Department of Science and Research, Islamic Azad University and Iran Meteorological Organization, P.O. Box 14965-114
Institute of Geophysics, University of Tehran, P.O. Box 14155-6466, Tehran, Iran
The objective of this study is the assessment survey of short-term wave prediction in the southern Caspian Sea by using the WAM wave model. For the run of the WAM model, a 35×45 rectangularity grid is used, covering 36.5º to 47.5º N in latitude and 46.5º to 55º E in longitude with 15 grid interval in both directions. In order to survey the ability of the model in forecasting wave, two different atmospheric conditions, one with weak and the other with strong wind, are considered. The required wave model input data are the Caspian Sea topography and 10 meter wind field. The weak wind input data are extracted from the transmitted GTS synoptic data of regional centers to the Forecasting Center of Iran Meteorological Organization, the storm wind input data are extracted from the output of MM5 mesoscale model which is run by using the AVN data of NOAA Center and the topography input data are extracted from the Caspian Sea Hydrography map of Iran, Armed Forces Geographical Organization. Before transforming input data into the WAM model format, they were interpolated into the Caspian Sea grid. Making use of written programs in FORTRAN, GrADS and MATLAB languages, the wave model output is transformed into suitable graphics including contour map of wave height, wind field, diagram of Custer, 1-D frequency spectrum and 2-D angular spectrum.
According to wave model outputs of the Caspian Sea, the results of this research are as follows:
-Because of existence of evident changes in measurement and gradient of wave height in relation to different atmospheric conditions that are descriptive of model sensibility to wind input data and very much consistent with wind and wave field that is specification of prediction wave in closed basins, the WAM wave model is able to predict wave characteristics as short-term in the Caspian Sea.
-Because of the existence of conformity wave double-peaked frequency spectra of the Caspian Sea with Strekalov and Massels’ researches about wave frequency spectra of the Caspian Sea, the WAM wave model is able to predict in the short-term and display accurate pattern of wave frequency spectra in the Caspian Sea.
-Because of the existence of right skewness of wave frequency spectra of the southern Caspian Sea, number of waves taking part in propagating wave spectral energy is related to frequency domain higher than peak frequency, but integrally the maximum amount of wave spectral energy is propagated by the waves with frequency lower than peak frequency.
-Because of the existence of good relativity agreement between the WAM model output and the wave data of the Anzali bouy when they are compared in order to survey model verification, it is found that the WAM model is able to predict wave characteristics in the short-term in the southern Caspian Sea with high relativity accuracy.