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首页> 外文期刊>Journal of hydrometeorology >Prediction of Flash Droughts over the United States
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Prediction of Flash Droughts over the United States

机译：在美国的闪蒸干旱预测

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We examine reforecasts of flash droughts over the United States for the late spring (April-May), midsummer (June-July), and late summer/early autumn (August-September) with lead times up to 3 pentads based on the NOAA second-generation Global Ensemble Forecast System reforecasts version 2 (GEFSv2). We consider forecasts of both heat wave and precipitation deficit (P deficit) flash droughts, where heat wave flash droughts are characterized by high temperature and depletion of soil moisture and P deficit flash droughts are caused by lack of precipitation that leads to (rather than being the cause of) high temperature. We find that the GEFSv2 reforecasts generally capture the frequency of occurrence (FOC) patterns. The equitable threat score (ETS) of heat wave flash drought forecasts for late spring in the regions where heat wave flash droughts are most likely to occur over the north-central and Pacific Northwest regions is statistically significant up to 2 pentads. The GEFSv2 reforecasts capture the basic pattern of the FOC of P-deficit flash droughts and also are skillful up to lead about 2 pentads. However, the reforecasts overestimate the P-deficit flash drought FOC over parts of the Southwest in late spring, leading to large false alarm rates. For autumn, the reforecasts underestimate P-deficit flash drought occurrence over California and Nevada. The GEFSv2 reforecasts are able to capture the approximately linear relationship between evaporation and soil moisture, but the lack of skill in precipitation forecasts limits the skill of P-deficit flash drought forecasts.
机译：我们基于NOAA第二代全球集合预报系统REFORRECASTS版本2（GEFSv2），研究了美国春季末（4月至5月）、仲夏（6月至7月）和夏末/初秋（8月至9月）的短暂干旱的重新预报，提前期可达3个五分之一。我们考虑热浪和降水亏缺（P赤字）的快速干旱预报，其中热浪急速干旱的特征是高温和土壤水分的消耗，而磷亏缺的快速干旱是由于缺乏降水导致的（而不是导致高温）的原因。我们发现，GEFSv2重新预测通常捕捉到发生频率（FOC）模式。在中北部和太平洋西北部地区最有可能发生热浪暴发旱灾的地区，晚春热浪暴发旱灾预测的公平威胁分数（ETS）在统计上具有显著性，高达2个五分。GEFSv2的再预测捕捉到了缺磷闪电干旱FOC的基本模式，并且能够熟练地预测大约2个五分之一。然而，重新预测高估了春季末西南部部分地区的缺磷闪旱FOC，导致了较大的误报率。就秋季而言，重新预测低估了加州和内华达州出现缺磷闪旱的可能性。GEFSv2重新预测能够捕捉到蒸发和土壤湿度之间的近似线性关系，但缺乏降水预测技能限制了缺磷闪电干旱预测的技能。

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