דוקטורנטים מספרים - Sohan Suresan

Merged Atlantic and African jets: From instanton theory to predictability of temperature and precipitation extremes

By Sohan Suresan

Supervisor: Prof. Nili Harnik

Hello! My name is Sohan Suresan. I am a PhD student from the Dept. of Geophysics at Tel Aviv University. I received my bachelor's and master's degrees in physics at the Indian Institute of Science Education and Research (IISER), Pune, India before moving to Israel for my PhD research.

My research focuses on understanding and predicting extreme dynamical events and specifically when the jet stream and storms in the North Atlantic behave in a very unusual way for a relatively long period. For example, uch a rare state of the flow occurred during the winter of 2009-10 when the usually separate Atlantic and African jets merged into one zonal jet. Such a situation is more typical of the Pacific jet stream, resulting in unusually cold and wet conditions in North America, Europe and even China. During my research I apply a novel rare event algorithm to produce an ensemble of model runs of similar winter flow conditions, to study both the dynamics of these events and their predictability using dynamical systems tools. This project aims to: (i) study the physical processes underlying rare merging events of the Atlantic and African jets; (ii) characterize precursors to the merging by analogy with instanton theory in statistical mechanics; and (iii) use the latter to improve our predictive capabilities for associated weather extremes, such as surface temperature and precipitation extremes.