CAREER: Hydroclimatic Response to Natural and Anthropogenic Land Cover Change over South America: A Focus on the La Plata River Basin

职业：南美洲自然和人为土地覆盖变化的水文气候响应：聚焦拉普拉塔河流域

• 批准号: 1454089
• 负责人: Francina Dominguez
• 金额: $ 57.41万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1454089&HistoricalAwards=false
• 关键词: CAREER; Hydroclimatic; Response; Natural; Anthropogenic

This research is an effort to understand the influence of land cover change on the hydroclimatology of the La Plata River Basin (LPRB). The LPRB is the second largest hydrological basin in South America after the Amazon, at about a third the size of the continental US. The weather and climate of the region is dominated by the South American monsoon system (SAMS), in which summer (December to February) rains are fed by moisture which enters the continent in the equatorial trade winds, crosses the Amazon, and is transported to the LPRB by the South American low level jet. Over the course of this route the moisture can fall as rain and be returned to the atmosphere through evapotranspiration multiple times, a process referred to as moisture recycling. Previous work by the PI and others suggests that 60 to 70 percent of the mean annual precipitation over the LPRB comes from evapotranspiration from the South American landmass, with about 24 percent coming from local evapotranspiration over the LPRB. Since the land surface is an important source of moisture for precipitation, soil moisture anomalies can become persistent as they lead to further reductions in precipitation. In addition, land surface conditions can affect precipitation through their influence on the thermodynamic structure of the lower atmosphere, which can modulate atmospheric circulation and stability. The key role of land-atmosphere coupling in the LPRB suggests that changes in land cover could have significant impacts on the local hydroclimate. The PI notes that there has been intensive deforestation in the region, with perhaps the highest deforestation rate in the world for the period 2000 to 2012, thus it is of interest to understand how deforestation is affecting the monsoon system in the region. More specifically, the PI seeks to understand the relative impacts of moisture recycling and thermodynamic/dynamic land-atmosphere feedbacks on South American precipitation patterns. One hypothesis to be pursued is that the strongest land-atmosphere interactions occur during the late spring and early summer season in association with the SAMS, with a spatial pattern that highlights the transition regions linking the tropics and subtropics. Another is that the thermodynamic/dynamic effects are more important than changes in precipitation recycling in determining the interannual variability of LPRB precipitation. But the PI also hypothesizes that projected future deforestation in South America would change the relative importance of moisture recycling and thermodynamic/dynamic effects, and the shift would be accompanied by significant reductions in LPRB precipitation. The research will also examine the extent to which deforestation changes the frequency and intensity of precipitation. In addition, the project will consider how these feedbacks may change under projected future changes in land surface conditions.The research agenda is built around three tools, a statistical approach known as the generalized equilibrium feedback assessment (GEFA) and two enhanced versions of the Weather and Research Forecast (WRF) model. The statistical method is a multivariate lagged regression technique developed to quantify feedback strength, which can be used to determine the strength of moisture recycling on a spatially varying basis. One version of the WRF model (WRF-WVT, previously developed by the PI) has been augmented to include tracers used to track water vapor transport, and this configuration can be used to determine the source regions of water vapor and hence the contributions of transport and local evaporation to precipitation. The model has also been modified to use ecosystem functional types (EFTs) which can be adjusted to represent forested and agricultural land, and the model is able to simulate the mesoscale convective systems which account for much of the rainfall in the LPRB. The other version of WRF is WRF-hydro, a community model which represents the subsurface component of the hydrological cycle, which the PI claims is " particularly important over South America, as ground- water dynamics can completely change the atmospheric fluxes".The research is accompanied by an education effort in which three new courses would be developed to give students a thorough grounding in hydroclimatology One course focuses on hydrometeorological observations, and will give selected students an opportunity to perform fieldwork during a 2-week period in the summer. The fieldwork program is developed in partnership with the Center for Western Weather and Water Extremes (CW3E) at the Scripps Istitute of Oceanography. For the period 2015-2018 students will participate in the Calwater2 field campaign to observe atmospheric rivers, taking measurements of precipitation, stream flow, and soil moisture. A second course introduces students to numerical modeling using the WRF-hydro model, and in this class selected students travel to the National Center for Atmospheric Research during the summer to participate in model development. A third course is developed to teach basic hydrology to students with an atmospheric science background. This course replaces traditional hydrology courses, in which the subject is taught from an atmospheric science perspective. The course is intended as an alternative to typical hydrology courses in which the focus is on issues relating to the construction and operation of waterworks. The course attempts to develop a unified language for the description of surface and subsurface processes, which is analogous to the conceptual framework used for atmospheric processes and helps students to work with models which incorporate atmosphere, surface, and subsurface components.

