Heavy Precipitation at the Alpine South Side and Saharan Dust over Central Europe: A Predictability Study Using TIGGE
Heavy Precipitation at the Alpine South Side and Saharan Dust over Central Europe: A Predictability Study Using TIGGE
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DOI：
10.1175/waf-d-10-05060.1
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发表时间：
2011-12
影响因子：
2.9
通讯作者：
L. Wiegand;Arwen Twitchett;C. Schwierz;P. Knippertz
中科院分区：
文献类型：
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作者：
L. Wiegand;Arwen Twitchett;C. Schwierz;P. Knippertz
2008 年 5 月 26 日左右，一股明显的位涡 (PV) 流从北大西洋渗透到地中海西部，随后沙尘在西北非洲马格里布地区广泛流动，随后向北输送到中欧。与此同时，地中海上空的强烈南风气流导致欧洲阿尔卑斯山迎风面出现强降水和洪水。本研究使用连续和基于特征的误差测量以及集合相关技术，调查了参与观测系统研究和可预测性实验（THORPEX）互动大全球集合（TIGGE）项目的九个气象中心的业务集合预测中这一高影响事件的天气和中尺度方面的预报质量和可预测性。 TIGGE 是一个最近建立的项目，以标准化格式提供集合预报，它允许采用令人兴奋的新多模型方法来研究高影响天气及其动态等的可预测性。这项研究的主要结论是： 1) 光伏流光预报的质量随着交付时间的增加而降低，显示出罗斯贝波过弱的总体趋势； 2) 当关注拖缆周围的区域时，大多数模型显示出与系综扩散相同或更大的均方根误差（欠色散行为）； 3）如果与各中心自己的分析而不是ECMWF分析进行比较，误差可减少约50%； 4) 撒哈拉沙漠上空的峰值风速往往被低估，模型公式的差异主导了光伏拖缆表示的差异； 5) 4 天累积降水量的集合平均多模式预报对于成功的恶劣天气预警来说似乎足够准确。
Around 26 May 2008 a pronounced potential vorticity (PV) streamer penetrated from the North Atlantic into the western Mediterranean Sea followed by widespread dust mobilization over the Maghreb region of northwest Africa and a subsequent northward transport into central Europe. At the same time, strong southerly flow over the Mediterranean Sea caused heavy precipitation and flooding at the windward side of the European Alps. Using continuous and feature-based error measures, as well as ensemble correlation techniques, this study investigates the forecast quality and predictability of synoptic and mesoscale aspects of this high-impact event in operational ensemble predictions from nine meteorological centers participating in The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) project. TIGGE is a recently established program providing ensemble forecasts in a standardized format, which allows for an exciting new multimodel approach to investigating the predictability of, for example, high-impact weather and its dynamics. The main conclusions from this study are that 1) the quality of the PV streamer forecasts degrades with lead time showing a general tendency toward too weak Rossby wave; 2) when focusing on the region around the streamer, most models show root-meansquare errors of the same magnitude or larger than the ensemble spread (underdispersive behavior); 3) errors are reduced by about 50% if the comparison is made to each center’s own analysis instead of the ECMWF analysis; 4) peak wind speeds over the Sahara tend to be underpredicted, with differences in model formulation dominating over differences in the representation of the PV streamer; and 5) ensemble-mean multimodel forecasts of 4-day accumulated precipitation appear accurate enough for a successful severe-weather warning.