Fig. 3: Trends in genesis potential index (GPI) during the pre-monsoon season and the contributions of environmental factors.

a Trends in GPI during the pre-monsoon season (April–June) over the North Indian Ocean (NIO) basin from 1981 to 2023. Trends in GPI during the pre-monsoon season for varying (b) potential intensity (PI), (c) relative humidity (RH), (d) relative vorticity (RV), (e) vertical wind shear (VWS), and (f) vertical wind velocity (W) with other environmental factors as climatology. The black cross indicates the linear trend that is significant at the 95% confidence level. The base map was generated using geographic coordinate system World Geodetic System 1984 generated by Global Positioning System (maintained by the National Oceanic and Atmospheric Administration).