Role of the Indian Ocean in the ENSO-Indian summer monsoon teleconnection in the NCEP climate forecast system

Deepthi Achuthavarier, V. Krishnamurthy, Ben P. Kirtman, Bohua Huang

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

The observed negative correlation between El Niño-Southern Oscillation (ENSO) and the Indian summer monsoon is not simulated by the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS) coupled model. The correlation is partially restored in the simulations where the Indian Ocean (IO) sea surface temperature (SST) is prescribed with the daily mean or climatology. Comparison among the simulations suggests that ENSO-induced SST anomalies form a strong dipole pattern oriented along the zonal direction in the IO in the coupled model, preventing the ENSO signals from reaching the Indian monsoon region. In the model, the dipole develops early in the monsoon season and extends to the central equatorial IO while it is formed at the end of the season in observations. The dipole modifies low-level winds and surface pressure, and grows in a positive feedback loop involving winds, surface pressure, and SST. Examination of themean state in themodel reveals that the thermocline is relatively shallow in the eastern IO. This preconditions the ocean such that the atmospheric fluxes can easily impart fluctuations in the subsurface temperature and thereby in the SST. These results suggest that biases in the IO can adversely affect the ENSO-monsoon teleconnection in a coupled model.

Original languageEnglish (US)
Pages (from-to)2490-2508
Number of pages19
JournalJournal of Climate
Volume25
Issue number7
DOIs
StatePublished - Apr 1 2012

Keywords

  • Atmosphere-ocean interaction
  • Coupled models
  • ENSO
  • Interannual variability

ASJC Scopus subject areas

  • Atmospheric Science

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