current direction and wind condition should be taken into account for further spatial and temporal studies of Chl-a and SST. Moreover, the influence by suspended sediments caused by re-suspension or river discharge could be a major factor in the variation of chlorophyll along the coast. Therefore, understanding the spatial and temporal patterns of the Chl-a concentration is very important particularly for oceanography and fishery management. This study provides baseline information for future research in marine ecosystem-based approach for sustainable fisheries management in this region.