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基于四种资料的超强台风利奇马(1909)期间海面风变化特征对比分析

Comparision Between 4 Datasets Applied in Characteristics Analysis of Sea Surface Wind During Super Typhoon Lekima (1909)

  • 摘要: 本文对海洋气象漂流观测仪实测、CMA最佳路径数据集、第5代全球气象再分析产品(ERA5)、交叉检验多平台融合矢量风场(CCMP)四种资料的海面风在超强台风“利奇马”期间的变化特征进行分析。ERA5、CCMP两种分析/再分析风资料与实测风的对比分析表明:(1)风速:当风力<10级时,漂流观测仪轨迹上的ERA5、CCMP风速较漂流观测仪实测风速偏小;将漂流观测仪实测风速订正到10 m高度,风力≤5级时偏差(Bias)绝对值最小,ERA5(CCMP)为4.3 m s−1(4.6 m s−1),风力为7~9级时Bias绝对值最大,约9.2~10.2 m s−1;“利奇马”近中心海域ERA5、CCMP最大风速较CMA最佳路径数据集偏小,ERA5(CCMP)偏小约10.7 m s−1(4.6 m s−1);ERA5(CCMP)最大风速极值较CMA最佳路径数据集偏低54.5%(12.7%)。(2)风向:ERA5、CCMP与漂流观测仪实测风向相关系数接近于0;风力≤5级时风向较实测偏右,风力>5级时偏左。(3)ERA5、CCMP风向、风速在“利奇马”近中心海域偏差明显,远离中心海域二者吻合度较高。通过对ERA5、CCMP资料进一步分析发现:CCMP能清楚描述热带气旋风场结构及演变过程,“利奇马”为超强台风时结构参数η=Vr/Vmax分布上有闭合环状结构,表明该区域有环状大风速带;“利奇马”强迫时间Tf分布于移动路径两侧,ERA5(CCMP)最大强迫时间为45 h(54 h)。

     

    Abstract: Four types of sea surface wind data drifting buoy observation data, China Meteorological Administration (CMA) tropical cyclone database, ECMWF Reanalysis v5 dataset (ERA5), Cross-Calibrated Multi-Platform dataset (CCMP) are compared and analyzed during the super typhoon Lekima, and the comparision in sea surface wind characteristics between the ERA5/CCMP data and drifting buoy observation data is primarily discussed. The following are the main conclusions: (1) Characters of wind speed: ERA5/CCMP wind speed on the track of the drifting buoy is obviously lower than that of the drifting buoy observation when wind speed is less than grade 10. After the wind speed for the drifting buoy at 0.6 m is revised to 10 m, the Bias is smallest when the wind speed is less than or equal to grade 5 (−4.3 m s−1 for ERA5 and −4.6 m s−1 for CCMP) and largest when the wind speed is between grades 7 and 9 (approximately in the range of −9.2 to −10.2 m s−1). The maximum wind speed of ERA5/CCMP near the center of Likima is less than that of the CMA tropical cyclone database; it is approximately 10.7 m s−1 (4.6 m s−1) for ERA5 (CCMP). The maximum wind speed of ERA5 (CCMP) is 54.5% (12.7%) lower than that of the CMA database. (2) Characters of wind direction: The correlation coefficient between ERA5/CCMP wind direction and the corresponding drifting buoy observation is almost 0. The wind direction is rightward than measured when wind speed is less than or equal to grade 5; otherwise, it is leftward than measured. (3) Wind direction and speed deviations between ERA5 and CCMP become obvious near the center of Lekima, but more consistency is observed considerably away from the center. Through further analysis of the ERA5 and CCMP data, we observe that CCMP can more clearly describe the wind field structure and evolution process of Lekima. Distribution of the wind structure parameter η = Vr/Vmax appears like a closed-ring structure when Lekima is at the super typhoon level, meaning the presence of a large wind speed belt in this region. Typhoon forcing time Tf is distributed on both sides of Lekima’s moving path. The maximum forcing time of ERA5 (CCMP) is 45 h (54 h).

     

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