01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-05-0133 |
| Title of Abstract | Increase in the intense cyclones in the Arabian Sea during the last decade and its reasons and characteristics |
| Authors | DR. R. HARIKUMAR*, Zahid G.G. |
| Organisation | INCOIS |
| Address | SCIENTIST - E, INCOIS, HYD HYDERABAD, TELENGANA, India Pincode: 500090 E-mail: harikumar@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | In the present study, decadal variability of the North Indian Ocean (NIO) cyclone characteristics and the reasons led to it are unraveled. Importantly, during the recent decade (2014⿿2023), the frequency of intense TCs over the Arabian Sea has increased remarkably compared to the previous decade (2004⿿2013), while such an increase is not seen in the BOB. In the NIO, positive anomaly of air temperature (~1°C) and specific humidity (~1 g kg-1), and an increase in the sea surface temperature anomaly (SSTA) of ~0.55°C during the last four decades were observed. The AS (BOB) shows stronger (weaker) subsurface warming throughout the 0⿿150m (100 m) layer, with anomalies surpassing 0.4°C (>0.1°C). In the recent decade, very high positive moisture loading (ML), low vertical wind shear, high positive vorticity, and strong positive anomaly (2-8 x1010 KJ cm-2) in the ocean heat content (OHC) were observed in the NIO. Such decadal variabilities are more visible in the AS than BOB. An important result from the present study is that the AS showed a substantial increase in δGPI (genesis potential index) of ~ 13-fold during the recent decade, largely driven by changes in the relative humidity. In contrast, the Bay of Bengal showed only a minor increase in it over the same period. Variability studies on GPI, SST, mid-level moisture, and wind shear reveals that the conduciveness for TC genesis and intensification has an increasing trend over the last four decades, notably in the last decade. By considering ESCS Tauktae as a typical TC case, a methodology was coined based on linear and multiple regression analyses, and quantified the prevalent role of ocean and/or atmosphere on the genesis and intensification which was continued as a knowledge gap for long. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Decadal variability, Tropical Cyclones, Northern Indian Ocean, Genesis Potential Index, ENSO, Arabian Sea |
| For Awards | no |