Rain-formed Fresh Lenses in SPURS-2

热量、淡水和动量从大气层通过海气界面进入海洋，然后通过动力学过程横向和垂直扩散。了解表面动量通量、淡水通量和热通量如何影响上层海洋，对于了解大气和海洋之间的交换至关重要。在热带地区，强降雨在海面上产生了具有浮力的新鲜“透镜体”，可以调节上层海洋的热含量、海流和湍流动能耗散。有必要了解这些新的透镜体是如何形成和衰变的，以便评估它们在海气耦合过程中的作用。该项目将研究这些降雨事件对上层海洋盐度和湍流动能耗散的影响。该研究的新方面包括同时测量该领域的表面和近表面湍流，量化新鲜透镜的横向演变，以及降雨率与表面热结构的关系。该实验将为地表和近地表海洋如何联系提供新的见解，这有可能改善天气和气候模型中耦合海气过程的代表性，特别是在多雨的热带地区。该项目的更广泛影响包括通过旨在吸引社区青年和成年成员参与的实际推广活动，提高公众的科学素养和公众对科学的参与。研究人员还将指导一名研究生和三名不同的本科生，为培养具有全球竞争力的STEM劳动力做出贡献。该项目的主要目标是量化海洋上层雨水形成的淡水异常的时空演变。特别是，其目的是要了解在海气界面的变化和变化之间的关系，在仪表就在表面之下。测量数据将在与美国航天局合作在热带太平洋东部进行的两次实地实验中收集。上大洋区域研究的盐度过程（SPURS-2）项目。拟议实验的组成部分是：（1）用气球上的红外照相机系统跟踪新透镜的水平演变;（2）应用“受控通量技术”，即用二氧化碳激光器加热一小片海面，并计算加热的那片海面冷却的速度，以推断近表面湍流动能耗散;（3）使用安装在拖曳式表面盐度剖面仪上的温度和电导率微结构探针进行湍流耗散的现场测量;（4）利用高速红外照相机观测降雨期间海面热变率的结构。测量将在SPURS-2现场试验期间进行，预计将在2016年和2017年雨季（夏季）举行。观测结果将用于了解海-气界面和海洋最高一米处的湍流耗散之间的关系;量化不同过程在推动新透镜体的形成和衰减方面的作用;推动和验证湍流模型，以评估降雨对整个热带地区上层海洋的影响;探讨降雨率与海洋表层温度结构的关系。该项目的结果有可能大大提高我们对近地表动力学的理解，从而提高它们在耦合模型中的表现力。将该项目的研究结果纳入通用海洋湍流模型还将为将结果外推到其他多雨地区奠定基础，以评估降雨形成的新鲜透镜体在整个热带地区的海气相互作用中的作用。

Heat, freshwater and momentum enter the ocean from the atmosphere through the air-sea interface, and are then dispersed laterally and vertically by dynamical processes. Knowledge of how surface fluxes of momentum, freshwater and heat fluxes affect the upper ocean is critical for understanding the exchanges between the atmosphere and the ocean. In the tropics, heavy rainfall produces buoyant fresh "lenses" at the sea surface that can modulate upper ocean heat content, currents, and turbulent kinetic energy dissipation. It is necessary to understand how these fresh lenses form and decay in order to assess their role in coupled air-sea processes. This project will examine the impacts of these rainfall events on the salinity and turbulent kinetic energy dissipation of the upper ocean. The novel aspects of the research include making simultaneous measurements of surface and near-surface turbulence in the field, quantifying the lateral evolution of fresh lenses, and relating rain rate to surface thermal structure. The experiment will provide new insights into how the surface and near-surface ocean are linked, which has the potential to improve representation of coupled air-sea processes in weather and climate models, particularly in the rainy tropical regions. The broader impacts of the project include increased public scientific literacy and public engagement with science through hands-on outreach activities designed to engage both youth and adult members of the community. The investigators will also mentor a graduate student and three different undergraduate students, contributing to the development of a globally competitive STEM workforce. The primary objective of the project is to quantify the spatial and temporal evolution of rain-formed freshwater anomalies in the upper ocean. In particular, the aim is to understand the relationship between variability at the air-sea interface and variability in the meter just below the surface. Measurements would be collected during two field experiments in the eastern tropical Pacific Ocean in conjunction with NASA?s Salinity Processes in the Upper ocean Regional Study (SPURS-2) project. The components of the proposed experiment are: (1) tracking the horizontal evolution of fresh lenses using a balloon-mounted infrared (IR) camera system;(2) applying the "controlled flux technique", which involves heating a small patch of the sea surface with a carbon dioxide laser and computing the rate at which the heated patch cools, to infer near-surface turbulent kinetic energy dissipation;(3) making in situ measurements of turbulent dissipation using temperature and conductivity microstructure probes mounted on a towed surface salinity profiler; and (4) observing the structure of sea surface thermal variability during rain using a high-speed IR camera.Measurements will be made during the SPURS-2 field experiments, which are expected to take place in the rainy (summer) season of 2016 and 2017. The observations will be used to understand the relationship between turbulent dissipation at the air-sea interface and within the top meter of the ocean; to quantify the role of different processes in driving the build-up and decay of fresh lenses; to force and validate a turbulence model in order to assess the impacts of rainfall on the upper ocean throughout the tropics; and to investigate the relationship between rain rate and the structure of ocean skin temperature. The results from the project have the potential to significantly improve our understanding of near-surface dynamics and hence their representation in coupled models. Integrating the findings from the project into the General Ocean Turbulence Model will also lay the foundation for extrapolating the results to other rainy regions in order to assess the role of rain-formed fresh lenses in air-sea interaction throughout the tropics.