Coastal upwelling along the southwest coast of India – ENSO modulation

Abstract

An index of El Niño Southern Oscillation (ENSO) in the Pacific during pre monsoon season is shown to account for a significant part of the variability of coastal Sea Surface Temperature (SST) anomalies measured a few months later within the wind driven southwest coast of India coastal upwelling region 7 • N-14 • N. This teleconnection is thought to result from an atmospheric bridge between the Pacific and north Indian Oceans, leading to warm (cold) ENSO events being associated with relaxation (intensification) of the Indian trade winds and of the wind-induced coastal upwelling. This ENSO related modulation of the wind-driven coastal upwelling appears to contribute to the connection observed at the basin-scale between ENSO and SST in the Arabian Sea. The ability to use this teleconnection to give warning of large changes in the southwest coast of India coastal upwelling few months in advance is successfully tested using data from 1998 and 1999 ENSO events.

Macrobenthic Community Structure Response to Coastal Hypoxia off Southeastern Arabian Sea

“…The nutrient rich in upwelled water causes oxygen shortage in the subsurface water along the SEAS during SM. The observed high DO values on the normoxia zone and low DO values in the hypoxic zone were in agreement with earlier studies of the west coast of India (Muni Krishna 2008). The lowest DO value ranged from 0.04-0.8 ml.L -1 SM, whereas high DO values (4.38-5.5 ml.L -1 ) observed along the normoxia conditions SIM and high tolerance in low oxygen levels has moderately connected with continuously low temperature and oxygen deficiency apt to promoted with decreasing temperature [34][35][36].…”

“…During the southwest monsoon the southward movement of the West Indian coastal current influences the upwelling and it causes the hypoxia condition in the Arabian Sea [13]. During southwest monsoon the coastal upwelling occurs along west coast of India between 7°N and 14°N [14][15][16].…”

High Incidence of Lysogeny in the Oxygen Minimum Zones of the Arabian Sea (Southwest Coast of India)

“…The temperature also showed the upsloping of isotherms towards the coastal region under the influence of strong Ekman pumping. Intense upwelling which occurs along the western coast of India during the southwest monsoon season [ 45 , 46 ] advances progressively from south to north [ 47 , 48 ]. It brings in the nutrient-rich subsurface waters to the surface to enhance the surface productivity and subsequently leads to increased particulate flux at greater depths.…”

Retracted: ENSO‐related modulation of coastal upwelling along the central east coast of India

“…The central east coast of India (CEI) is a monsoon‐dominated coast. Coastal upwelling occurs along the coast during the winter monsoon (JF) and transition period (MA) between 20°N and 13°N (LaFond, 1954, 1957, 1958; Rao, 1956; Varadachari, 1958, 1961; LaFond and LaFond, 1968; Murthy and Varadachari, 1968; Rao et al , 1986; Rao and Rao, 1989; Naidu et al , 1999; Rao, 2002; Muni Krishna, 2007). In this region, upwelling is a wind‐driven process and the strength of alongshore winds stress modulates the coastal divergence and hence the input of cold‐upwelled water over the shelf.…”