Collaborative Research: The Arctic Observing Network - Capturing and Understanding Arctic Change with Renewed Observations at the Davis Strait Gateway

北极和北大西洋之间的海洋淡水和热量交换提供了北极和全球气候相互作用的关键机制。来自河流输入和融化的海冰的北极淡水，通过北极向南流动？网关？从格陵兰岛的西部（戴维斯海峡）和东部（弗拉姆海峡）进入亚极地北大西洋地区，在那里形成了占据深海内部的沃茨。在这些地点，冬季强烈的风暴冷却了上层海洋，使这些沃茨密度足够大，导致它们下沉到深处，有效地将这种大气强迫传递到海洋内部，并推动赤道到极点的热量传输。新鲜的、有浮力的北极流出物降低了这些深水地层区域的表层沃茨密度，因此有可能减缓下沉并调节赤道到极点的热量输送。北极外流的变化也影响到广泛的北大西洋环流模式和拉布拉多海岸的环流，对生态系统产生广泛的影响。相反，向北流动的相对温暖的大西洋沃茨可以提供海洋热量，融化格陵兰冰川，从而加速格陵兰冰帽的融化。海洋热量在加速格陵兰岛融化中的作用的不确定性？在对未来海平面上升的数值预测中，南极冰川是最大的不确定性来源之一。北极-副极地热量和淡水交换的关键作用促使人们重新努力维持戴维斯海峡的持续、持久测量，捕获北极和副极地北大西洋之间的交换（拉布拉多海）在巴芬湾南端的一个阻塞点。该项目将更新戴维斯海峡的综合观测方案，向社区提供数据，并与白令海峡正在进行的收集相匹配，Utqiagvik、阿拉斯加和弗拉姆海峡，以延长主要北极门户的同时测量的时间序列。扩展的时间序列将记录淡水和热通量的变化，并将与数值模拟相结合，以调查控制海峡变化的过程及其潜在影响。主干系统依靠经过测试的系泊设备和传感器的组合，以测量冰的厚度和运动、洋流、温度和盐度，以及两年一次的化学和生物特性船基采样，这些采样在过去十年中成功地提供了核心测量。海底压力传感器增强了该系统，以量化海面高度梯度，这将支持主要强迫机制的调查。综合海洋生态系统观测包括生物地球化学和海洋哺乳动物被动声学测量，并辅以对关键鱼种的跟踪，以及浮游动物和浮游植物观测。这些观测将启动戴维斯海峡/巴芬湾分布式生物观测站（DBO），补充正在开发的大西洋DBO，包括弗拉姆海峡和巴伦支海的样带，以及白令北方现有的太平洋DBO，楚科奇和博福特海。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的支持影响审查标准。

Oceanic freshwater and heat exchange between the Arctic and North Atlantic provide critical mechanisms through which the Arctic and global climate interact. Arctic freshwater, from riverine input and melting sea ice, flows southward through the Arctic ?Gateways? to the west (Davis Strait) and east (Fram Strait) of Greenland into the regions of the subpolar North Atlantic where the waters that occupy the deep ocean interior are formed. At these sites, strong wintertime storms cool the upper ocean, making these waters dense enough to cause them to sink to depth, effectively communicating this atmospheric forcing into the ocean interior and driving the equator-to-pole transport of heat. Fresh, buoyant Arctic outflow reduces the density of surface waters in these deepwater formation regions, and thus has the potential to slow the sinking and modulate equator-to-pole heat transport. Changes in Arctic outflow also impact broad North Atlantic circulation patterns and circulation off the Labrador coast, with wide-ranging impacts to ecosystems. Conversely, the northward flow of relatively warm Atlantic waters can supply oceanic heat to melt Greenlandic glaciers where they encounter the ocean, thus accelerating the melting of Greenland ice cap. Uncertainty surrounding the role of oceanic heat in accelerating the melt of Greenland?s glaciers is one of the largest sources of uncertainty in numerical predictions of future sea level rise. The critical role of Arctic-subpolar heat and freshwater exchange motivates renewed efforts to maintain sustained, persistent, measurements across Davis Strait, capturing exchange between the Arctic and subpolar North Atlantic (Labrador Sea) at a choke point at the southern end of Baffin Bay.This project will renew the integrated observational program at Davis Strait, delivering data to the community and matching ongoing collections at Bering Strait, Utqiagvik, Alaska, and Fram Strait to extend the time series of concurrent measurements across the major Arctic Gateways. The extended timeseries will document changes in freshwater and heat fluxes, and will be combined with numerical modeling to investigate the processes that control variability in the strait and the potential impacts. The backbone system relies on the tested combination of moorings instrumented with sensors to measure ice thickness and motion, ocean currents, temperature and salinity, and biennial ship-based sampling of chemical and biological properties that have successfully delivered core measurements for the past decade. Bottom pressure sensors augment the system to quantify sea surface height gradients, which will support investigations of the primary forcing mechanisms. Integrated marine ecosystem observing includes biogeochemical and marine mammal passive acoustic measurements augmented with tracking of key fish species, and zooplankton and phytoplankton observations. These observations will launch the Davis Strait/Baffin Bay Distributed Biological Observatory (DBO) in Davis Strait, complementing the developing Atlantic DBO that includes transect lines in Fram Strait and Barents Sea, and the existing Pacific DBO in the northern Bering, Chukchi and Beaufort Seas.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.