风拖曳力系数和曼宁系数对风暴潮流模拟的影响

利用0205号威马逊台风期间实测风暴增水和风暴潮流数据,采用NCEP FNL和台风模型风场的融合风场作为驱动项,建立了覆盖东海的三维风暴潮流数值模型,研究风拖曳力系数和曼宁系数对风暴增水和风暴潮流的影响。计算结果表明:(1)风拖曳力系数取值应考虑随风速变化。表层风暴潮流受风拖曳力系数影响较大,中层和底层风暴潮流基本不受影响。(2)风暴潮流结构在一定程度上取决于曼宁系数;曼宁系数对中层和底层风暴潮流影响大于表层,曼宁系数越大,底摩擦阻力越大,风暴潮流垂向分层越明显。(3)风暴增水和风暴潮流对曼宁系数的响应不同,建立模型时,应同时率定风暴增水和风暴潮流。

Influence of wind drag coefficient and Manning coefficient on storm current simulation

Based on the observed data during typhoon Rammasun, a 3-D numerical model of storm current was established by using coupled wind field from NCEP FNL and typhoon wind field model as the driving term, and then the responses of storm current simulation to the values of wind drag coefficient and Manning coefficient were studied. The analysis results showed as follows: (1) The value determination of wind drag coefficient should consider the wind speed variation. Wind drag coefficient will greatly impact surface storm current, but almost not affect the middle and bottom storm current. (2) The vertical structure of storm current can be impacted by Manning coefficient, which has more influence on the middle and lower storm currents than the surface layer. The larger the Manning coefficient is, the greater the bottom friction is, and vertical stratification of storm currents is more obvious. (3)The storm surge and storm current has different response to Manning coefficient, and the storm current numerical model should be calibrated both by storm surge and storm current.