Atlantic zonal mode-monsoon teleconnection in a warming scenario

C. T. Sabeerali, R. S. Ajayamohan, V. Praveen

Research output: Contribution to journalArticlepeer-review

Abstract

The dominant interannual SST variability in the eastern equatorial Atlantic is referred to as the Atlantic Zonal Mode (AZM), which peaks in boreal summer impacts global weather patterns. The cold (warm) phase of this ocean-atmospheric coupled phenomenon enhances (weakens) the intensity of the Indian Summer Monsoon Rainfall (ISMR). Observational studies show a strengthening relationship between AZM and ISMR in recent decades, providing a predictive signal for the ISMR. However, a suite of Coupled Model Intercomparison Project Phase 6 (CMIP6) model simulations in the highest emission scenario (SSP58.5) show a weakening relationship between ISMR and AZM in the future (2050–2099). The strengthening of atmospheric thermal stability over the tropical Atlantic in the warming scenario weakens the associated convection over the eastern equatorial Atlantic in response to the warm phase of AZM. This leads to weakening velocity potential response over the Indian subcontinent, resulting in a weak AZM–ISMR relationship. There is no convincing evidence to indicate that either the tropical Atlantic SST bias or the AZM–ISMR teleconnection bias plays a crucial role in the potential weakening of this relationship. These results imply that ISMR prediction will become more challenging in a warming scenario as one of the major external boundary forces that influence monsoon weakens.

Original languageEnglish (US)
JournalClimate Dynamics
DOIs
StateAccepted/In press - 2021

Keywords

  • Atlantic Zonal Mode
  • AZM-Monsoon Teleconnection
  • CMIP6 models
  • Global warming
  • Indian summer monsoon

ASJC Scopus subject areas

  • Atmospheric Science

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