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Observed Warming of Sea Surface Temperature in Response to Tropical Cyclone Thane in the Bay of Bengal


Affiliations
1 National Institute of Ocean Technology, Pallikaranai P.O., Chennai 600 100, India
2 Anna University, Guindy Campus, Chennai 600 025, India
3 International CLIVAR Monsoon Project Office, Indian Institute of Tropical Meteorology, Pashan Road, Pune 411 008, India
4 National Centre for Antarctic and Ocean Research, Headland Sada, Vasco-da-Gamma, Goa 403 804, India
 

An unusual near-surface warming was seen in observations from a moored buoy BD11 at 14°N/83°E, and a nearby Argo profiling float in the Bay of Bengal, during the passage of tropical cyclone Thane, during 25–31 December 2011. The cyclone induced a warming of sea surface temperature (SST) by 0.6°C to the right of the track. Heat budget analysis based on moored observations and satellite data rules out the role of horizontal advection and net heat flux in warming the surface layer. We find that vertical mixing/entrainment in response to the cyclone, in conjunction with a pre-storm temperature inversion (subsurface ocean warmer than SST) led to the observed warming. Pre-storm and post-storm salinity and temperature profiles from an Argo float close to the mooring BD11 have higher vertical resolution than the moored data; they suggest vertical mixing of the upper 70 m of the water column. The moored observations show that the thermal inversion, erased by storm-induced mixing, reappears in a few days.

Keywords

Bay of Bengal, Cyclone, OMNI Buoy, SST.
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  • Observed Warming of Sea Surface Temperature in Response to Tropical Cyclone Thane in the Bay of Bengal

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Authors

Simi Mathew
National Institute of Ocean Technology, Pallikaranai P.O., Chennai 600 100, India
Usha Natesan
Anna University, Guindy Campus, Chennai 600 025, India
G. Latha
National Institute of Ocean Technology, Pallikaranai P.O., Chennai 600 100, India
R. Venkatesan
National Institute of Ocean Technology, Pallikaranai P.O., Chennai 600 100, India
Rokkam R. Rao
International CLIVAR Monsoon Project Office, Indian Institute of Tropical Meteorology, Pashan Road, Pune 411 008, India
M. Ravichandran
National Centre for Antarctic and Ocean Research, Headland Sada, Vasco-da-Gamma, Goa 403 804, India

Abstract


An unusual near-surface warming was seen in observations from a moored buoy BD11 at 14°N/83°E, and a nearby Argo profiling float in the Bay of Bengal, during the passage of tropical cyclone Thane, during 25–31 December 2011. The cyclone induced a warming of sea surface temperature (SST) by 0.6°C to the right of the track. Heat budget analysis based on moored observations and satellite data rules out the role of horizontal advection and net heat flux in warming the surface layer. We find that vertical mixing/entrainment in response to the cyclone, in conjunction with a pre-storm temperature inversion (subsurface ocean warmer than SST) led to the observed warming. Pre-storm and post-storm salinity and temperature profiles from an Argo float close to the mooring BD11 have higher vertical resolution than the moored data; they suggest vertical mixing of the upper 70 m of the water column. The moored observations show that the thermal inversion, erased by storm-induced mixing, reappears in a few days.

Keywords


Bay of Bengal, Cyclone, OMNI Buoy, SST.

References





DOI: https://doi.org/10.18520/cs%2Fv114%2Fi07%2F1407-1413