Distribution of chlorophyll-a and sea surface temperature (SST) using modis data in east Kalimantan waters, Indonesia

Abstract

Regular monitoring of near-shore and open-water parameters for marine management in East Kalimantan waters, Indonesia is still limited. The objective of this research is to determine and interpret the seasonal and spatial variability of sea surface temperature (SST) and Chlorophyll-a concentration (Chl-a) in East Kalimantan waters. A standard MODIS SST split-window algorithm and empirical Chlorophyll-a 0C-3M algorithm were used to generate the Level 2 MODIS SST and Chl-a images. MODIS or Moderate Resolution Imaging Spectroradiometer is a key instrument aboard the Terra and Aqua satellites. From March 2005 to August 2006, the SST and Chl-a were retrieved from the sensor data in East Kalimantan coastal and open-sea waters. In situ measurements from near-shore waters were used to validate the MODIS Level 2 data. A comparison of MODIS with in situ values for SST and Chl-a shows: RMSE=1.21°C, Bias=-3.42, n=121 and RMSE=1.01mg.m -3 , Bias=+2.45, n=75, although some anomalies were observed in the retrievals in both datasets. The analysis of seasonal variations indicates that there was low SST variability between wet and dry season. There was also low variability between SST values in near-shore and open-sea waters. However, for both seasons, open-sea SST was paradoxically found to be warmer than the near-shore waters. The Chl-a maps revealed low Chl-a variability between wet and dry season. Different value ranges in Chl-a were found between near-shore waters (1.00-56.00 mg.n -3 ) and open waters (1.00-4.00 mg.n -3 ). The Chl-a values retrieved from MODIS for both seasons were higher in near-shore water. The SST and Chl-a in near-shore waters have a low positive interrelationship in wet season. During dry season, the relationship between these two variables varies from positive to negative. This study demonstrated that MODIS Level 2 data from Malaysia Ground Receiving Station (MGRS) can successfully be used to obtain SST and Chl-a in Southeast Asian coastal and open waters