一个高分辨率的长江口台风风暴潮数值预报模式及其应用

A high-resolution numerical storm surge model in the Changjiang River Estuary and its application

利用河口海岸海洋模式(ECOM Si)建立了一个适用于长江口区风暴潮的数值预报模式.该模式采用对岸线有较好拟合能力的自然正交水平坐标系统和能分辨较复杂海底地形的垂直σ坐标系统.模式考虑了长江口径流量对风暴潮的影响,部分地考虑了天文潮和风暴潮非线性相互作用对风暴增水的影响.风暴潮预报的大气强迫场用模型气压场和模型风场.利用所建立的模式对长江口区台风风暴潮进行了8个个例模拟,模拟增水与实测增水的峰值相比较,平均绝对误差不足10cm.利用本研究建立的模式,就气象因子对风暴潮位的敏感性进行了数值试验.试验结果表明,台风中心气压降低(升高)20hPa可导致约100cm的风暴潮位升高(或降低).台风最大风速半径误差对台风增水的变化影响也较显著.试验还表明,长江径流量增加1倍(减半),可以造成风暴潮的平均增加25cm(减小13cm).天文潮位相变化对风暴增水的影响数值试验表明,当台风暴潮与天文潮在不同位相相互作用,可使风暴潮位最大增加达70cm或减小90cm.

A high-resolution numerical storm surge model in the estuary of Changjing River is developed using the ECOM-Si. Annual average discharge of the Changjiang River is incorporated into the numerical model, and the influential interaction between tide and storm surge is partly taken into account in the model as well. Feasibility of the model is verified to be using eight-case effectual and typical typhoons passing through the Changjiang River Estuary in simulating and forecasting the storm surge and the average error of the resulting storm surge is less than 10 cm. Several numerical experiments are conducted in order to test the sensitivity of the storm surge to the meteorological parameters such as the minimum sea surface pressure and maximum wind radius of typhoon. The effect of interaction between tide and storm surge as well as the discharge on the storm surge are also numerically tested. The sensitive experiment results indicate that the role of the meteorological parameters,Changjiang River discharge,and the tide-surge interaction in the storm surge is remarkable and therefore should be consider in the operational storm surge forecasting.