Sensitivity of extratropical cyclone characteristics to horizontal resolution in the ECMWF model
Sensitivity of extratropical cyclone characteristics to horizontal resolution in the ECMWF model
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DOI：
10.1256/qj.05.212
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发表时间：
2006-07
影响因子：
8.9
通讯作者：
Thomas Jung;S. Gulev;I. Rudeva;V. Soloviov
中科院分区：
文献类型：
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作者：
Thomas Jung;S. Gulev;I. Rudeva;V. Soloviov
利用欧洲中期天气预报中心（ECMWF）模式的一组季节预报（1982-2001），研究了冬季（12 - 3月）北方半球热带气旋特征对水平分辨率的敏感性。采用三种不同的水平分辨率（TL 95、TL 159和TL 255）。为了检验模拟的真实性，将模型结果与ERA-40再分析数据进行了比较。气旋跟踪是通过将自动跟踪方案应用于6小时平均海平面气压数据来完成的。结果表明，ECMWF模式中的许多对流层外气旋的关键特征对水平分辨率高度敏感，例如，低分辨率版本（TL 95）仅模拟了重新分析的对流层外气旋总数的约60%。特别敏感的区域包括北方太平洋、北极、巴芬湾和拉布拉多海以及地中海。对于后一个区域，即使是相对高分辨率的模型（TL 255）也明显低估了热那亚气旋发生的数量。此外，它表明，在某些地区，如主要的北方风暴路径的入口区域，模式赤字是不敏感的水平分辨率的增加。同样的分析已经被重复用于高分辨率业务ECMWF分析（2000-2004），在不同的总波数（TL 95，TL 159，TL 255和TL 511）截断，以分离分辨率差异的动力学效应与纯光谱截断。结果表明，对于强气旋，改变水平分辨率的动力学效应超过截断效应，而对于浅气旋，截断效应占主导地位。版权所有© 2006年皇家气象学会
The sensitivity to horizontal resolution of northern hemisphere extratropical cyclone characteristics during the wintertime (December–March) is investigated using a set of seasonal forecasts (1982–2001) with the European Centre for Medium‐Range Weather Forecasts (ECMWF) model. Three different horizontal resolutions (TL95, TL159 and TL255) are employed. In order to test the realism of the simulations, the model results are compared with those obtained from ERA‐40 re‐analysis data. The cyclone tracking is accomplished by applying an automatic tracking scheme to six‐hourly mean‐sea‐level pressure data. It is shown that many of the key characteristics of extratropical cyclones in the ECMWF model are highly sensitive to horizontal resolution, with the low‐resolution version (TL95), for example, simulating only about 60% of the re‐analysed total number of extratropical cyclones. Regions found to be particularly sensitive include the northern Pacific, the Arctic, Baffin Bay and the Labrador Sea, as well as the Mediterranean Sea. For the latter region it is shown that even the relatively high‐resolution version of the model (TL255) significantly underestimates the number of cases of Genoa cyclogenesis. Furthermore, it is shown that in some regions, such as the entrance regions of the major northern hemisphere storm tracks, model deficits are insensitive to increases in horizontal resolution. The same analysis has been repeated for the high‐resolution operational ECMWF analysis (2000–2004), truncated at different total wave numbers (TL95, TL159, TL255 and TL511) in order to separate dynamical effects of differences in resolution from those due to pure spectral truncation. It is found that the dynamical effect of changing horizontal resolution dominates over the truncation effect for intense cyclones, whereas the truncation effect dominates for shallow cyclones. Copyright © 2006 Royal Meteorological Society