Spectral wave characteristics off Gangavaram, Bay of Bengal

Abstract

Spectral wave characteristics were studied based on waves measured for 1 year during 2010 off Gangavaram, Bay of Bengal. Maximum wave height of 5.2 m was observed on 19 May 2010 due to the influence of cyclonic storm LAILA. The wave spectrum was single-peaked during 57 % of the time and the double-peaked spectrum observed was mainly swell-dominated. Low-frequency waves (0.05–0.15 Hz) were predominantly from 150° to 180°, whereas high-frequency waves (>0.15 Hz) during November–January were mainly from 90° to 120°, and during July and August from 180° to 210°. Annual average significant wave height was similar to the value (1 m) observed in the eastern Arabian Sea.

Appendix: Definition of wave parameters used in the study

$$ {\text{Significant wave height }}\left( {H_{\text{s}} } \right) = 4 { }\sqrt {m_{o} } $$

(A1)

$$ {\text{Mean wave period }}(T_{{{\text{m}}_{02} }} ) = \sqrt {m_{0} /m_{2} } $$

(A2)

$$ {\text{Spectral narrowness parameter }}(\nu ) = \sqrt {\frac{{m_{0} \;m_{2} }}{{m_{1}^{2} }} - 1} $$

(A3)

$$ {\text{Spectral peakedness parameter (}}Q_{\text{p}} )= \frac{2}{{m_{0}^{2} }}\int\limits_{0}^{\infty } {fS^{2} (f)\;{\text{d}}f} $$

(A4)

where m _n is the nth order spectral moment and is given by,

$$ m_{n} = \int\limits_{0}^{\infty } {f^{n} S(f)\;{\text{d}}f,\quad n = 0,1,2{\text{ and }}4} $$

S(f) is the spectral energy density at frequency f.