Observed mini‐cold pool off the southern tip of India and its intrusion into the south central Bay of Bengal during summer monsoon season

Abstract

[1] The observed mini-cold pool (MCP) off the southern tip of India (STI) and its intrusion into the south central Bay of Bengal (BoB) during the summer monsoon season is examined utilizing the available satellite and in situ measurements. The mechanisms that govern the occurrence of this MCP through surface wind field and its curl, net surface heat flux and divergence in the near-surface circulation (Ekman + geostrophic) are examined. The observed MCP primarily appears to be driven by the upwelling caused by the divergence in the near-surface circulation. The upwelling results in both shoaling of thermocline and enhanced blooming of chlorophyll-a. With the progress of the season the sea surface temperature (SST) cooling associated with MCP intrudes into the south central BoB by the Summer Monsoon Current (SMC).

Observed intraseasonal variability of mini‐cold pool off the southern tip of India and its intrusion into the south central Bay of Bengal during summer monsoon season

“…In addition, a suggestion of advection of cooler waters from the western AS into this region is also seen. Rao et al [2006] have suggested that the observed MCP primarily appears to be driven by the upwelling caused by the divergence (Ekman + geostrophic) in the near-surface circulation. The divergence of the nearsurface circulation also shows maxima off the STI extending into the south central BoB around Sri Lanka resembling the concave shape of cool SSTs (Figure 1b).…”

“…[2] During the summer monsoon season a MCP occurs south of the STI due to intense surface cooling in response to the upwelling driven by the divergence in the nearsurface circulation [Rao et al, 2006]. During this season the SMC also carries cool and high saline waters from the Arabian Sea (AS) into the south central BoB [Vinayachandran et al, 1999;Jensen, 2001].…”

A new atlas of temperature and salinity for the North Indian Ocean

“…The cold pool starts strengthening from June, and reaches its peak in August. The cold pool (Joseph et al 2005), which is a result of the eastward advection of the cold waters into the southern bay Rao et al 2006aRao et al , 2006b), did not extend as far east as in WOA09.…”

Hydrography and Circulation in the Eastern Tropical Indian Ocean during April-May 2011

“…In winter, low-salinity water from the northern BOB is transported southward along the East Indian coast, toward the Arabian Sea via the Sri Lanka coastal area (Schott and McCreary, 2001). Similar processes operate, though in an opposite direction, in summer (Murty et al, 1992;Rao et al, 2006). Another important current is the Wyrtki Jet located between 2°S and 2°N in the equatorial Indian Ocean, which is an intensive and narrow eastward surface current that occurs twice a year during the monsoon transition periods in spring (April-May) and fall (October-November, Wyrtki, 1973).…”

“…The jets advect the Arabian Sea's salty water eastward along the equator and thereby change the upper ocean salt budgets in the eastern Indian Ocean (Masson et al, 2004). Several observational studies have been conducted to address the hydrographic distributions and the associated circulation in the ETIO for the two monsoon periods and the boreal fall transition period (Suryanarayana et al, 1993;Eigenheer and Quadfasel, et al, 2000;Rao et al, 2006). The seasonal and interannual variability in circulation and its mechanism of formation in the ETIO have been previously studied using numerical models (Hacker et al, 1998;Jensen, 2001).…”