Publications

Sandamali, GAJ; Thilakarathne, EPDN; Jayarathna, WNDS; Abeygunawardana, AP; Warnasuriya, TWS; Egodauyana, KPUT (2023). Chlorophyll-a variability in different zones of the Indian Ocean around Sri Lanka concerning monsoon patterns and sea surface temperature. REGIONAL STUDIES IN MARINE SCIENCE, 61, 102904.

Abstract
This study aims to investigate the CHL-a variability in the entire oceanic area of Sri Lanka concerning different monsoon patterns, maritime zones, and the influence of SST and Indian Ocean Dipole (IOD) using the chlorophyll-a (CHL-a) and sea surface temperature (SST) data obtained through the Moderate Resolution Imaging Spectroradiometer (MODIS). Obtained data were analyzed for three depth zones (continental shelf, 1000 m & 2000 m), two legalized zones (territorial Sea & Exclusive Economic Zone -EEZ), and five different climatic regions around the Island. There were significantly different (p < 0.05) mean CHL-a and SST values concerning various depth zones, legalized zones, and climatic regions with the four different monsoon periods. By considering the entire study area, the highest mean CHL-a value (3.878 mg m-3) with the lowest mean SST value (22.74 degrees C) was observed during the southwest monsoon (SWM) in the continental shelf (<100 m) off Southern Sri Lanka. The lowest mean CHL-a (0.12 mg m-3) was found within the EEZ in the first inter-monsoon (IM-1). Mean CHL-a values were always reduced towards the open ocean as the continental shelf, territorial sea, 1000 m zone, 2000 m zone, and EEZ consecutively in all climatic regions which strongly indicates due to nutrients drained from terrestrial runoff and induced upwelling during the activated monsoon patterns. Within the demarcated upwelling zone off the Southern coast of Sri Lanka, upwelling was prominent during the SWM, and CHL-a in the upwelling zone showed a significantly (p < 0.05) negative correlation with SST and IOD, and a significantly positive (p < 0.05) correlation with wind speed. (c) 2023 Elsevier B.V. All rights reserved.

DOI:
10.1016/j.rsma.2023.102904

ISSN: