| 摘要: |
| 本文采用波浪订正的Ekman模型，研究分析了三种Stokes漂流近似公式（单波公式、e指数公式、Phillips谱近似公式）对海洋表层流场估算的影响。海表总流场由海表面高度（SSH）数据计算的地转流和海浪模式WAVEWATCH Ⅲ输出结果计算的非地转流组成，并采用拉格朗日浮标观测数据对计算结果进行了验证。研究表明，随着Stokes漂流近似公式精度的提高，其计算的拉格朗日流速更接近于谱积分公式的计算结果，更贴近拉格朗日浮标观测数据。与谱积分公式计算的海表拉格朗日流速相比，单波公式的平均相对偏差为0.0834，e指数公式的平均相对偏差为0.0392，Phillips谱近似公式的平均相对偏差为0.0101，说明Phillips谱近似公式在不同风速下均能对谱积分公式有良好的近似效果。在低风速条件下，由Stokes漂流近似公式精度引起的海洋表层流场估算误差可以忽略不计，但随着风速增加，由近似公式精度引起的偏差逐渐变大，此时应该选择Phillips谱近似公式计算Stokes漂流，来减小误差。 |
| 关键词: 波浪订正的Ekman模型 WAVEWATCH III Stokes漂流近似公式 海洋表层流场 |
| DOI：10.11693/hyhz20180500110 |
| 分类号:P731 |
| 基金项目:国家重点研发计划项目，2016YFC1401404号；国家自然科学基金项目，41576013号。 |
附件 |
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| THE IMPACT OF THE ACCURACY OF STOKES DRIFT APPROXIMATION ON ESTIMATION OF OCEAN SURFACE CURRENT |
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BAI Chuan-Qi, SONG Jin-Bao, CHEN Hui
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Ocean College, Zhejiang University, Zhoushan 316000, China
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| Abstract: |
| Based on a wave-modified Ekman model, we studied the influence of accuracy of three Stokes drift approximations (the monochromatic wave profile, the exponential integral profile, and the Phillips profile) on the estimation of ocean surface currents. The total sea surface currents consist of two terms:geostrophic currents calculated from the sea surface height (SSH) and ageostrophic current obtained from the results of WAVEWATCH Ⅲ. We validated the estimated currents by in-situ Lagrangian drifter observations. The result shows that with the improvement of the accuracy of Stokes drift approximation, the calculated Larangian velocities are closer to the results of the spectrum integral formula and the Lagrangian drifter observations. Compared with the result of spectrum integral formula, the average relative deviation of the monochromatic wave profile is 0.0834, while the exponential integral profile is 0.0392, and the Phillips profile is 0.0101. This suggests that the Phillips profile did a good approximation to the spectral integral formula at various wind speeds. At low wind speeds, the estimation error of the ocean surface currents caused by the accuracy of the Stokes drift approximation is neglectable. However, with an increase of wind speed, the deviation caused by the accuracy of the approximation would become considerable, for which the Phillips profile should be adapted in the calculation of the Stokes drift to avoid the errors. |
| Key words: wave-modified Ekman model WAVEWATCH III Stokes drift approximation ocean surface currents |
