Coastal upwelling activity along the central east coast of India

Abstract

High primary productivity along the central east coast of India is usually related to coastal upwelling activity that injects nutrients into the euphotic zone in response to prevailing longshore winds. The upwelling process has maximum intensity during March and August-September, with the coastal upwelling index varying from 10 to 150 m3/s per 100 m of coastline. Along the entire coast of the peninsula, the upwelling intensity changes in accordance with local wind conditions. I have identified the seasonal and synoptic variability of upwelling signatures on the central east coast of India, using averaged monthly and weekly sea surface temperature (SST) distributions obtained from remote sensing imagery from the Advanced Very High Resolution Radiometer in the period from 2000 to 2003. Analyse the seasonal mean variability of the upwelling-forced conditions, the average monthly PFEL coastal upwelling index (CUI) for 1990 through 2003 have been calculated for the entire central east coast with latitude resolution of 0.5°, attending to the local coastline orientation for each point. The index also shows a near-perfect confirmation of both the upwelling intensification during March, and the decrease of upwelling-favorable conditions towards the south. Spectra calculated using entire time series of from 2000 to 2003 wind data show that the frequency ranges from 0.1 to 0.2 cycles/day (corresponding to periods of 5 to 10 days) and has a number of significant energy peaks. The presence of energy frequency ranges from 0.1 to 0.2 cycles/day became evident, especially for the Visakhapatnam and Chennai stations.