Ecohydrologic Controls on Convective Rainfall Triggering and Space-Time Development

对流降雨触发和时空发展的生态水文控制

• 批准号: 0635787
• 负责人: Gabriel Katul
• 金额: $ 33.87万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-15 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0635787&HistoricalAwards=false
• 关键词: Ecohydrologic; Controls; Convective; Rainfall; Triggering

While summertime convective precipitation significantly contributes to the total growing season rainfall, it ranks among the least known components in the hydrologic budget of mid-latitude temperate regions. This uncertainty stems from its high space-time variability and its sensitivity to the interplay between complex eco-physiological, hydrologic, and turbulent transport mechanisms at land-atmosphere interface. To progress on the description of convective rainfall fields, both prognostic and diagnostic measures of the interrelationship between convective rainfall and land-surface forcing.H1) Prognostic: For given synoptic conditions, the integrated time history of surface water and energy fluxes, which is related to soil/vegetation characteristics, controls the timing and onset of summertime convective precipitation.H2) Diagnostic: The subsequent space-time development of convective precipitation activity, while inherently related to the internal meteorological dynamics acting at several scales, is partly controlled by a limited set of scales that can be fingerprinted from land-surface heterogeneity. This 'fingerprinting' can be statistically derived by analyzing the joint probability distributions of spatial precipitation and few land surface characteristics (e.g., topographic and land-cover indices) for different soil moisture antecedent conditions.These two hypotheses are addressed by evaluating the land-surface processes that trigger convective rainfall using low-dimensional dynamical models of the atmospheric boundary layer. The space-time structure of the convective storms is analyzed in relation to soil moisture, topography, and land cover using mutual information measures in both space and wavelet domains. The North Carolina Piedmont area is selected as a case study because of its frequent convective rainfall patterns, its summertime hydro-climatic regime, its resemblance to large parts of the Southeastern U.S. in trends of urban and agricultural land-use change, and its economic importance as the primary timberland producer in the United States.Intellectual Merit: While current stochastic hydrologic models directly address the inherent unpredictability of rainfall formation and evolution by employing highly sophisticated space-time random processes, there exists a 'deficit' in their physical formulation. On the other hand, convective precipitation models used in meteorology are primarily based on fundamental and mechanistic approaches but are routinely confronted with numerous limitations in the description of dynamically important processes at their sub-grid scale such as cloud microphysics, closure models for complex turbulent fluctuations, and approximate description of land-surface processes. The proposed approach will bridge this basic knowledge gap by offering an objective statistical characterization of the surface forcing on convective precipitation and providing benchmark measures for both hydrologic models and regional meteorological predictions.Broader impact: The proposed work will diagnose the impact of land use change on triggers of convective precipitation and its contribution to overall summertime precipitation for assessment of water resources, drought risk, and timberland viability. The proposal will train a graduate student in problems lying at the interface between hydrology, meteorology, eco-physiology, and information theory.

尽管夏季对流降水显着促进了总生长季节降雨，但它在中纬度温带地区的水文预算中排名最低的成分之一。这种不确定性源于其高时空变异性以及对陆地大气界面上复杂生态生理学，水文和湍流传输机制之间相互作用的敏感性。在描述对流降雨场的描述中进展，包括对流降雨和土地表面强迫之间相互关系的预后和诊断措施。降水活性虽然与以多个尺度作用的内部气象动力学固有相关，但部分受到有限的量表的控制，这些尺度可以从土地表面异质性中刻印出来。通过分析空间降水的联合概率分布，对于不同的土壤水分过时的条件，可以从统计上得出这种“指纹识别”。这些假设通过低降雨进行了触发型号的模型，这些假设是通过触发对有意义的降雨模型来解决的。使用空间和小波域中的相互信息测量方法，分析了对流风暴的时空结构。北卡罗来纳州皮埃蒙特地区被选为案例研究形成和演变通过采用高度复杂的时空随机过程，在其物理表述中存在“赤字”。另一方面，气象学中使用的对流降水模型主要基于基本和机械方法，但通常在其子网尺度上动态重要的过程（例如云微物理学，复杂的湍流波动的闭合模型）以及地表过程的近似描述时，通常会面临许多局限性。所提出的方法将通过提供对流降水的表面强迫的客观统计表征来弥合这一基本知识差距，并为水文模型和区域气象预测提供基准测量。BROADER的影响：拟议中的工作将诊断土地使用的影响对对流降水的影响对对流降水的影响及其对整体降水量的造成危险的贡献，以评估降水量和水资源的危险，并通过水资源，干燥的水资源，以及水资源的整体降水，以及水资源的整体降水。 该提案将培训一名研究生在水文学，气象，生态生理学和信息理论之间的界面上的问题。