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Reduced near-surface thermal inversions in 2005-06 in the southeastern Arabian Sea (Lakshadweep Sea)

Nisha, K and Rao, SA and Gopalakrishna, VV and Rao, RR and Girishkumar, MS and Pankajakshan, T and Ravichandran, M and Rajesh, S and Girish, K and Johnson, Z and Anuradha, M and Gavaskar, SSM and Suneel, V and Krishna, SM (2009) Reduced near-surface thermal inversions in 2005-06 in the southeastern Arabian Sea (Lakshadweep Sea). Journal of Physical Oceanography, 39 (5). pp. 1184-1199.

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Repeat XBT transects made at near-fortnightly intervals in the Lakshadweep Sea (southeastern Arabian Sea) and ocean data assimilation products are examined to describe the year-to-year variability in the observed near-surface thermal inversions during the winter seasons of 2002-06. Despite the existence of a large low-salinity water intrusion into the Lakshadweep Sea, there was an unusually lower number of near-surface thermal inversions during the winter 2005/06 compared to the other winters. The possible causative mechanisms are examined. During the summer monsoon of 2005 and the following winter season, unusually heavy rainfall occurred over the southwestern Bay of Bengal and the Lakshadweep Sea compared to other years in the study. Furthermore, during the winter of 2005, both the East India Coastal Current and the Winter Monsoon Current were stronger compared to the other years, transporting larger quantities of low salinity waters from the Bay of Bengal into the Lakshadweep Sea where a relatively cooler near-surface thermal regime persisted owing to prolonged upwelling until November 2005. In addition, the observed local surface wind field was relatively stronger, and the net surface heat gain to the ocean was weaker over the Lakshadweep Sea during the postmonsoon season of 2005. Thus, in winter 2005/06, the combination of prolonged upwelling and stronger surface wind field resulting in anomalous net surface heat loss caused weaker secondary warming of the near-surface waters in the Lakshadweep Sea. This led to a weaker horizontal sea surface temperature (SST) gradient between the Lakshadweep Sea and the intruding Bay of Bengal waters and, hence, a reduced number of thermal inversions compared to other winters despite the presence of stronger vertical haline stratification.

Item Type: Article
Additional Information: Copyright of this article belongs to American Meteorological Society
Uncontrolled Keywords: Bay of Bengal; Coastal currents; Heat gains; Heavy rainfall; Lakshadweep sea; Local surfaces; Low-salinity water; Near-surface; Ocean data assimilation; Post-monsoon; Sea Surface Temperature gradients; Southeastern arabian seas; Summer monsoon; Surface heat loss; Surface wind fields; Thermal inversion; Thermal regimes; Winter monsoon; Winter seasons, Atmospheric temperature; Ocean engineering; Rain; Salinity measurement; Surface waters, Ocean currents, data assimilation; data inversion; sea surface salinity; sea surface temperature; temperature gradient; thermal regime; warming, Arabian Sea; Asia; Bay of Bengal; Eurasia; India; Indian Ocean; Indian Ocean islands; Lakshadweep; South Asia
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 22 Feb 2015 05:38
Last Modified: 22 Feb 2015 05:38

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