Island wake circulation off Maldives during boreal winter, as visualised with MODIS derived chlorophyll‐a data and other satellite measurements

Abstract

The north equatorial current (NEC) is a seasonal current that exhibits variability in its strength and transport. In this paper, the westward flow of the NEC in the Indian Ocean has been observed during the northeast monsoon. The NEC passes through the Maldives, a group of coral islands in the central part of the equatorial Indian Ocean along 73° E. This flow has been shown to enhance biological productivity on the west coast of the Maldives during boreal winter. This was visualized with chlorophyll‐a data derived using a Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on 11 December 2003. The plumes of chlorophyll‐a showing the progress of the westward flow through the Kardive channel on the west coast of the Maldives during the winter of 2003 to 2004 were studied. Analysis of weekly chlorophyll‐a data from November to March 2000 to 2004 also indicated westward flow with distinct inter‐annual and intra‐season variations. The surface wind, obtained from Quicksat scatterometer data, and the mean sea level anomaly, obtained from altimeter data corresponding to the flow were also analysed. Hydrographic observations studied with ARGO floats around the area also provided supporting evidence of the flow through the Maldives group of islands in the Indian Ocean.