Atmospheric Lakes of Vapor Drifting Over the East Coast of Africa

作为长期存在和孤立的潮湿气团，“大气湖”被观测到在从广阔的印度-太平洋暖池上方的广大潮湿空气中分离出来后，缓慢地漂过赤道西印度洋。这些湖泊孕育了大量的深层对流，它们的登陆为干旱的东非海岸带来了急需的雨水。迄今为止，人们对这些湖泊知之甚少，而关于它们的新知识可能有助于管理当地水资源，并改善天气气象学研究较少的地区的天气预报。通过使用全球再分析数据、观测以及业务预报和气候模式的输出，这项工作旨在通过检查涉及对流、动力学、湍流和辐射密切耦合的控制过程来了解这些湖泊。这项工作将培养一名研究生。作为潮湿热带大气的天然实验室，大气湖泊可能是地球上最接近对流自聚集的类似物，对流自聚集是一种需要观测试金石的热带气候的当代研究范式。在假设的指导下，研究人员将编制水蒸气和密切相关的（但更容易解释的）湿静态能的湖泊跟踪预算。MERRA-2再分析为封闭预算提供了所有条件，包括表明模型过程缺点的分析趋势。独立测量的卫星图像将用于描述云场的特征，包括对流系统的潜在聚集。由此产生的湖泊维持和繁殖过程的定量描述将成为该项目对天气预报和气候模拟模型数据进行比较研究的目标和挑战。登陆时的新进程也将被仔细检查，因为它们通过降雨影响东非及其人民。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。

As long-lived and isolated moist air masses, “atmospheric lakes” are observed to drift slowly across the western equatorial Indian Ocean after pinching off from the vast area of moist air over the broad Indo-Pacific warm pool. These lakes nurture clusters of precipitating deep convection, and their landfalls produce much-needed rain over the generally dry eastern African coast. To date, very little is known about these lakes, and new knowledge about them may help manage local water resource and improve weather forecasting over a region where synoptic meteorology is little studied. By using global reanalysis data, observations, and outputs from operational forecast and climate models, the work aims to understand these lakes by examining their governing processes that involve the intimately coupling of convection, dynamics, turbulence, and radiation. The work will train a graduate student.As natural laboratories of moist tropical atmosphere, atmospheric lakes may be Earth’s closest analogues to convective self-aggregation, a much-studied contemporary paradigm of tropical climate in need of observational touchstones. Guided by hypotheses, the investigators will compile lake-following budgets of water vapor and of the closely related (but more richly interpretable) moist static energy. The MERRA-2 reanalysis offers all terms for closed budgets, including analysis tendencies indicative of model process shortcomings. Independently measured satellite imagery will be used to characterize the cloud field, including the potential aggregation of convective systems. The resulting quantitative depiction of the lakes’ maintenance and propagation processes will serve as a target and challenge to the project’s comparative studies of weather-forecast and climate-simulation model data. New processes which come in at landfall will also be examined carefully, as they impact eastern Africa and its people through rainfall.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.