Analysis of tropical cyclones using climate networks: Cyclone Ockhi, a case studyNeelima Gupte, Vinisha Kalwani and Rupali SononeDepartment of Physics, Indian Institute of Technology, Madras, Chennai 600036. India.

We apply the methods of climate networks studies for the analysis of tropical cyclones. Here, we apply thse methods to a specific cyclone, Cyclone Okhi (29th Nov to 6th Dec. 2017). This cyclone was classified as a severe cyclone with wind speeds ranging from 150 to 175 kms per hour and caused substantial destruction. The cyclone is studied using a geographic grid of finite size based on the Indian Ocean and networks on time scales of 15 days. We study various quantities such as heat maps, distributions of teleconnections, betweenness centralities and area weighted connections which constitute signatures of cyclonic behaviour. The geographic locations of peak values of these quantities shift substantially before, during and after the cyclones, demonstrating their potential for predictive behaviour. The climate network undergoes abrupt percolation transitions during this period. The location of tipping links which trigger the abrupt transition is identified. Our methods and results can be generalised to other cyclones as well as other extreme events.