Collaborative research on quantifying the impacts of atmospheric and land surface heterogeneity and scale on soil moisture-precipitation feedbacks

本项目研究土壤湿度与降水之间的潜在反馈关系。正反馈将意味着土壤湿度的增加导致降水的增加，因为更湿润的地表为随后的降雨提供了蒸发源。在这种情况下，降水将导致土壤更湿润，进而导致进一步降水，而降水不足可能导致土壤水分不足，从而导致降水进一步减少，导致长期干旱。本研究主要通过两种相互关联的方法评估大气和地表异质性以及空间尺度对土壤水分-降水耦合的影响，主要是在日尺度上：1)现有观测资料的诊断分析、再分析产品和全球气候模式（GCM）输出；2)陆地-大气相互作用的概念建模，采用基于过程的理想化模型，表示为解析方程，以及大气柱模型耦合到简单的土壤模型（如“桶”模型）。这项活动的一个主要目标是开发可靠的、基于物理的指标，用于量化和比较模式和观测中的日间土壤水分/降水耦合。由于干旱的持续时间和强度对农业产生重大影响，本项目所处理的问题与社会和科学有关。此外，该项目还将支持和培养一名博士后研究员，从而有助于支持和培养下一代科学家。

This project studies the potential feedback between soil moisture and precipitation. A positive feedback would mean that enhanced soil moisture leads to enhanced precipitation, as a wetter surface provides a source of evaporation for subsequent rainfall. In that case, precipitation would lead to wetter soil, which would in turn lead to further precipitation, while a lack of precipitation could lead to a lack of soil moisture and hence further reductions in precipitation leading to prolonged drought. This study assesses the influence of atmospheric and land surface heterogeneity and spatial scale on soil moisture-precipitation coupling, principally at daily timescales, through two interconnected approaches: 1) diagnostic analysis of available observations, reanalysis products, and global climate model (GCM) output; and 2) conceptual modeling of land-atmosphere interactions using process-based idealized models expresed as analytic equations as well as atmospheric column models coupled to simple soil models (eg "bucket" models). A primary objective of this activity is the development of robust, physically-based metrics for quantifying and comparing intraday soil moisture/precipitation coupling in models and observations.The issues addressed in this project have relevance to society as well as science, as drought duration and intensity have substantial consequences for agriculture. In addition, the project will support and train a postdoctoral researcher, thereby helping to support and train the next generation of scientists.