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与全球气候相互作用的重要机制。来自河流输入和融化的海冰的北极淡水向南流经北极的门户？格陵兰以西(戴维斯海峡)和以东(弗拉姆海峡)进入亚极地北大西洋地区，那里形成了占据深海内陆的水域。在这些地点，强大的冬季风暴冷却了上层海洋，使这些水域的密度足够高，导致它们沉入深处，有效地传达了这种强迫进入海洋内部的大气，并推动了热量从赤道到极地的传输。新鲜的、漂浮的北极外流降低了这些深水形成区域的地表水密度，因此有可能减缓下沉并调节赤道到极地的热量输送。北极外流的变化也影响到北大西洋的环流模式和拉布拉多沿岸的环流，对生态系统产生广泛的影响。相反，相对温暖的大西洋海水向北流动可以提供海洋热量，使格陵兰冰川在与海洋相遇的地方融化，从而加速格陵兰冰盖的融化。围绕海洋热在加速格陵兰融化中的作用的不确定性？S冰川是未来海平面上升数字预测中最大的不确定性来源之一。北极-亚极热量和淡水交换的关键作用促使人们重新努力，在戴维斯海峡保持持续、持久的测量，捕捉北极和亚极北大西洋(拉布拉多海)之间的交换，地点位于巴芬湾南端的一个瓶颈。该项目将更新戴维斯海峡的综合观测计划，向社区提供数据，并匹配白令海峡、乌恰格维克、阿拉斯加和弗拉姆海峡的正在进行的收集，以延长主要北极门户的同步测量的时间序列。延长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。主干系统依赖于经过测试的系泊设备组合，这些系泊设备配有传感器以测量冰的厚度和运动、洋流、温度和盐度，以及过去十年成功提供核心测量的两年一次的船舶化学和生物特性采样。海底压力传感器增强了系统，以量化海面高度梯度，这将支持对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以及浮游动物和浮游植物观测。这些观测将在戴维斯海峡启动戴维斯海峡/巴芬湾分布式生物观测站(DBO)，以补充正在开发的大西洋DBO，其中包括弗拉姆海峡和巴伦支海的横断线，以及白令海、楚科奇和波弗特海北部的现有太平洋DBO。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.