Impact of leading Indo-Pacific climatic modes in modulating the wave power variability and their trends in the North Indian Ocean

Abstract

The present study analyses the trend and variability in wave parameters (wave height and wave period) and wave power (WP) in the North Indian Ocean (NIO). The impact of climatic modes such as El-Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on the WP of NIO has been investigated using the European Centre for Medium-Range Weather Forecasts reanalysis datasets (ERA5) for the period 1959–2021. It is observed that along the west coast of India (WCI), the coastal WP increased from south to north during summer whereas, in winter and other seasons the WP increased from north to south. Instead, along the east coast of India (ECI), WP is higher on the north than the south, always. The annual WP climatology along the Indian coasts reveals that WP potential is higher along/adjacent to WCI than the ECI. It was observed that the total significant wave height (SWH) WP anomalies during normal and positive IOD (pIOD) events are mainly dominated by swell WP, whereas during El Niño and combined ENSO-IOD events, dominated by wind seas. During the peak of pure El-Niño, the SWH WP shows a basin-wide increase in WP anomalies. However, during summer, SWH WP showed increasing trends over Bay of Bengal. It is evident from the composite analysis that annual averaged WP anomalies are decreasing in normal, pure pIOD and combined events, but El-Niño is found to increase the WP anomalies over the Arabian Sea in the region north of 20°N. The present study advocates that a detailed analysis of WP along the Indian coastal regions is beneficial to the renewable energy industries to utilize this as an important energy resource.