Thermal Budget of a Monsoon Depression in the Bay of Bengal during FGGE-MONEX 1979

Kshudiram Saha Maharani Bagh, New Delhi—ll0065, India

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Suranjana Saha Department Of Meteorology, University of Maryland, College Park, Maryland

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Abstract

The paper presents die results of a study of the thermal budget of a monsoon depression that developed over the Bay of Bengal during the period 3–8 July 1979. The complete thermodynamic energy equation is considered, to examine the possible role of the various terms and to evaluate the total diabatic heating. In the west-southwest quadrant of the monsoon depression where there is considerable rainfall, latent heat released by precipitation appears to account for about 80% of the total diabatic heating. This heating appears to be offset by cooling due to strong upward motion; however, the total diabatic beating over an area immediately to the north-northeast of the depression center appears to be negative, suggesting downward air motion and adiabatic warming. It is suggested that this warm sector to the north-northeast of the depression center, which is maintained by subsidence warming may serve as an effective tropospheric energy source for the monsoon depression.

Abstract

The paper presents die results of a study of the thermal budget of a monsoon depression that developed over the Bay of Bengal during the period 3–8 July 1979. The complete thermodynamic energy equation is considered, to examine the possible role of the various terms and to evaluate the total diabatic heating. In the west-southwest quadrant of the monsoon depression where there is considerable rainfall, latent heat released by precipitation appears to account for about 80% of the total diabatic heating. This heating appears to be offset by cooling due to strong upward motion; however, the total diabatic beating over an area immediately to the north-northeast of the depression center appears to be negative, suggesting downward air motion and adiabatic warming. It is suggested that this warm sector to the north-northeast of the depression center, which is maintained by subsidence warming may serve as an effective tropospheric energy source for the monsoon depression.

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