Summary of Abstract Submission

Abstract Submission No. IO50-05-0015PresentationOral

WARM INDIAN OCEAN, WEAK ASIAN MONSOON

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

ABSTRACT :

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.