On magnitudes of rapid intensification and destruction of tropical cyclones over the North Indian Ocean

Abstract

The study targets long‐term analysis of rapid intensification (RI) magnitudes and destructiveness of tropical cyclones (TCs), as well as factors that are responsible for those magnitudes over the North Indian Ocean (NIO). Out of 131 TCs during 1990–2021, 50 TCs (38%) exhibited RI in their lifetime. Results indicate that the lifetime maximum intensity (LMI) and landfall intensity (LFI), along with the potential destructive index (PDI), are directly proportional (correlation coefficient > 0.8) to the lifetime maximum intensification rate. Most RI TCs (~80%) made landfall with an average LMI, LFI and PDI of 95 knots, 85 knots and 4 × 107 knot3, respectively. And the destructive indices are more than double compared to landfalling non‐RI TCs. Recent years have witnessed an increasing trend in RI magnitude and the frequent occurrence of very RI cases (intensity change ≥50 knots in 24 h). It infers that recent TCs have achieved RI and higher magnitudes in a short duration (~20 h). The higher intensification rates are promoted by lower wind shear as well as strong surface latent and sensible heat fluxes. The higher sea surface temperature by ~0.2°C, oceanic heat content by ~60 × 107 J·m−2, lower tropospheric humidity by ~0.2 g·kg−1 and moist static energy by ~6 × 106 J·m−2 in the recent period (2007–2021) supports higher intensification rates as compared to the earlier period (1990–2006). The deep‐layer wind shear has decreased by 1.0 m·s−1 in recent years, which supports higher RI magnitudes. This study highlights the risk associated with RI magnitudes and the efforts to be made for improved predictions of higher intensification rates.