Evaluation of surface wind fields for prediction of directional ocean wave spectra during Hurricane Sandy
Evaluation of surface wind fields for prediction of directional ocean wave spectra during Hurricane Sandy
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DOI：
10.1016/j.coastaleng.2017.04.003
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发表时间：
2017-07
影响因子：
4.4
通讯作者：
V. Bennett;R. Mulligan
中科院分区：
文献类型：
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作者：
V. Bennett;R. Mulligan
飓风桑迪是大西洋盆地有史以来最大的风暴，大浪和高风暴潮造成了广泛的沿海破坏。在本研究中，研究了三种不同的空间变化的地面风和大气压力场，用于预测或预报大陆架上的飓风波。这些风场包括两个二维参数风模型（Holland模型，H80；广义非对称荷兰模型，GAHM）和一个具有数据同化的三维大气模型（WeatherFlow区域大气模拟系统，WRAMS）。利用Delft3D-SWAN耦合水动力和海浪模型在区域网格上驱动波浪预测，并将体波统计和定向波谱与近海波浪浮标观测结果进行比较，研究复杂风场差异对海面演变预测的影响。不同风场体波参数的时空分布是不同的。WRAMS风场与显著波高观测结果吻合度最高，其次是GAHM和H80风场，9个站点的平均相关系数分别为0.91、0.82和0.75。飓风桑迪的定向波谱主要在飓风的左两个象限呈双峰型，与浮标观测结果一致。结果表明，在有详细观测资料的情况下，对风场描述最好的区域大气风模式是最适宜的飓风波后推强迫。但是，在波浪模型中使用包含多个等风线风的参数化涡模型时，结果与波浪观测结果非常吻合，并且对于预测飓风海面状况也很有用。本研究的结果与其他热带气旋相关，这些热带气旋经历温带过渡或受中纬度其他大气扰动的影响，导致风暴具有大空间尺寸和高不对称性。
Hurricane Sandy was the largest storm on historical record in the Atlantic Ocean basin with extensive coastal damage caused by large waves and high storm surge. In this study, three different spatially-varying surface wind and atmospheric pressure fields that are used for forecasting or hindcasting hurricane waves on the continental shelf are investigated. These wind fields include two 2D parametric wind models (Holland model, H80; Generalized Asymmetric Holland Model, GAHM), and a 3D atmospheric model with data assimilation (WeatherFlow Regional Atmospheric Modelling System, WRAMS). These wind fields are used to drive wave hindcasts using coupled Delft3D-SWAN hydrodynamic and ocean wave models on a regional grid, and the bulk wave statistics and the directional wave spectra are compared to observations at offshore wave buoys to investigate the impact of differences between the complex wind fields on predictions of the sea surface evolution.The spatial and temporal distribution of bulk wave parameters are different for each wind field. The WRAMS wind field produces wave model predictions in the best agreement with significant wave height observations, followed by the GAHM and H80 wind fields, with mean correlation coefficients of 0.91, 0.82 and 0.75, respectively averaged over 9 sites. The directional wave spectra for Hurricane Sandy was bi-modal predominantly in the two left quadrants of the hurricane, in agreement with buoy observations. The results indicate that a regional atmospheric wind model that has the best description of the wind field is the most appropriate forcing for hindcasting hurricane waves when detailed observations are available. However a parametric vortex model that incorporates wind at multiple isotachs results in very good agreement with wave observations when used in the wave model, and is a useful too for forecasting hurricane sea surface conditions. The results of this study are relevant for other tropical cyclones that undergo extratropical transition or are influenced by other atmospheric disturbances at mid-latitudes, resulting in storms with large spatial size and high asymmetry.