Geophysical Research Letters (Feb 2019)

On Moisture Flux of the Indian Summer Monsoon: A New Perspective

  • Kusuma G. Rao,
  • N. Narendra Reddy

DOI
https://doi.org/10.1029/2018gl080392
Journal volume & issue
Vol. 46, no. 3
pp. 1794 – 1804

Abstract

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Abstract Moisture flux is the driver of the Indian summer monsoon on all space‐time scales and its accurate representation in monsoon simulation models is crucial. For the first time, the moisture flux measurements are made over India during the PRWONAM (Prediction of Regional Weather using Observational meso‐Network and Atmospheric Modelling) program. These measurements best represented low wind free convection regime (U10 < 2 m/s). Here we show moisture flux scaled linearly with appropriate near‐surface humidity and temperature differentials. The drag scaled linearly with wind speed unlike the moisture and sensible heat fluxes. The sensible heat flux scaled as “4/3” power of a near‐surface temperature differential consistent with Rao et al. (1996a, https://doi.org/10.1029/96GL02368) and Rao (2004, https://doi.org/10.1023/B:BOUN.0000016495.85528.d7). A striking result is that the moisture flux is a linear function of the sensible heat flux at all wind speeds; while drag does not show any dependence on heat flux.

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