Rain-formed Fresh Lenses in SPURS-2

SPURS-2 中的雨形成新鲜透镜

• 批准号: 1458759
• 负责人: Kyla Drushka
• 金额: $ 80.01万
• 依托单位: University of Washington
• 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: 2015-03-01 至 2020-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1458759&HistoricalAwards=false
• 关键词: Rain; formed; Fresh; Lenses; SPURS

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.

热量、淡水和动量通过海气界面从大气进入海洋，然后通过动力过程在横向和纵向上分散。了解表面动量通量、淡水通量和热通量如何影响上层海洋，对于理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浮力的新鲜“透镜”，可以调节上层海洋的热含量、洋流和湍流动能耗散。为了评估它们在海气耦合过程中的作用，有必要了解这些新透镜是如何形成和衰变的。本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在野外同时测量地表和近地表湍流，量化新透镜的横向演化，以及将降雨率与地表热结构联系起来。该实验将提供关于地表海洋和近地表海洋是如何联系在一起的新见解，这有可能改善天气和气候模式中海气耦合过程的表现，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人成员的动手推广活动，提高公众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上层海洋雨水形成的淡水异常的时空演变。具体而言，目的是了解海气界面的变化与海面以下一米的变化之间的关系。测量数据将在热带太平洋东部与美国国家航空航天局联合进行的两次实地实验中收集。美国海洋上层盐度过程区域研究（sprs -2）项目。实验的组成包括：(1)利用气球红外相机系统跟踪新鲜镜头的水平演化；(2)应用“可控通量技术”，用二氧化碳激光加热一小块海面，并计算被加热的一小块海面的冷却速率，以推断近地表湍流动能耗散；(3)利用安装在拖曳式海面盐度剖面仪上的温度和电导率微结构探头对湍流耗散进行现场测量；(4)利用高速红外相机观测降雨期间海面热变结构。测量将在sprs -2现场实验期间进行，预计将在2016年和2017年的多雨（夏季）季节进行。这些观测将用于了解海气界面和海洋顶部一米内的湍流耗散之间的关系；量化不同过程在驱动新晶状体形成和衰变中的作用；强迫和验证湍流模式，以评估整个热带地区的降雨对上层海洋的影响；并探讨了降雨率与海洋表面温度结构的关系。该项目的结果有可能显著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示。将该项目的发现整合到一般海洋湍流模型中，也将为将结果外推到其他多雨地区奠定基础，以便评估雨形成的新鲜透镜在整个热带地区的海气相互作用中的作用。