RUI: Precipitation Regimes Associated with Inverted Troughs

RUI：与倒槽相关的降水状况

• 批准号: 9610356
• 负责人: Robert Weisman
• 金额: --
• 依托单位: St. Cloud State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2001-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9610356&HistoricalAwards=false
• 关键词: RUI; Precipitation; Regimes; Associated; Inverted

9610356 Weisman Cyclones and frontal systems associated with inverted troughs have been found to be a frequent occurrence in the Central United States. A 6-year survey has shown 247 cases involving inverted troughs in the Central U.S. between the lee of the Rockies and the Mississippi River. This relatively frequent phenomenon is not accounted for in current polar front models. The goal of this project is to build upon prior research by determining the dynamic support for the precipitation distribution during inverted trough cases. The preliminary survey of inverted trough cases has determined that there are two primary precipitation distributions in cases involving an inverted trough: 1) most of the precipitation falls downstream of the trough in the older, modified polar air mass (Ahead cases) and 2) most of the precipitation falls upstream of the trough in the fresh supply of arctic air (Behind cases). In the 6-year survey of inverted troughs, 42% of the cases fell into the Ahead category, while only 9% fell into the Behind category, but several of the Behind cases were major blizzards. The remaining cases were a combination of the two categories. This project will involve compositing the Ahead and Behind cases for comparison of forcing mechanisms. Calculations of lifting mechanisms such as warm advection, frontogenesis, and quasi-geostrophic forcing will be performed for each composite in order to identify the relative importance of these processes in the two categories and to enable comparisons between the two precipitation signals. It is hoped that the results of this project will provide a conceptual model for forecasters to use in real time to improve rain and snow forecasting during inverted trough cases. ***

9610356 韦斯曼 气旋和与倒槽相关的锋面系统在美国中部经常出现。 一项为期 6 年的调查显示，美国中部落基山脉背风处和密西西比河之间有 247 起倒槽事故。当前的极锋模型并未考虑到这种相对频繁的现象。 该项目的目标是在先前研究的基础上，确定倒槽情况下降水分布的动态支持。 对倒槽案例的初步调查确定，在涉及倒槽的情况下，有两种主要的降水分布：1）大部分降水落在较旧的、经过修改的极地气团中的槽下游（前案例）和2）大部分降水落在北极新鲜空气供应中的槽上游（后案例）。 在为期6年的倒谷调查中，42%的案例属于Ahead类别，而只有9%属于Behind类别，但其中几个Behind案例是大暴风雪。 其余案例是这两类的组合。 该项目将涉及合成Ahead 和Behind 案例以比较强制机制。 将对每种复合材料进行诸如暖平流、锋生和准地转强迫等提升机制的计算，以便确定这些过程在两个类别中的相对重要性，并能够在两个降水信号之间进行比较。 希望该项目的结果将为预报员提供一个概念模型，供预报员实时使用，以改进倒槽情况下的雨雪预报。 ***