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

合作研究：亚马逊地下水及其对南美洲蒸散和气候的影响

• 批准号: 1045110
• 负责人: Ying Fan Reinfelder
• 金额: $ 30.77万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1045110&HistoricalAwards=false
• 关键词: Collaborative; Research; Amazon; Groundwater; Its

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.

该项目重点研究亚马逊蒸散量 (ET) 的季节性动态、陆地水文学对其的控制及其对区域和大陆降水的影响。它将检验两个假设：（1）亚马逊河下的地下水库可以增强根区土壤湿度和旱季蒸散，（2）这种增强的蒸散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因素。这些假设将分两步进行检验。首先，综合地下水-地表模型（LEAF-Hydro，由罗格斯大学团队开发）将用于模拟观测到的大气场（南美陆地数据同化系统（SALDAS））所强制的地表通量。 LEAF-Hydro 通过水力重新分配将预测地下水与土壤湿度相结合（根作为上下移动水的管道）。将模拟各种过程组合，以隔离更深的模型土壤、更深的根系、水力重新分配和地下水存在的影响。其次，WRF-Hydro 将用作陆地模型来模拟南美上空的风场和湿度场，该模型将用于使用动态回收模型（DRM，由亚利桑那团队开发）追踪蒸汽传输路径。 DRM 将在空间和时间上描绘整个大陆的源区和汇区，因此亚马逊地下水将与该大陆的气候联系起来。该研究评估了亚马逊水循环中的一个潜在基本过程：地下水在 ET 中的作用，从而提高了我们对陆地水储存之间联系的理解。它还可能对了解世界上最大的热带雨林目前和未来在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，从而减少蒸散和降水。这项研究将揭示深根与地下水相互作用的功能。根据预计未来旱季更长的气候，一些模型预测亚马逊森林将消失，通过正碳反馈，这可能会加速变暖。加深我们对亚马逊森林如何在今天的旱季生存的了解，将有助于了解它未来的表现。