Evaluation of track length, residence time and translational speed for tropical cyclones in the North Indian ocean

The present study performed a critical examination on the historical tracks of 185 tropical cyclonic events that developed over North Indian Ocean basin during the past 37 years (1982–2018). Analysis of cyclone tracks was carried out including all categories starting from Deep Depression (DD) to Super Cyclonic Storm (SuCS) stages. Results from the study indicate that the track length have decreased by about 13%, whereas the residence time increased by 7.3% for all categories considered during the study period. However, the high-intense cyclone categories showed an increase in both track lengths and residence time that was statistically significant. The net increase was about 10% and 43% for the track lengths and residence time, respectively. Segmented analysis clearly brings out the significant upward trend in track length and residence time during the recent decade (2009–2018). Further, the study examined the variability in translational speed on annual and inter-seasonal scales for cyclonic disturbances that formed over the Bay of Bengal basin. The overall trend is showing a decreasing pattern with a net reduction of 2.5 km/h over the past three decades. A detailed assessment was carried out to understand the trends in these parameters for the North Indian Ocean region. The study has practical implications in better understanding the characteristics of tropical cyclones and coastal vulnerability.