Voelker Georg S, Olbers Dirk, Walter Maren, Mertens Christian, Myers Paul G
MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany.
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
Ocean Dyn. 2020;70(11):1357-1376. doi: 10.1007/s10236-020-01388-y. Epub 2020 Sep 9.
Energy transfer mechanisms between the atmosphere and the deep ocean have been studied for many years. Their importance to the ocean's energy balance and possible implications on mixing are widely accepted. The slab model by Pollard (Deep-Sea Res Oceanogr Abstr 17(4):795-812, 1970) is a well-established simulation of near-inertial motion and energy inferred through wind-ocean interaction. Such a model is set up with hourly wind forcing from the NCEP-CFSR reanalysis that allows computations up to high latitudes without loss of resonance. Augmenting the one-dimensional model with the horizontal divergence of the near-inertial current field leads to direct estimates of energy transfer spectra of internal wave radiation from the mixed layer base into the ocean interior. Calculations using this hybrid model are carried out for the North Atlantic during the years 1989 and 1996, which are associated with positive and negative North Atlantic Oscillation index, respectively. Results indicate a range of meridional regimes with distinct energy transfer ratios. These are interpreted in terms of the mixed layer depth, the buoyancy frequency at the mixed layer base, and the wind field structure. The average ratio of radiated energy fluxes from the mixed layer to near-inertial wind power for both years is approximately 12%. The dependence on the wind structure is supported by simulations of idealized wind stress fronts with variable width and translation speeds.
大气与深海之间的能量传递机制已经研究多年。它们对海洋能量平衡的重要性以及对混合的潜在影响已被广泛认可。波拉德（Pollard）的平板模型（《深海研究海洋学文摘》17(4):795 - 812，1970年）是通过风 - 海相互作用对近惯性运动和能量进行的一种成熟模拟。该模型根据美国国家环境预测中心气候预报系统再分析（NCEP - CFSR）每小时的风强迫数据建立，能够在不失共振的情况下计算到高纬度地区。用近惯性流场的水平散度增强一维模型，可直接估算从混合层底部到海洋内部的内波辐射能量传递谱。利用这个混合模型对1989年和1996年的北大西洋进行了计算，这两年分别与北大西洋涛动指数的正值和负值相关。结果表明存在一系列具有不同能量传递比率的经向区域。这些区域可根据混合层深度、混合层底部的浮力频率以及风场结构来解释。这两年从混合层辐射出的能量通量与近惯性风能的平均比率约为12%。对理想化风应力锋面不同宽度和移动速度的模拟结果支持了能量传递对风结构的依赖性。
