• DOI:10.1175/JCLI3820.1
• Corpus ID: 10435613

Weakening of North Indian SST Gradients and the Monsoon Rainfall in India and the Sahel

@article{Chung2006WeakeningON,
  title={Weakening of North Indian SST Gradients and the Monsoon Rainfall in India and the Sahel},
  author={Chul E. Chung and Veerabhadran Ramanathan},
  journal={Journal of Climate},
  year={2006},
  volume={19},
  pages={2036-2045}
}

• C. Chung, V. Ramanathan
• Published 15 May 2006
• Environmental Science
• Journal of Climate

Abstract Sea surface temperatures (SSTs) in the equatorial Indian Ocean have warmed by about 0.6–0.8 K since the 1950s, accompanied by very little warming or even a slight cooling trend over the northern Indian Ocean (NIO). It is reported that this differential trend has resulted in a substantial weakening of the meridional SST gradient from the equatorial region to the South Asian coast during summer, to the extent that the gradient has nearly vanished recently. Based on simulations with the Community Climate Model Version 3 (CCM3), it is shown that the summertime weakening in the SST gradient weakens the monsoon circulation, resulting in less monsoon rainfall over India and excess rainfall in sub-Saharan Africa. The observed trend in SST is decomposed into a hypothetical uniform warming and a reduction in the meridional gradient. The uniform warming of the tropical Indian Ocean in the authors’ simulations increases the Indian summer monsoon rainfall by 1–2 mm day−1, which is opposed by a larger drying t...