Dynamics of Heavy Precipitation over Mesoscale Mountains

中尺度山脉强降水动力学

• 批准号: 0344237
• 负责人: Gary Lackmann
• 金额: --
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0344237&HistoricalAwards=false
• 关键词: Dynamics; Heavy; Precipitation; over; Mesoscale

The objective of this research is to advance scientific understanding of orographic rainfall. Three major questions will be addressed:(1) In addition to the moist Froude number, what are other major non dimensional parameters that control the propagation of orographically induced mesoscale convective systems over mountains?(2) What are the formation and propagation mechanisms of convective cells embedded in an orographic mesoscale convective system?(3) How does an upper-level jet streak couple with the low-level flow to create an environment that is highly favorable for heavy orographic precipitation?In order to address the first question, the Principal Investigator will extend previous studies to investigate other major control parameters for a conditionally unstable orographic flow. A series of idealized numerical experiments will be performed using a mesoscale numerical model to study the effects of basic flow speed, instability, moisture content, aspect ratio of the mountain, Coriolis force and vertical wind shear on moist flow regimes. In order to address the second question, the Principal Investigator hypothesizes that advection is the major mechanism for the generation of convective cells. This advection mechanism will be tested by performing a series of numerical experiments. Regarding the third question, it is hypothesized that there is a vertical coupling process between the boundary layer flow and upper-level jet streak that creates an environment that is highly favorable for heavy orographic precipitation. A mesoscale numerical model will be adopted to perform real-case numerical experiments to help answer this question. The intellectual merit of this approach is largely derived from the unique multi-faceted synthesis of idealized numerical modeling, real data numerical modeling and observational data analyses as applied to the problem of why heavy orographic rainfall occurs over mesoscale mountains.The broader impacts will be achieved by utilizing the research findings for the development of improved forecast techniques of extreme orographic rainfall predictions. It is anticipated that this will result in the saving of lives and the reduction of property losses.

这项研究的目的是提高对地形降雨的科学认识。 三个主要问题将被解决：（1）除了湿弗劳德数，还有什么其他主要的无量纲参数，控制地形引起的中尺度对流系统的传播在山区？(2)地形中尺度对流系统中对流单体的形成和传播机制是什么？(3)高空急流条纹如何与低空气流耦合，以创造一个非常有利于强地形降水的环境？为了解决第一个问题，主要研究者将扩展以前的研究，以调查其他主要控制参数的条件不稳定的地形流。 将利用中尺度数值模式进行一系列理想化数值试验，研究基本流速、不稳定性、含水量、山体纵横比、科氏力和垂直风切变对湿流状况的影响。 为了解决第二个问题，主要研究者假设平流是对流单体产生的主要机制。 这一平流机制将通过一系列数值试验进行检验。 关于第三个问题，假设边界层气流和高空急流条纹之间存在垂直耦合过程，从而产生非常有利于强地形降水的环境。 我们将采用一个中尺度数值模式来进行实际的数值试验，以帮助回答这个问题。 这种方法的智力价值主要来自于理想化数值模拟、真实的数据数值模拟和观测数据分析的独特多方面综合，应用于中尺度山区发生强地形降雨的原因问题，通过利用研究结果改进极端地形降雨预报技术，将实现更广泛的影响。 预计这将挽救生命，减少财产损失。