Storm surge studies in the North Indian Ocean: A review

Abstract

Warm tropical North Indian Ocean (NIO), like the warm tropical North Atlantic and South and Northeast Pacific oceans, is a breeding ground for tropical cyclones. Tropical cyclones occur, quite often with severe intensity, in the tropical NIO during pre-monsoon and post-monsoon seasons, and are accompanied by very strong winds, torrential rains and storm surges. A storm surge is a meteorologically forced long wave motion, which can generate sustained elevations of the sea surface above the levels caused by the normal astronomical tides. Although storm surges result

from the combined action of extreme wind stress and, to a lesser extent, reduced atmospheric pressure on shallow coastal shelf seas, the precise impact of the surge at any particular location is sensitive to certain meteorological, topographic and hydrological parameters, which include i) intensity and path of the cyclone and its spatial and temporal scales, ii) width and slope of the continental shelf, iii) geometry of local coastal and shelf features (bays, headlands, inlets, barrier islands, offshore islands and reefs), and iv) interactions of surge, astronomical tides, wind waves, river

discharge and precipitation. The havoc caused by storm surges is found to be extremely severe in many countries situated around the NIO rim. Hence, real time monitoring and prediction of storm surges is of great importance in these

regions. Various storm surge studies so far have taken place in the NIO region, particularly those in the Bay of Bengal and Arabian Sea, are dealt with in this article. After providing the details of the equations governing storm surges, an

up-to-date review is attempted. Eventually, the authors’ views on what future directions could be taken in order to improve numerical storm surge modeling and predictions in the NIO region are mentioned.