Spring Soil Temperature Anomalies in the Western United States and Summer Droughts in the Southern Plains

美国西部春季土壤温度异常和南部平原夏季干旱

• 批准号: 1346813
• 负责人: Yongkang Xue
• 金额: $ 55万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1346813&HistoricalAwards=false
• 关键词: Spring; Soil; Temperature; Anomalies; Western

This project seeks to understand the causes of precipitation variability in the US Southern Plains (roughly equivalent to Nebraska, Missouri, Oklahoma, Arkansas, Texas, and Louisiana). This area is among the most drought-prone in the US, and droughts in the region have substantial economic impacts. This project examines the hypothesis that Spring subsurface soil temperature anomalies in the Western US in produce rainfall changes in the Southern Plains in the subsequent summer. The hypothesized relationship is such that warm subsurface soil temperature in the West, through its manifestation in warm land surface temperature, generates a cyclonic circulation in the overlying atmosphere, which propagates eastward to produce enhanced June rainfall to the east and south of the soil temperature anomaly, with the opposite result (i.e. drought) for cold subsurface soil temperature. A further issue to be examined in the project is the effect of frozen soil on the precipitation response to soil temperature. The project tests the extent to which a better representation of frozen soil in regional climate models (RCMs) can lead to a stronger relationship between Western soil temperature and Southern Plains precipitation simulated by the model. Preliminary work for the proposal has shown evidence for the effect of subsurface soil temperature, and work performed under the project will follow up with a set of model simulation experiments. The experiments will be conducted with a model configuration in which a global atmospheric model (the NOAA/NCEP Global Forecast System model, or GFS) will be combined with an RCM known as the Weather Research and Forecasting (WRF) model, in which land surface processes are simulated by the Simplified Simple Biosphere (SSiB) model. Experiments typically use imposed sea surface temperatures and sea ice to produce a global simulation for a particular year using the GFS model, which is in turn used to specify lateral boundary conditions for WRF simulations. The experiments test the influence of all local and remote effects on Southern Plains precipitation, including soil conditions in the Western states and also sea surface temperature (SST) fluctuations. SSTs, including those associated with El Nino can affect Southern Plains precipitation both directly and indirectly, through their influence on soil temperature to the West.The work has broader impacts due to the economic and societal impact of drought in the Southern Plains and the desirability of better methods to predict the extent and duration of droughts. The project will also support a post-doctoral researcher, thereby supporting the next generation of scientists in this research area.

该项目旨在了解美国南部平原降水变异性的原因（大致相当于内布拉斯加州，密苏里州，俄克拉荷马州，阿肯色州，德克萨斯州和路易斯安那州）。 该地区是美国最容易干旱的地区之一，该地区的干旱具有重大的经济影响。 该项目研究了以下假设：美国西部的春季地下土壤温度异常在随后的夏季在南部平原的降雨变化。假设的关系是使西方温暖的地下土壤温度通过温暖的土地表面温度的表现产生了在上覆的大气中的气旋循环，向东传播，从而使土壤温度异常的东部和南部降雨增强，结果相反的结果（即干旱），以至于低地下土壤温度。该项目中要研究的另一个问题是冷冻土壤对降水对土壤温度的反应的影响。 该项目测试在区域气候模型（RCMS）中更好地表示冷冻土壤的程度可以导致西方土壤温度与模型模拟的南部平原降水之间的更强关系。 该提案的初步工作显示了地下土壤温度的影响的证据，并且在项目下进行的工作将进行一组模型模拟实验。实验将采用模型配置进行，在该模型配置中，全球大气模型（NOAA/NCEP全局预测系统模型或GFS）将与称为天气研究和预测（WRF）模型的RCM相结合，其中由简化的简单生物圈（SSIB）模型模拟​​了土地表面过程。 实验通常使用施加的海面温度和海冰使用GFS模型为特定年份产生全局模拟，而GFS模型又用于指定WRF模拟的横向边界条件。 该实验测试了所有局部和远程影响对南部平原降水的影响，包括西方州的土壤条件以及海面温度（SST）波动。 SST，包括与El Nino相关的SST可以通过对西部土壤温度的影响直接和间接影响南部平原的降水。由于干旱对南部平原的经济和社会影响，这项工作对南部平原的经济和社会影响产生了更大的影响，并且可以更好地预测干旱的方法，以预测干旱的程度和持续时间。该项目还将支持博士后研究人员，从而支持该研究领域的下一代科学家。