Relating a Large‐Scale Variation of Waves in the Indian Ocean to the IOD

Abstract

AbstractThis study used the ERA‐5 40‐year reanalysis data set from the European Centre for Medium‐Range Weather Forecasts to analyze the spatial characteristics of wind waves and swells in the Indian Ocean. Although swells from the Southern Ocean can propagate into the Bay of Bengal, the zonal surface Stokes drift has been shown to correlate well with wind waves. Investigation of the relationship between the Indian Ocean Dipole (IOD) and the surface Stokes drift revealed strong correlation in the tropical Indian Ocean. The surface Stokes drift plays a positive role in maintaining sea surface temperature stability by transporting more (less) abnormally cold water during periods of positive (negative) IOD events. The depth‐integrated wave transport is quantified by the spectra and bulk parameters, respectively. Although two methods provide estimates of the same order of magnitude, the transport value is larger when wave spectra are used. With this approach, the estimated wave transport is comparable to the Ekman transport and its zonal component is even greater for more than 80% of the sea areas in the Indian Ocean; thus, it would have substantial effect on sea surface temperature. This paper proposes a new idea for studying this climatic phenomenon by considering the large‐scale wave effect, which builds a bridge for energy transport between the eastern and western boundaries of the Indian Ocean.