Sensitivity of Northern Hemisphere Cyclone Detection and Tracking Results to Fine Spatial and Temporal Resolution using ERA5
Sensitivity of Northern Hemisphere Cyclone Detection and Tracking Results to Fine Spatial and Temporal Resolution using ERA5
复制标题
使用 ERA5 北半球气旋探测和跟踪结果对精细空间和时间分辨率的敏感性
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发表时间：
2021
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通讯作者：
D. Barber
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作者：
A. Crawford;E. Schreiber;Nathan Sommer;M. Serreze;J. Stroeve;D. Barber
拉格朗日探测和跟踪算法经常被用于研究温带气旋的发展、分布和趋势。过去的研究表明，这些算法的结果对网格输入场的空间和时间分辨率都很敏感，较粗的分辨率通常会低估气旋频率，因为无法捕捉到弱、小和短寿命的系统。欧洲中期天气预报中心(ERA5)的第五代大气再分析提供了更精细的分辨率，因此比以前的全球再分析提供了更准确的风暴位置和发展信息。然而，我们的敏感性测试表明，以最好的分辨率使用ERA5海平面气压场并不一定会带来更好的气旋检测和跟踪。如果在探测海平面气压的最小值时使用相同数量的近邻(就像过去的研究一样)，更精细的空间分辨率会导致更多的噪声，从而不切实际地打破多中心气旋。相反，使用公共搜索距离(具有更高分辨率的更多邻居)可以在不平滑输入的情况下解决问题。这样做还会使气旋频率、寿命和平均深度对细化100公里以上的空间分辨率不敏感。结果使用6小时和3小时的时间分辨率只有很小的差别，但使用1小时的时间分辨率和最大允许传播速度150公里/小时-1会导致不切实际的轨迹分裂。这可以通过增加最大传播速度来抵消，但对于几个气旋特征来说，对时间分辨率的适度敏感性仍然存在。因此，我们建议在将现有算法应用于精细于3-h的时间分辨率并仔细评估算法设置时保持谨慎。
Lagrangian detection and tracking algorithms are frequently used to study the development, distribution, and trends of extratropical cyclones. Past research shows that results from these algorithms are sensitive to both spatial and temporal resolution of the gridded input fields, with coarser resolutions typically underestimating cyclone frequency by failing to capture weak, small, and short-lived systems. The fifth-generation atmospheric reanalysis from the European Centre for Medium-Range Weather Forecasts (ERA5) offers finer resolution, and therefore more precise information regarding storm locations and development than previous global reanalyses. However, our sensitivity tests show that using ERA5 sea-level pressure fields at their finest possible resolution does not necessarily lead to better cyclone detection and tracking. If a common number of nearest neighbors is used when detecting minima in sea-level pressure (like past studies), finer spatial resolution leads to noisier fields that unrealistically break up multi-center cyclones. Using a common search distance instead (with more neighbors at finer resolution) resolves the issue without smoothing inputs. Doing this also makes cyclone frequency, lifespan, and average depth insensitive to refining spatial resolution beyond 100 km. Results using 6-h and 3-h temporal resolutions have only minor differences, but using 1-h temporal resolution with a maximum allowed propagation speed of 150 km h-1 leads to unrealistic track splitting. This can be counteracted by increasing the maximum propagation speed, but modest sensitivity to temporal resolution persists for several cyclone characteristics. Therefore, we recommend caution if applying existing algorithms to temporal resolutions finer than 3-h and careful evaluation of algorithm settings.