High Frequency Tail Characteristics in the Coastal Waters off Gopalpur, Northwest Bay of Bengal: A Nearshore Modelling Study
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Over the years, continued uncertainty amid − 4 and − 5 frequency exponent representation observed in the slope of the high-frequency tail of a wind-wave frequency spectrum is a major concern. To comprehend the nature of the high-frequency tail an effort has been made to assess the slope of the high-frequency tail with measured data recorded for 3 years off Gopalpur. The study demonstrates that the high-frequency slope of the spectra varied seasonally in the range of n = − 2.13 to − 3.48. The swell and wind sea parameters calculated by separation frequency method, shows that 64.6% of waves were dominant by swell and the rest 34.9% by sea annually. Single, double and multi-peaked spectra occur 12.23, 71.80 and 15.37% annually. To simulate wave spectra, the nested WAM-SWAN model is forced with ERA-Interim winds and 1D wave spectra comparisons, when performed, proved to be encouraging. From the comparisons of measured and theoretical spectra it is concluded that JONSWAP model could not describe the high-frequency tail of measured spectrum, as indicated by the very high Scatter Index ranging from 0.24 to 1.44. Whether there exists a correct slope for the high-frequency tail is still a question. Moreover, the philosophy of a unique slope at any coastal location remains uncertain for the wave modelling community.
KeywordsShallow water waves Wave spectrum high-frequency tail WAM-SWAN validation JONSWAP Gopalpur coastal spectra
The authors would like to thank the Director, ESSO-INCOIS, Hyderabad under the Ministry of Earth Sciences, Government of India for the support and encouragement. The efforts made for wave rider buoy data collection by the team including Mr. Arun N, Mr. Jeyakumar, and Mr. Rameshkumar of ESSO-INCOIS is thankfully acknowledged. We would also like to thank the anonymous reviewers for their valuable suggestions for improving the manuscript.
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