Radon-222/Radium-226 profiles Beaurfort Sea

We present 34 profiles of radon-deficit from the ice-ocean boundary layer of the Beaufort Sea. Including these 34, there are presently 58 published radon-deficit estimates of k, the air-sea gas transfer velocity in the Arctic Ocean; 52 of these estimates were derived from water covered by 10% sea ice or more. The average value of K collected since 2011 is 4.0 +- 1.2 m d-1 This exceeds the quadratic wind speed prediction of weighted kws = 2.85 m d-1 with mean weighted wind speed of 6.4 m s-1. We show how ice cover changes the mixed-layer radon budget, and yields an “effective gas transfer velocity”. We use these 58 estimates to statistically evaluate the suitability of a wind speed parameterization for k, when the ocean surface is ice covered. Whereas the six profiles taken from the open ocean indicate a statistically good fit to wind speed parameterizations, the same parameterizations could not reproduce k from the sea ice zone. We conclude that techniques for estimating k in the open ocean cannot be similarly applied to determine k in the presence of sea ice. The magnitude of k through gaps in the ice may reach high values as ice cover increases, possibly as a result of focused turbulence dissipation at openings in the free surface. These 58 profiles are presently the most complete set of estimates of k across seasons and variable ice cover; as dissolved tracer budgets, they reflect air-sea gas exchange with no impact from air-ice gas exchange.本研究提供了波弗特海（Beaufort Sea）冰-海洋边界层中34组氡亏损（radon-deficit）剖面数据。连同这34组数据，目前已公开的北冰洋海-气气体传输速率（air-sea gas transfer velocity）k的氡亏损估算值共计58组，其中52组的估算数据源自海冰覆盖率达10%及以上的海域。2011年以来收集的k平均值为4.0±1.2 m·d⁻¹，该值高于加权风速二次拟合预测值：当加权平均风速为6.4 m·s⁻¹时，预测的加权传输速率k_ws为2.85 m·d⁻¹。本研究阐明了海冰覆盖如何改变海洋混合层的氡收支，并由此得到"有效气体传输速率"。我们利用这58组估算数据，针对冰覆盖洋面场景下k的风速参数化（wind speed parameterization）方案适用性开展了统计学评估。尽管从开阔大洋获取的6组剖面数据与风速参数化方案呈现出统计学意义上的良好拟合效果，但同一套参数化方案却无法复演海冰覆盖海域的k值。据此我们认为，开阔大洋的k值估算方法无法直接类推应用于存在海冰覆盖的海域。随着海冰覆盖率提升，冰间水道区域的k值可达到较高水平，这可能源于自由表面开口处的湍流耗散被集中强化。目前这58组剖面数据是涵盖不同季节与可变海冰覆盖情况的最完整k值估算数据集；作为溶解示踪剂收支数据，它们反映的海-气气体交换过程不受冰-气气体交换的影响。