Numerical modeling of eddies in the gulf of Thailand comparing with satellite remote sensing data

Abstract

Eddies in the Gulf of Thailand were studied using numerical ocean model in conjunction with satellite remote sensing. Princeton Ocean Model with 10-km spatial resolution was driven by combined 12-hour wind stress from Navy Operational Global Atmosphere Prediction System and 4 principal tidal constituents, M2, S2, K1 and O1 at open boundaries for the period between January 2000 to February 2001. Anticyclonic eddies and cyclonic eddies of 100 to 200 km spatial-scale are found. Eddies time scales are in the order of 2 days to 2 weeks. There are two main areas where eddies are recurrent. The first one locates at approximately between latitude 10-11 ํN and longitude 101-102 ํE. The other locates at approximately between latitude 8-9 ํN and longitude 101.5-102.5 ํE. Both areas lie in the middle of the Gulf where bottom depth exceeding 60 m. Numerical experiments show that wind is the major contributor to eddy generation in the Gulf of Thailand, while tide is not essential to eddy generation. However, interaction between wind and tide may account for the location and scale of eddies. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) level 1A HRPT data of the concurrent period were analyzed for chlorophyll_a concentration according to standard Ocean Chlorophyll 4 algorithm. Eddy is not detected from those images due to high cloud cover over the region and low chlorophyll_a concentration in the middle of the Gulf where numerical results suggest existence of eddies.