Collaborative Research: An Optimality Principle of Evaporation over the Land Surface

本研究的工作假设是，在特定环境中给定的辐射能量输入，地球-大气界面的蒸发总是最大的。在该假设下，蒸发是根据给定能量输入的地表温度、地表土壤湿度和感热通量（湍流输送的一种度量）进行优化的结果而唯一确定的。知识价值：这里提出的想法将允许模型的独立验证，将导致改善地表水文的参数化，更重要的是，将提供一个框架，在这个框架中，土地蒸发对辐射变化的敏感性，地球表面性质等可以独立于传统的经验模型进行评估。研究策略包括：1。进一步的理论和实证研究，包括长波辐射对地表温度的依赖；2. 显示蒸发对大气湿度缺乏敏感性；3. 进行实地工作，用更适当的数据集在裸露的土壤上测试这些概念；4. 考察现有蒸发模型的有效性；5. 开始将概念扩展到植被表面。更广泛的影响：这项工作代表了具有理论和实验专业知识的水文学家和生态学家之间广泛的跨学科合作。这项工作支持了爱荷华大学独特的实验基础设施。本科生将有机会做理论和实地工作。几名研究生将根据他们在本提案中的工作获得硕士/博士学位。所有学生都将被鼓励并资助在专业会议上展示研究成果。所有作品将及时在评审文献中发表。这项提案是在新的麻省理工学院地球系统倡议的保护下提交的。这项研究和教育工作旨在促进对“地球身体”的理解，以便定义适当的科学来制定健全的可持续性政策。首席研究员是该计划的领导者之一，也是执行委员会的成员，并教授该计划新生核心替代项目的必修课程之一：Terrascope。

Bras0309594The working hypothesis of this research is that evaporation at the earth-atmosphere interface is always maximized, given radiative energy input in a particular environment. Under the hypothesis, evaporation is uniquely determined as a result of an optimization exercise in terms of surface temperature, surface soil moisture and sensible heat flux (a measure of turbulent transport) given an energy input.Intellectual Merits:The ideas presented here will allow the independent verification of models, will lead to improved parameterization of surface hydrology and, more importantly, will provide a framework in which the sensitivity of land evaporation to changes in radiation, earth surface properties etc. could be evaluated independently of the traditional empirical models. The research strategy includes: 1. further theoretical and empirical study to include the dependence of long wave radiation on surface temperature; 2. show the lack of sensitivity of evaporation to atmospheric moisture; 3. carry out field work to test the concepts with more appropriate data sets over bare soils; 4. investigate the validity of existing evaporation models; 5. initiate the extension of the concepts to vegetated surfaces.Broader Impacts:This work represents a broad interdisciplinary collaboration between hydrologists and ecologists with theoretical and experimental expertise. The work supports unique experimental infrastructure at the University of Iowa. Undergraduate students will have the opportunities to do theoretical and field work. Several graduate students will get their masters/doctoral degrees based on their work in this proposal. All students will be encouraged and financed to present findings in professional meetings. All work will be published in the refereed literature in a timely manner. This proposal is being submitted under the umbrella of the new MIT Earth System Initiative. This research and educational effort is intended to promote the understanding of the ``body earth'' in order to define the appropriate science to develop sound sustainability policies. The Principal Investigator is one of the leaders of this initiative, a member of its executive council, and teaches one of the require courses under the initiative's freshman core alternative program: Terrascope.