Abstract
Abstract. An understanding of the wave spectral shapes is of primary importance for the design of marine facilities. In this paper, the wave spectra collected from January 2011 to December 2015 in the coastal waters of the eastern Arabian Sea using the moored directional waverider buoy are examined to determine the temporal variations in the wave spectral shape. Over an annual cycle for 31.15 % of the time, the peak frequency is between 0.08 and 0.10 Hz; the significant wave height is also relatively high (∼ 1.55 m) for waves in this class. The slope of the high-frequency tail of the monthly average wave spectra is high during the Indian summer monsoon period (June–September) compared to other months, and it increases with an increase in significant wave height. There is not much interannual variation in the slope for swell-dominated spectra during the monsoon, while in the non-monsoon period when wind-seas have a high level of influence, the slope varies significantly. Since the exponent of the high-frequency part of the wave spectrum is within the range of −4 to −3 during the monsoon period, the Donelan spectrum shows a better fit for the high-frequency part of the wave spectra in monsoon months compared to other months.
Highlights
Information on wave spectral shapes is required for designing marine structures (Chakrabarti, 2005), and almost all of the wave parameter computations are based on the wave spectral function (Yuan and Huang, 2012)
This study addresses two main issues: (1) how the high-frequency tail of the wave spectrum varies in different months and (2) the spectral parameters for the best-fit theoretical spectra
Since the exponent of the high-frequency tail of the wave spectrum is within the range of −4 to −3 during the monsoon period, the Donelan spectrum shows a better fit for the monsoon spectra compared to other months (Fig. 11)
Summary
Information on wave spectral shapes is required for designing marine structures (Chakrabarti, 2005), and almost all of the wave parameter computations are based on the wave spectral function (Yuan and Huang, 2012). Wind and wave data measured at a few locations along the western coast of India for a short period of 1 to 2 months as well as the wave model results were analyzed to study the wave characteristics in the deep and nearshore regions during different seasons (Vethamony et al, 2013). Amrutha et al (2017) analyzed the measured wave data in October and reported that the high waves (significant wave height > 4 m) generated in an area bounded by 40–60◦ S and 20–40◦ E in the southern Indian Ocean reached the eastern AS in 5–6 days and resulted in the long-period waves. We used the directional waverider buoy with measured wave spectral data at 15 m of water depth off Karwar on the western coast of India over 5 years from 2011 to 2015 and evaluated the nearshore wave spectral shapes in different months.
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