Researchers project changes in monsoon activity over the next century. Low-pressure systems (LPS) are cyclonic atmospheric vortices found in monsoon regions. Previous studies suggest that LPS activity has decreased since the mid-20th century, but how LPS activity will change under future warming remains unclear. R.S. Ajayamohan and colleagues used monthly sea surface temperatures to model past and future LPS activity in India, where LPS are prominent and produce more than half of the region's precipitation. Using a high-resolution atmospheric model, the authors simulated LPS activity for the period from 1981 to 2005 and during the late 21st century, from 2071 to 2095. In a business-as-usual emissions scenario, the authors found that Indian monsoon LPS activity declined by around 45% by the late 21st century. Additionally, the authors observed a poleward shift in the geographic distribution of LPS formation that was associated with approximately 60% decrease in oceanic LPS formation and approximately 10% increase in LPS formation over land in the region, resulting in an increase of extreme precipitation in northern India. A statistical model linked the weakening and poleward shift of LPS formation to large-scale weakening and poleward shift in monsoon vorticity, or potential energy, in the region. According to the authors, the findings carry implications for uncovering future changes to the hydrological cycle in the region.
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Article #17-09031: "Decline and poleward shift in Indian summer monsoon synoptic activity in a warming climate," by S. Sandeep, R. S. Ajayamohan, William R. Boos, T. P. Sabin, and V. Praveen.
MEDIA CONTACT: R. S. Ajayamohan, New York University Abu Dhabi, UNITED ARAB EMIRATES; tel: +97126285014, +971566129829; e-mail: Ajaya.Mohan@nyu.edu
Journal
Proceedings of the National Academy of Sciences