Measurements of Air-Sea Gas Transfer and Bubble Dynamics in the Southern Ocean during a SOLAS Dual Tracer Experiment

在本项目中，哥伦比亚大学Lamont-Dougherty地球观测站（LDEO）的研究人员将参与由新西兰科学团队领导的国际SOLAS （Surface Ocean Lower Atmosphere Study）双示踪气体交换研究。这项研究旨在提高我们对南大洋气体交换及其对风速和其他因素的依赖的认识，南大洋是大气二氧化碳海气交换的关键区域。气体传递速度(k)与风速的参数化并不理想，因为还有其他因素会影响k。然而，许多研究人员依靠这些参数化来推导气体传递速度，因此继续改进k与风速（或平均方波斜率）关系的参数化对于提高对全球生物地球化学收支的理解至关重要，包括二氧化碳的收支。在实验期间，LDEO团队将为双示踪实验（3He/SF6）提供3He数据（约300个测量值），该实验将提供大约20天时间内和大约250平方公里区域内的空间和时间平均k。在本实验中，将3He和SF6的混合物在46.67 S， 178.5 E处注入表面混合层，并对所得到的示踪斑块进行约20天的调查。k可以由贴片中心附近的3He/SF6比值的下降速率得出。根据实验期间的风况，研究小组应该能够在大约2到14米/秒的风速范围内获得4到8个k值。这些数据将用于测试从全球海洋14C清单得出的气体交换参数化，以及在沿海和大陆架地区进行的双示踪气体交换实验结果的支持，是否可以外推到南方高纬度地区。双示踪结果将由基于微气象测量的短时间尺度、小空间尺度的k测量（CO2的涡旋相关，以及CO2和DMS的松弛涡旋积累测量）加以补充。除了双示踪剂测量外，该团队还将进行Ne， N2， O2和Ar测量（与罗德岛大学和普林斯顿大学的同事合作），以更好地了解气泡在高风速下气体交换中的作用。综上所述，这些数据将提高我们对南大洋数据稀疏区域的k值的认识，并大大有助于弥补我们对海气通量认识的一个关键空白，从而解决SOLAS科学计划的一个关键要素。

ABSTRACTOCE-0327779In this project, researchers at the Lamont-Dougherty Earth Observatory (LDEO) of Columbia University will participate in an international SOLAS (Surface Ocean Lower Atmosphere Study) dual tracer gas exchange study led by a New Zealand scientific team. The study aims at improving our understanding of gas exchange and their dependence on wind speed and other factors in the Southern Ocean, a key region for air-sea exchange of atmospheric CO2. Parameterization of gas transfer velocity (k) with wind speed is not ideal, as there are other factors that contribute to influence k. However, many investigators rely on these parameterizations to derive gas transfer velocities so continuing to improve the parameterization of k versus wind speed (or mean square wave slope) relationships is critical for improving understanding of global biogeochemical budgets, including that of CO2.During the experiment, the LDEO team will contribute the 3He data (ca. 300 measurements) to a dual tracer experiment (3He/SF6) that will provide spatially and temporally averaged k over a period of ca. 20 days and a region of ca. 250 km2. For this experiment, a mixture of 3He and SF6 will be injected into the surface mixed layer at 46.67 'S, 178.5 'E, and the resulting tracer patch will be surveyed for ca. 20 days. k can be derived from the rate of decrease in the 3He/SF6 ratio close to the center of the patch. Depending on the wind regime during the experiment, the team should be able to obtain 4 to 8 estimates of k over a range of wind speeds between ca. 2 and 14 m s-1. These data will be used to test how well gas exchange parameterizations, derived from global ocean 14C inventories and supported by results from dual tracer gas exchange experiments conducted in coastal and shelf area, can be extrapolated to higher southern latitudes. The dual tracer results will be complemented by short time scale, small spatial scale measurements of k that are based on micrometeorological measurements (eddy correlation of CO2, and relaxed eddy accumulation measurements of CO2 and DMS). In addition to the dual tracer measurements, the team will perform Ne, N2, O2 and Ar measurements (in collaboration with colleagues at the University of Rhode Island and Princeton University) to understand better the role of bubbles in gas exchange at high wind speeds. Taken together, these data should improve our knowledge of k in the data-sparse regions in the Southern Ocean and significantly contribute to closing a critical gap in our knowledge of air-sea gas fluxes, thereby addressing a key element of the SOLAS science plan.