应用特征波预报公式进行台风浪计算的一个根本缺陷

An essential defect of forcasting formula for characteristic wind wave in the calculation of typhoon wave

Wilson方法和井岛方法均是移动风区上著名的波浪推算方法,被广泛应用于台风波浪的推算和预报上。本文通过分析指出:使用上述方法以海洋工程界所推行的风浪预报公式作台风浪推算时,所得特征波波陡将与台风浪实测波陡分布定性不符,并指出产生这种缺陷的原因。

In this paper, an essential defect is described of Wilson's method in the calculation of typhoon wave. It is common knowledge that the equivalence of characteristic wave has to be applied repeatedly for calculating wind wave in the case of moving fetch. It is shown that for a kind of relationship, such as Wilson IV, Bretschneider and Rjeplinskii etc., the characteristic wave height and period increase with the fetch in the nondimensional form, but the characteristic wave steepness decreases with the nondimensional fetch. In this case, the equivalence will make the wave steepness lower further when the wave moves from a fetch with lighter wind speed to another with stronger wind speed. Thus, the wave shape calculated by Wilson' s method will became flatter. Evidently, it is not agree with the fact that the more close to the typhoon centre the wave is, the larger the wave steepness is. Ijvma' s method by fracing wave is similar to the Wilson' s, but for the former, the projection of wave height in the changed wind direction would be used in replace of the wave height before the equivalence in applied. If so, it will cause the wave steepness still lower than the Wilson's method. It is suggested that the calculation for typhoon wave is in urgent need of developing a kind of relationship suitable for the typhoon wave which should be consistent with the fact that the characteristic wave height period and wave steepness increase with the fetcb or of developing another method.