本研究旨在了解土地覆被变化对拉普拉塔河流域水文气候学的影响。 LPRB是南美洲仅次于亚马逊河的第二大水文流域，约为美国大陆的三分之一。 该地区的天气和气候主要受南美季风系统（SAMS）控制，夏季（12月至次年2月）的降雨由赤道信风中进入大陆的水分提供，穿过亚马逊河，并由南美低空急流输送到LPRB。 在这条路线的过程中，水分可以降雨，并通过多次蒸散返回大气，这一过程被称为水分再循环。 PI和其他人以前的工作表明，LPRB上的年平均降水量的60%到70%来自南美大陆的蒸散，大约24%来自LPRB上的当地蒸散。 由于地表是降水的重要水分来源，土壤水分异常可能会持续下去，因为它们会导致降水进一步减少。 此外，陆面条件可以通过影响低层大气的热力结构来影响降水，而低层大气的热力结构可以调节大气环流和稳定性。 陆-气耦合在LPRB中的关键作用表明，土地覆盖的变化可能对当地水文气候产生重大影响。 PI指出，该地区的森林砍伐严重，2000年至2012年期间的森林砍伐率可能是世界上最高的，因此了解森林砍伐如何影响该地区的季风系统很有意义。 更具体地说，PI旨在了解水分再循环和热力学/动力学陆-气反馈对南美降水模式的相对影响。 要追求的一个假设是，最强的陆-气相互作用发生在春末夏初季节与SAMS，与空间格局，突出了连接热带和亚热带的过渡区域。 另一个是热力学/动力学效应比降水再循环的变化在决定LPRB降水的年际变化方面更重要。 但PI还假设，预计未来在南美洲的森林砍伐将改变水分循环和热力学/动力学效应的相对重要性，这种转变将伴随着LPRB降水的显着减少。 这项研究还将研究森林砍伐在多大程度上改变了降水的频率和强度。 此外，该项目还将考虑这些反馈在预计的未来地表条件变化下可能如何变化，研究议程围绕三个工具建立，一个被称为广义平衡反馈评估（GEFA）的统计方法和两个增强版的天气和研究预报（WRF）模型。 统计方法是一种多元滞后回归技术，用于量化反馈强度，可用于确定空间变化基础上的水分循环强度。 WRF模式的一个版本（WRF-WVT，以前由PI开发）已被增强，包括用于跟踪水汽输送的示踪剂，这种配置可用于确定水汽的源区，从而确定输送和局部蒸发对降水的贡献。 该模型也被修改，使用生态系统功能类型（EFT），可以调整，以代表森林和农业用地，该模型能够模拟中尺度对流系统，占大部分的降雨在LPRB。 WRF的另一个版本是WRF-hydro，这是一个代表水文循环地下部分的社区模型，PI声称这对南美洲特别重要，因为地下水动力学可以完全改变大气通量”。这项研究的同时，还将开展一项教育工作，其中将开发三门新课程，使学生在水文气候学方面有一个全面的基础。水文气象观测，并将让选定的学生有机会在夏季进行为期两周的实地考察。 该实地考察计划是与斯克里普斯海洋研究所的西部天气和水极端事件中心（CW 3E）合作开发的。 在2015-2018年期间，学生将参加Calwater 2实地活动，观察大气河流，测量降水，水流和土壤湿度。 第二门课程向学生介绍使用WRF水力模型进行数值建模，在这门课程中，选定的学生将在夏季前往国家大气研究中心参加模型开发。 第三门课程是向具有大气科学背景的学生讲授基础水文学。 本课程取代传统的水文学课程，其中该主题是从大气科学的角度来教授。 该课程旨在作为典型水文课程的替代方案，重点是与水利工程的建设和运营有关的问题。 该课程试图开发一种统一的语言来描述地表和地下过程，这类似于用于大气过程的概念框架，并帮助学生使用包含大气，地表和地下组件的模型。

项目成果

Impacts of a Groundwater Scheme on Hydroclimatological Conditions over Southern South America

• DOI: 10.1175/jhm-d-16-0052.1
• 发表时间: 2016-11
• 期刊: Journal of Hydrometeorology
• 影响因子: 3.8
• 作者: J. A. Martínez;F. Dominguez;G. Miguez-Macho

Effects of a groundwater scheme on the simulation of soil moisture and evapotranspiration over southern South America

• DOI: 10.1175/jhm-d-16-0051.1
• 发表时间: 2016-11
• 期刊: Journal of Hydrometeorology
• 影响因子: 3.8
• 作者: J. A. Martinez;F. Dominguez;G. Miguez-Macho