SES organises a talk by Dr. Ramesh Yadav

Event From Date: 
Friday, 7 December 2018
Event End Date: 
Friday, 7 December 2018
Event Title: 
SES organises a talk by Dr. Ramesh Yadav
Event Details: 

School of Environmental Sciences

Jawaharlal Nehru University

 

Cordially invites you to a talk on

 

Atlantic Niño modulation of the Indian Summer Monsoon

 

Dr. Ramesh Yadav, IITM, Pune

 

7th December 2018 (Friday) 3:30pm

Amrita Devi Bishnoi Seminar Hall, SES.

 

Abstract: The Indian rainfall and the Atlantic Niño peaks during summer month and have inverse relationship. This relationship has been revisited and it is found that the Atlantic Niño significantly influences a dipole pattern of rainfall in the north–east and the north-western parts of India. The positive phase of the Atlantic Niño intensifies the inter-tropical convergence zone, owing to the enlargement of the upper-troposphere divergence and local tropospheric warming, over the equatorial east Atlantic and West Africa. This provokes meridional stationary wave owing to the stronger meridional transfer of energy, as the influences of background jet-streams are minimal over North Africa and Europe. This results in the consecutive anomalous negative, positive, and negative geopotential heights (GPHs) over the tropical east Atlantic, Mediterranean, and north–west Europe, respectively. The north–west Europe acts as the center of action for the propagation of a Rossby wave train zonally oriented toward central Asia reinforcing positive GPH anomaly over there. The positive GPH anomaly reduces the Asian subtropical westerly Jetstream east of the Caspian Sea, owing to the reduction in the upper-troposphere divergence toward the Indian subcontinent and caused for above (below) normal north–east (north–west) Indian summer monsoon rainfall. The atmospheric general circulation model captures general characteristics of wave pattern and changes in the Asian jet when correlated with Atlantic Niño with considerable skill.