INTER-ANNUAL VARIABILITY OF Chlorophyll-a AND IMPACT OF EXTREME CLIMATIC EVENTS ALONG THE SOUTH-WEST COAST OF INDIA

The inter-annual variability of Chlorophyll-a (Chl-a) along the South Eastern Arabian Sea (SEAS) has been studied during 1998 to 2016 using various satellite data products. The monthly data for Chl-a, Sea Surface Temperature (SST), Sea Level Anomaly (SLA) and Ekman Mass Transport (EMT) were analysed to explore the possible causative factors influencing the variability in Chl-a. The Hovmoller analysis of Chl-a revealed inter-annual variability and it is concurrent with the above mentioned environmental variables (Figure 1). The occurrence of extreme climatic events such as El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) were noticed during the study period. The SST anomaly derived from monthly SST data showed an increasing trend after 2012 that also reflected in the Chl-a concentration along the coast of SEAS. There is a major change of nearly 2- 2.5 ^OC in the SST anomaly during 2015-2016 which coincide with ENSO event. During this period, a considerable decrease in Chl-a concentration has also been observed. An alteration in the Walker circulation pattern during ENSO event and unusual warming during IOD events results variability in coastal dynamics along the west coast of India. This changes probably will have an impact on Chl-a in the coastal waters of SEAS.