A229-0014
Impact of the Himalayan-Tibetan Highland Orography on Somali Jet and Tropical Easterly Jet and the Indian Summer Monsoon

Wednesday, 16 December 2020
Poster
Popat Salunke, Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi, India, Saroj K. Mishra, Centre for Atmospheric Sciences, Indian Institute of Technology, New Delhi, India and Abhishek Anand, DST Centre of Excellence in Climate Modeling, Indian Institute of Technology Delhi, New Delhi, India
Abstract:
The impact of the Himalayan-Tibetan Highlands (HTH) in the Somali jet (SJ) and tropical easterly jet (TEJ) is investigated through numerical simulations. For this study, a set of two simulations is carried out using the Community Atmosphere Model (CAM5.1), the first one is the Control simulation (CTL), the second one is the simulations by removing orography over HTH. The investigation of the first set of experiments reveals that the TEJ intensity is well correlated with the Indian summer monsoon (ISM) rainfall. This study shows that without HTH orography, precipitation is significantly reduced (4–12 mm day−1) over the Indian region due to the reduction in the magnitude of SJ (5–7 m s-1) and TEJ (4 –8 m s-1) in comparison to CTL simulation. It also noted that the removal of orography gives negative feedback to the monsoonal system by reducing the land-ocean temperature gradient, which weakens monsoon. The numerical simulations results indicate that mountains also play a crucial role in determining the strength of the SJ, TEJ, and the seasonal evolution of ISM. Overall the result suggests that removing the HTH orography reduces precipitation, TEJ, and SJ winds circulation over the ISM regions.

Key Words: Somali Jet, Tropical Easterly Jet, Indian Summer Monsoon, CAM5.1

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