Observing and Modeling the Upper-Troposphere-Lower-Stratosphere Moistening Processes across Scales

虽然与下面的对流层相比，平流层是静止的，但平流层以重要的方式影响着地表的生命（比如阻挡有害的紫外线），每一种影响都依赖于平流层的水蒸气。平流层下层水汽的主要来源是热带地区，那里的海洋表面常年受到太阳的加热，为世界上一些最强烈的风暴提供了燃料。热带雷暴使水蒸气进入对流层上层。在对流层顶冷点（对流层和平流层之间的热边界）没有被冻干的任何水蒸气都可以自由进入平流层，并在全球范围内分布。然而，大多数水蒸气不会立即进入这些风暴上方的平流层，因为这也是对流层顶最冷的地方。此外，最强的风暴不一定发生在最温暖的海洋表面。利用新获得的高分辨率观测和气候模型的层次结构，该项目旨在更好地理解将水蒸气带入平流层所涉及的这些问题。与美国国家大气研究中心（NCAR）的科学家合作，拟议的活动将培训一名研究生，并涉及研究者所在机构的教育项目。这项工作将依赖于最先进的再分析，数值模型的层次结构，以及新的COSMIC-II（星座气象电离层和气候观测系统II）全球定位系统接收器舰队来(1)检查海面温度如何影响对流层冷点顶（CPT）温度，(2)分析大气中决定CPT温度的过程，以及(3)确定CPT温度何时何地对平流层水分吸收最重要。调查小组将首先观察海面温度、CPT温度和水蒸气之间的关系，然后将观察到的关系与模式模拟的关系进行比较。该小组还将利用数值模型来检查分辨率和海面温度异常对CPT温度的影响。除了对气候科学界感兴趣之外，平流层变化的新结果对健康和繁荣以及国防（这是第二次世界大战期间研究平流层湿度和环流的最初动机）都有影响。拟议的活动将支持几个外展项目，包括通过环境变化教育倡议培训印第安纳州K-12教师，以及通过吉姆·霍兰德STEM教育研究倡议招募印第安纳州代表性不足的少数民族学生。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Though quiescent compared to the troposphere below, the stratosphere influences life at the surface in important ways (like blocking harmful UV rays), each dependent on stratospheric water vapor. The primary source of water vapor in the lower stratosphere comes from the tropics, where year-round heating of the ocean surface by the sun fuels some of the world's most intense storms. Tropical thunderstorms loft water vapor into the upper troposphere. Whatever water vapor that is not freeze-dried at the cold point tropopause – the thermal boundary between the troposphere and the stratosphere – is free to enter the stratosphere, where it is distributed globally. However, most water vapor does not enter the stratosphere immediately above these storms, as this is also where the tropopause is coldest. Furthermore, the strongest storms do not necessarily occur over the warmest ocean surface. Leveraging the newly available high-resolution observations and a hierarchy of climate models, this project aims to better understand these issues involved in getting water vapor into the stratosphere. In collaboration with scientists at the National Center for Atmospheric Research (NCAR), the proposed activities will train a graduate student and involve the education programs at the investigator’s institution.This work will rely on state-of-the-art reanalyses, a hierarchy of numerical models, and the new COSMIC-II (Constellation Observing System for Meteorology Ionosphere and Climate II) fleet of global positioning system receivers to (1) examine how sea surface temperatures impact cold point tropopause (CPT) temperatures, (2) analyze the processes in the atmosphere that determine CPT temperature, and (3) determine when and where the CPT temperature matters most for stratospheric moisture uptake. The investigating team will first observe the relationships between sea surface temperature, CPT temperatures, and water vapor, then compare the observed relationships with those in model simulations. The team will also utilize numerical models to examine the impacts of resolution and sea surface temperature anomalies on CPT temperatures. In addition to being of interests to the climate science community, the emerging results on stratospheric change has implications for health and prosperity, as well as national defense (which was the original motivation for the study of stratospheric moisture and circulation during WWII). The proposed activities will support several outreach programs, including the training of K-12 teachers in Indiana through the Educating for Environmental Change initiative, and the recruitment of underrepresented minority students in Indiana through the Jim Holland Research Initiative in STEM Education.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.