The Role of Land Atmosphere Interactions on Quantitative Precipitation Forecasts and Convective Initiation over the Southern Great Plains

加强对美国大平原南部暖季降水过程的了解是美国气象研究计划的一项研究重点。利用国际H2O项目(IHOP)的观测资料，首席研究人员将研究多尺度的地面-地面/大气相互作用及其对SGP深层对流的启动和加强的影响，以改进暖季降水的诊断和预报。研究人员将使用气孔阻力/生物物理测量来表征气孔阻力、蒸腾作用以及SGP典型地貌上水汽交换的时间和空间变化。研究活动的大致轮廓包括：(1)修改与土壤水分/土壤温度同化有关的陆面模式(LSM)物理，基于光合作用的陆面模式增强，以及考虑漫射辐射和明显的地形效应，以了解土壤水分和植被表示对对流和对流降水的影响；(2)利用幕式对流风暴分析测试LSM，以及使用高分辨率耦合中尺度数值模式进行为期一个月的模拟；(3)利用集合分析和统计-动力因子分离分析，诊断导致对流潜势和对流降水的土壤、植被和大气对流之间的耦合/相互作用路径的性质。这项研究将讨论需要调查陆地表面、行星边界层和云辐射过程之间的复杂相互作用，及其对深对流发展的影响，并改进模式定量降水预报技术。作为更广泛的影响，这项研究包括参与一个合作项目，并将本科生和研究生的研究论文整合到研究活动中。这项研究的成功完成可能会对对流爆发的预报产生积极的影响。

Improving the understanding of warm-season precipitation processes in the U.S. Southern Great Plains (SGP) is a research priority of the U.S. Weather Research Program. Using observations from the International H2O Project (IHOP), the Principal Investigators will study the multi-scale land-surface/atmosphere interactions and their impacts on the initiation and intensification of deep convection in the SGP and improve the diagnosis and prediction of warm season rain. The investigators will use stomatal resistance / biophysical measurements to characterize the temporal and spatial variations of stomatal resistance, transpiration and hence water vapor exchange over typical landscapes in the SGP. A broad outline of the research activities includes: (1) modifications to land surface model (LSM) physics relating to soil moisture / soil temperature assimilation, photosynthesis-based land surface model enhancements, and consideration of diffuse radiation and explicit terrain effects, in order to understand the effects of soil moisture and vegetation representation on convection and convective precipitation; (2) testing of the LSM using episodic convective storm analyses, as well as month long simulations using a high resolution coupled mesoscale numerical model ; and (3) diagnosing the nature of the coupled / interactive pathways between the soil, vegetation and atmospheric convection leading to the convective potential and the convective precipitation using ensemble and statistical-dynamical factor separation analyses. The study will address the need to investigate the complex interactions between land surface, planetary boundary layer, and cloud-radiation processes, and their effects on the development of deep convection and improve model quantitative precipitation forecast skills. As a broader impact, the study involves participation in a collaborative program and integrating undergraduate and graduate student research theses within the research activities. Successful completion of the research may have a positive impact on the forecasting of convective initiation.