Collaborative Research: The Amazon Groundwater and Its Impact on Evapotranspiration and the Climate of South America

该项目的重点是亚马逊蒸散量（ET）的季节动态，其控制的土地水文，其对区域和大陆降水的后果。它将测试两个假设，（1）亚马逊河下的地下水库可以提高根区土壤水分和旱季ET，（2）这种增强的ET可以影响当地和顺风降水。地下水位观测表明，地下水足够浅，足以影响地表，文献表明，亚马逊ET是区域降水的关键驱动力。这些假设将分两步进行检验。首先，将使用一个地下水-陆地表面综合模型（由罗格斯小组开发的LEAF-Hydro）来模拟观测到的大气场（南美洲陆地数据同化系统）强迫的陆地表面通量。LEAF-Hydro有一个预测地下水耦合到土壤水分与水力再分配（根作为管道，使水向上和向下移动）。将模拟各种过程组合，以隔离更深的模型土壤、更深的根系、水力再分布和地下水的存在的影响。其次，WRF-Hydro将被用作陆地模型来模拟南美洲上空的风场和湿度场，这将被用于使用动态再循环模型（DRM，由亚利桑那州团队开发）追踪蒸汽传输路径。DRM将划定，在空间和时间上，源和汇地区的大陆，因此亚马逊地下水将与气候的continent.The研究评估一个潜在的基本过程在亚马逊水循环：地下水在ET的作用，从而提高我们的理解陆地水存储之间的联系。它也可能对理解世界上最大的雨林在目前和未来森林砍伐和气候变化下的功能产生影响。森林砍伐影响气候的一个机制是深根的丧失，从而减少了ET和降水。这项研究将揭示深根与地下水相互作用的功能。根据预测的未来气候，旱季将更长，一些模型预测亚马逊森林将消亡，通过积极的碳反馈，这可能会加速变暖。提高我们对亚马逊森林如何在旱季生存的理解，将有助于我们了解亚马逊森林未来的发展。

This project focuses on the seasonal dynamics of Amazon evapotranspiration (ET), its control by land hydrology, and its consequences on regional and continental precipitation. It will tests two hypotheses, (1) the groundwater reservoir under the Amazon can enhance root-zone soil moisture and dry-season ET, and (2) this enhanced ET can influence local and downwind precipitation. Water table observations suggest that the groundwater is sufficiently shallow to influence the land surface, and the literature suggest that Amazon ET is a key driver of regional precipitation. These hypotheses will be tested in two steps. First, an integrated groundwater-land surface model (LEAF-Hydro, developed by the Rutgers Team) will be used to simulate land surface fluxes forced by observed atmospheric fields (South American Land Data Assimilation System (SALDAS)). LEAF-Hydro has a prognostic groundwater coupled to the soil moisture with hydraulic redistribution (roots as conduits to move water up and down). Various process combinations will be simulated to isolate the effect of deeper model soil, deeper roots, hydraulic redistribution and the presence of the groundwater. Second, the WRF-Hydro will be used as the land model to simulate the wind and humidity fields over South America, which will be used to trace vapor transport pathways using the Dynamic Recycling Model (DRM, developed by the Arizona Team). DRM will delineate, in space and time, the source and sink regions over the continent, and hence the Amazon groundwater will be linked to the climate of the continent.The research evaluates a potentially fundamental process in the Amazon water cycle: the role of groundwater in ET, and thus improves our understanding of the linkages among terrestrial water stores. It may also have implications to understanding the functions of the world's largest rainforest at the present and in the future under deforestation and climate change. A mechanism whereby deforestation affects the climate is the loss of deep roots and hence a reduced ET and precipitation. This study will shed lights on the functions of deep roots interacting with the groundwater. Under projected future climate with a longer dry season, some models have predicted an Amazon forest die-down, which, via positive carbon feedbacks, may accelerate warming. Improving our understanding of how the Amazon forest survives the dry season today will shed lights on how it may fare in the future.