Variability of Significant Wave Height over the Indian Ocean Using Empirical Orthogonal Function Analysis

Abstract

Spatial-temporal variability of significant wave height (SWH) over the Indian Ocean has been explored in the study. The SWH have been generated for the period 2000–08 using WAM-4C forced by six hourly QSCAT/NCEP blended winds. After a preliminary validation of the model generated SWH, the two dimensional fields of the same have been subjected to empirical orthogonal function (EOF) analysis. Analysis has been carried out separately in four regions, which are oceanographically distinct because of the prevailing wind regimes. These are namely Bay of Bengal (BOB), Arabian Sea (AS), equatorial and off-equatorial southern Indian Ocean (EOESIO) and Southern Indian Ocean (SIO). The first eigenmode accounts for 75%, 83%, 40% and 23% of the total variability for the BOB, AS, EOESIO and SIO respectively. In the BOB the maximum loading is in the northeast corner of the basin due to the predominant northeastward propagation of the waves due to the prevailing strong southwesterly monsoon winds, while in the AS there is an alignment of the maximum loading along the Findlater jet. As regards the other two regions, it can be inferred that there is a trend of increasing loading as one move gradually southwards due to the increase in the strength of the winds.