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

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 - 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 (similar to73 degreesE) about 40 days after they occur near the coast in the eastern LS ( similar to 75.5 degreesE). 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.