Tracking the uncertainty in flood alerts driven by grand ensemble weather predictions
Tracking the uncertainty in flood alerts driven by grand ensemble weather predictions
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DOI：
10.1002/met.132
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发表时间：
2009-03
影响因子：
2.7
通讯作者：
Yi He;F. Wetterhall;H. Cloke;F. Pappenberger;Matthew D. Wilson;J. Freer;G. McGregor
中科院分区：
文献类型：
--
作者：
Yi He;F. Wetterhall;H. Cloke;F. Pappenberger;Matthew D. Wilson;J. Freer;G. McGregor
将数值天气预报（NWP）纳入洪水警报系统可以将预报提前时间从几小时增加到几天。然而，来自单一预报中心的单一数值预报是不够的，因为它涉及相当大的不可预测的不确定性，并可能导致大量的错误或错过的警告。利用来自各气象中心的多个NWP对流域水文进行天气预报，可以大大改善洪水预警。通过“THORPEX交互式全球大集合”（TIGGE）提供全球集合天气预报系统，为开发最先进的早期洪水预报系统提供了新的机会。本文介绍了一个案例研究，使用TIGGE数据库洪水预警的中尺度流域（4062平方公里）位于英格兰中部地区。首次尝试建立由TIGGE集合预报驱动的大气-水文-水力耦合级联系统。概率流量和洪水淹没预测作为最终产品，研究使用TIGGE数据库的潜在效益。研究表明，降水输入的不确定性占主导地位，并通过级联链传播。目前的NWP没有代表这样一个相对较小的流域，这表明需要提高NWP分辨率和/或分解技术，以缩小气象和水文之间的空间差距的空间降水变异。流量预测的范围因中心而异，但一般都很大，并意味着很大程度的不确定性。然而，结果表明，TIGGE数据库是一个很有前途的工具，预测洪水淹没，与雨量计观测驱动。版权所有© 2009皇家气象学会
The incorporation of numerical weather predictions (NWP) into a flood warning system can increase forecast lead times from a few hours to a few days. A single NWP forecast from a single forecast centre, however, is insufficient as it involves considerable non‐predictable uncertainties and can lead to a high number of false or missed warnings. Weather forecasts using multiple NWPs from various weather centres implemented on catchment hydrology can provide significantly improved early flood warning. The availability of global ensemble weather prediction systems through the ‘THORPEX Interactive Grand Global Ensemble’ (TIGGE) offers a new opportunity for the development of state‐of‐the‐art early flood forecasting systems. This paper presents a case study using the TIGGE database for flood warning on a meso‐scale catchment (4062 km2) located in the Midlands region of England. For the first time, a research attempt is made to set up a coupled atmospheric‐hydrologic‐hydraulic cascade system driven by the TIGGE ensemble forecasts. A probabilistic discharge and flood inundation forecast is provided as the end product to study the potential benefits of using the TIGGE database. The study shows that precipitation input uncertainties dominate and propagate through the cascade chain. The current NWPs fall short of representing the spatial precipitation variability on such a comparatively small catchment, which indicates need to improve NWPs resolution and/or disaggregating techniques to narrow down the spatial gap between meteorology and hydrology. The spread of discharge forecasts varies from centre to centre, but it is generally large and implies a significant level of uncertainties. Nevertheless, the results show the TIGGE database is a promising tool to forecast flood inundation, comparable with that driven by raingauge observation. Copyright © 2009 Royal Meteorological Society