Summary of Abstract Submission

Abstract Submission No. IO50-05-0015PresentationOral


M K Roxy*1, K Ritika1, Pascal Terray2, Raghu Murtugudde3, Karumuri Ashok4, B N Goswami5

1 Indian Institute of Tropical Meteorology, India
2 Sorbonne Universites, France
3 University of Maryland, USA
4 University of Hyderabad, India
5 Indian Institute of Science Education and Research, India


There are large uncertainties looming over the status and fate of the South Asian summer monsoon, with several studies debating whether the monsoon is weakening or strengthening in a changing climate. Our analysis using multiple observed datasets demonstrates a significant weakening trend in summer rainfall during 1901-2012 over the South Asian subcontinent, extending from south of Pakistan through central India to Bangladesh, with up to 10-20% reduction over central-eastern India. Earlier studies have suggested an increase in moisture availability and land-sea thermal contrast in the tropics due anthropogenic warming, favoring an increase in tropical rainfall. In contrast, we notice a weakened land-sea thermal contrast due to rapid warming in the Indian Ocean, along with a relatively subdued warming over the subcontinent. Using long-term observations and coupled model experiments, we provide compelling evidence that the enhanced Indian Ocean warming weakens the land-sea thermal contrast, dampens the summer monsoon Hadley circulation, and thereby reduces the rainfall over South Asia.