WAVE GROWTH UNDER VARIABLE WIND CONDITIONS

Marta Alomar, Rodolfo Bolaños- Sánchez, Agustín Sanchez-Arcilla, Abdel Sairouni

Abstract


Parametric wave growth curves are commonly used to empirically calculate wave height under fetch limited conditions and to tune the source functions of spectral wave models. There is not a unique wave growth function and many deviations from the first similarity laws have been reported. The applicability of the commonly used functions in variable wind conditions is expected to be limited. In this study we calculated wave growth curves with data from an instrumental set-up in the north-western Mediterranean. This region is characterized by non-homogeneous wind conditions (both in time and space). The first growth functions we calculated from the observations suggested higher wave growth rates than previously described by other authors. A close look to the sources of discrepancy in the calculations under such wind conditions revealed the importance to accurately separate sea from swell and to use only locally generated sea. The source of the wind data used for the scaling law is thought to be responsible for the remaining discrepancies from the commonly used growth functions. Wind and wave data from a high resolution simulation were used to calculate the growth functions from a spectral wave model, and to explore the importance of using in-situ wind measures to scale the variables. Simulated wave growth rates are lower than observed and lower than previously reported by other authors. Wind measurements from the most offshore buoy seem to be representative enough of the winds over the entire area. The results support the applicability of the well-known functions in the region of interest when certain conditions are met; i.e. pure wind sea conditions, and choosing a representative wind speed to scale the variables.

Keywords


variable winds; wave growth; fetch-limited; wave model; SWAN

References


Alomar, M., R. Bolaños, A. Sanchez-Arcilla, A. Sairouni, and F. Ocampo-Torres. 2009. Uncertainties in wave modeling for fetch-limited growth conditions. 33rd IAHR Congress: Water engineering for a sustainable environment, Vancouver, Canada, 2846-2853.

F. Ardhuin, T. H. C. Herbers, G. P. van Vledder, K. P. Watts, R. Jensen, and H. C. Graber. 2007. Swell and Slanting-Fetch Effects on Wind Wave Growth. Journal of Physical Oceanography, 37 (4), 908-931. http://dx.doi.org/10.1175/JPO3039.1

R. Bolaños, G. Jorda, J. Cateura, J. Lopez, J. Puigdefabregas, J. Gomez, and M. Espino. 2009. The XIOM: 20 years of a regional coastal observatory in the Spanish Catalan coast. Journal of Marine Systems, 77 (3), 237-260. http://dx.doi.org/10.1016/j.jmarsys.2007.12.018

M. Bottema, and G. P. van Vledder. 2009. A ten-year data set for fetch- and depth-limited wave growth. Coastal Engineering, 56 (7), 703-725. http://dx.doi.org/10.1016/j.coastaleng.2009.01.012

Cateura, J., A. Sánchez-Arcilla, and R. Bolaños. 2004. Wind climate at the Ebro delta and its relation with the sea state – clima de viento en el delta del ebro. Relación con el estado del mar. El clima, entre el mar y la montaña : IV Congreso de la Asociación Española de Climatología.

F. Dobson, W. Perrie, and B. Toulany. 1989. On the deep-water fetch laws for wind-generated surface gravity waves. Atmosphere-Ocean, 27 (1), 210-236. http://dx.doi.org/10.1080/07055900.1989.9649334

M. A. Donelan, J. Hamilton, and W. H. Hui. 1985. Directional Spectra of Wind-Generated Waves. Philosophical Transactions of the Royal Society of London.Series A, Mathematical and Physical Sciences, 315 (1534), 509-562. http://dx.doi.org/10.1098/rsta.1985.0054

W. M. Drennan, H. C. Graber, D. Hauser, and C. Quentin. 2003. On the wave age dependence of wind stress over pure wind seas. Journal of Geophysical Research, 108 .

K. Hasselmann, T. P. Barnett, E. Bouws, D. E. Carlson, D. E. Cartwright, K. Enke, J. A. Ewing, H. Gienapp, D. E. Hasselmann, P. Kruseman, A. Meerburg, P. Müller, D. J. Olbers, K. Richter, W. Sell, and H. Walden. 1973. Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP). Deutsche Hydrographische Zeitschrift, 8 (12), 1-95.

P. A. Hwang. 2008. Observations of swell influence on ocean surface roughness. Journal of Geophysical Research, 113 C12024. http://dx.doi.org/10.1029/2008JC005075

P. A. Hwang, and D. W. Wang. 2004. Field measurements of duration-limited growth of windgenerated ocean surface waves at young stage of development. Journal of Physical Oceanography, 2316-2326. K. K. Kahma. 1981. A study of the growth of the wave spectrum with fetch. Journal of Physical Oceanography, 1503-1515. K. K. Kahma, and C. J. Calkoen. 1992. Reconciling discrepancies in the observed growth of windgenerated waves. Journal of Physical Oceanography, 1389-1405.

S. A. Kitaigorodskii. 1962. Applications of the theory of similarity to the analysis of wind-generated wave motion as a stochastic process. Bulletin Academy of Sciences, USSR Geophysics Series, (1), 105-107.

Komen, G. J., Cavaleri, L., Donelan, M., Hasselmann, K., Hasselmann, S., and Janssen, P. A. E. M. (1994). Dynamics and modelling of ocean waves. Cambridge University Press, Cambridge, UK. http://dx.doi.org/10.1017/CBO9780511628955

PMid:7889022

G. J. Komen, K. Hasselmann, and K. Hasselmann. 1984. On the existence of a fully developed windsea spectrum. Journal of Physical Oceanography, 14 (8), 1271-1285. http://dx.doi.org/10.1175/1520-0485(1984)014<1271:OTEOAF>2.0.CO;2

Pettersson, H. 2004. Wave growth in a narrow bay. PhD thesis, Finnish Institute of Marine Research, Helsinki, Finland.

J. Portilla, F. J. Ocampo-Torres, and J. Monbaliu. 2009. Spectral Partitioning and Identification of Wind Sea and Swell. Journal of Atmospheric and Oceanic Technology, 107-122. http://dx.doi.org/10.1175/2008JTECHO609.1

Ris, R. C. 1997. Spectral modelling of wind waves in coastal areas. PhD thesis, Delft University Press, Delft, Netherlands.

I. R. Young, and L. A. Verhagen. 1996. The growth of fetch limited waves in water of finite depth. Part 1. Total energy and peak frequency. Coastal Engineering, 29 (1-2), 47-78. http://dx.doi.org/10.1016/S0378-3839(96)00006-3


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