Challenges in Numerical Weather Prediction of the 10 August 2020 Midwestern Derecho: Examples from the FV3-LAM

IF 3 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Weather and Forecasting Pub Date : 2023-06-01 DOI:10.1175/waf-d-23-0019.1

W. Gallus, M. Harrold

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引用次数: 1

Abstract

A severe derecho impacted the Midwestern United States on 10 August 2020, causing over 12 billion dollars in damage, and producing peak winds estimated at 63 m s−1, with the worst impacts in Iowa. The event was not forecast well by operational forecasters, nor even by operational and quasi-operational convection-allowing models. In the present study, nine simulations are performed using the Limited Area Model version of the Finite-Volume-Cubed-Sphere model (FV3-LAM) with three horizontal grid spacings and two physics suites. In addition, when a prototype of the Rapid Refresh Forecast System (RRFS) physics is used, sensitivity tests are performed to examine the impact of using the Grell-Freitas (GF) convective scheme. Several unusual results are obtained. With both the RRFS (not using GF) and Global Forecast System (GFS) physics suites, simulations using relatively coarse 13 and 25 km horizontal grid spacing do a much better job of showing an organized convective system in Iowa during the daylight hours of 10 August than the 3-km grid spacing runs. In addition, the RRFS run with 25-km grid spacing becomes much worse when the GF convective scheme is used. The 3-km RRFS run that does not use the GF scheme develops spurious nocturnal convection the night before the derecho, removing instability and preventing the derecho from being simulated at all. When GF is used, the spurious storms are removed and an excellent forecast is obtained with an intense bowing echo, exceptionally strong cold pool, and roughly 50 m s−1 surface wind gusts.

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2020年8月10日中西部Derecho数值天气预报的挑战:来自FV3-LAM的例子

2020年8月10日，一场严重的飓风袭击了美国中西部，造成超过120亿美元的损失，峰值风速估计为每小时63米，其中爱荷华州受影响最严重。可操作的预报员甚至可操作的和准可操作的对流模式都不能很好地预测这次事件。在本研究中，使用有限体积立方球模型(FV3-LAM)的有限区域模型版本进行了九次模拟，其中有三个水平网格间隔和两个物理套件。此外，当使用快速刷新预报系统(RRFS)物理原型时，进行了灵敏度测试，以检查使用Grell-Freitas (GF)对流方案的影响。得到了几个不同寻常的结果。使用RRFS(不使用GF)和全球预报系统(GFS)物理套件，使用相对粗糙的13公里和25公里水平网格间距的模拟比3公里网格间距的模拟更能显示8月10日白天爱荷华州有组织的对流系统。此外，在格网间距为25km时，采用GF对流方案时，RRFS的运行变得更差。不使用GF方案的3公里RRFS运行在derecho前一晚产生了虚假的夜间对流，消除了不稳定性，从而完全阻止了对derecho的模拟。当使用GF时，去除了虚假的风暴，并获得了强烈的弯曲回波，异常强烈的冷池和大约50 ms - 1的地面阵风的良好预报。

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来源期刊

Weather and Forecasting 地学-气象与大气科学

CiteScore

5.20

自引率

17.20%

发文量

131

审稿时长

6-12 weeks

期刊介绍： Weather and Forecasting (WAF) (ISSN: 0882-8156; eISSN: 1520-0434) publishes research that is relevant to operational forecasting. This includes papers on significant weather events, forecasting techniques, forecast verification, model parameterizations, data assimilation, model ensembles, statistical postprocessing techniques, the transfer of research results to the forecasting community, and the societal use and value of forecasts. The scope of WAF includes research relevant to forecast lead times ranging from short-term “nowcasts” through seasonal time scales out to approximately two years.