Observational evidence for westward propagation of temperature inversions in the southeastern Arabian Sea

Abstract

A warm pool forms in the southeastern Arabian Sea (SEAS) prior to the onset of the summer monsoon over India in early June; the core of this warm pool is in the Lakshadweep Sea (LS). XBT and surface salinity data collected in the LS during May 2002 to April 2003 show that temperature inversions occur off the southwest coast of India in early December with the arrival of low-salinity waters from the Bay of Bengal. The low-salinity waters and the inversions propagate westward along with the downwelling Rossby waves that constitute the Lakshadweep sea-level high; inversions occur in the western LS (~ 73 deg E) about 40 days after they occur near the coast in the eastern LS (~ 75.5 deg E). They disappear in April, when the Tropical Convergence Zone moves over the SEAS and the warm pool engulfs the region. Ocean dynamics and air-sea fluxes are together responsible for the formation and westward propagation of the inversions.