Wang Yuanqi, Feng Zhixuan, Lin Peigen, Song Hongjun, Zhang Jicai, Wu Hui, Jin Haiyan, Chen Jianfang, Qi Di, Grebmeier Jacqueline M
State Key Laboratory of Estuarine and Coastal Research, School of Marine Sciences, and Institute of Eco-Chongming, East China Normal University, Shanghai, China.
State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China.
Nat Commun. 2024 Nov 29;15(1):10389. doi: 10.1038/s41467-024-54733-w.
The Arctic Ocean has experienced significant sea ice loss over recent decades, shifting towards a thinner and more mobile seasonal ice regime. However, the impacts of these transformations on the upper ocean dynamics of the biologically productive Pacific Arctic continental shelves remain underexplored. Here, we quantified the summer upper mixed layer depth and analyzed its interannual to decadal evolution with sea ice and atmospheric forcing, using hydrographic observations and model reanalysis from 1996 to 2021. Before 2006, a shoaling summer mixed layer was associated with sea ice loss and surface warming. After 2007, however, the upper mixed layer reversed to a generally deepening trend due to markedly lengthened open water duration, enhanced wind-induced mixing, and reduced ice meltwater input. Our findings reveal a shift in the primary drivers of upper ocean dynamics, with surface buoyancy flux dominant initially, followed by a shift to wind forcing despite continued sea ice decline. These changes in upper ocean structure and forcing mechanisms may have substantial implications for the marine ecosystem, potentially contributing to unusual fall phytoplankton blooms and intensified ocean acidification observed in the past decade.
近几十年来，北冰洋的海冰显著减少，正朝着更薄、更易移动的季节性冰情转变。然而，这些变化对生物生产力较高的太平洋北极大陆架上层海洋动力学的影响仍未得到充分研究。在此，我们利用1996年至2021年的水文观测和模型再分析数据，量化了夏季上层混合层深度，并分析了其与海冰和大气强迫相关的年际到年代际演变。2006年之前，夏季混合层变浅与海冰流失和表面变暖有关。然而，2007年之后，由于开阔水域持续时间显著延长、风致混合增强以及冰融水输入减少，上层混合层转而呈现总体加深的趋势。我们的研究结果揭示了上层海洋动力学主要驱动因素的转变，最初表面浮力通量占主导，尽管海冰持续减少，但随后转变为风力强迫主导。上层海洋结构和强迫机制的这些变化可能对海洋生态系统产生重大影响，可能导致过去十年中出现异常的秋季浮游植物大量繁殖和海洋酸化加剧的现象。
