The Arctic Subpolar Gyre sTate Estimate: Description and Assessment of a Data‐Constrained, Dynamically Consistent Ocean‐Sea Ice Estimate for 2002–2017
The Arctic Subpolar Gyre sTate Estimate: Description and Assessment of a Data‐Constrained, Dynamically Consistent Ocean‐Sea Ice Estimate for 2002–2017
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DOI：
10.1029/2020ms002398
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发表时间：
2020-11
影响因子：
6.8
通讯作者：
A. Nguyen;H. Pillar;V. Ocaña;A. Bigdeli;Timothy Smith;P. Heimbach
中科院分区：
文献类型：
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作者：
A. Nguyen;H. Pillar;V. Ocaña;A. Bigdeli;Timothy Smith;P. Heimbach
介绍了北极次极地涡旋状态估计(ASE_R1)的首次发布，这是一个数据约束的海-海冰模式-数据合成。ASTE_R1的标称分辨率为1/3°，时间跨度为2002-2017年。通过基于伴随的非线性最小二乘优化，实现了该模型对大量(O(109))卫星和现场观测数据的拟合。与无约束模拟相比，该解决方案的改进体现在失配减少了77%，卫星海面高度减少了50%，弗拉姆海峡系泊减少了58%，冰系留剖面仪减少了65%，海冰范围减少了83%。精确的动力学和运动学一致性是ASTE_R1的一个关键优势，它将状态估计与现有的海洋再分析区分开来。通过严格遵守守恒定律，ASTE_R1内的所有源和汇都可以被考虑在内，从而能够在网格尺度上对封闭的预算进行有意义的分析，例如水平和垂直辐合对热量和盐分趋势的贡献。因此，ASTE_R1是迄今为止进行的最大努力，以产生21世纪专门的北冰洋冰估计。在重要的北冰洋地中海门户上，流量、热量和淡水的传输与公布的基于观测的估计一致。淡水和热量的年际变化和低频趋势在巴伦支海、北极西部盐跃层和北大西洋东部次极地表现得很好。ASTE_R1仍然存在系统性偏差，包括北极大西洋水层的温暖偏差，以及来自河流和格陵兰排放的淡水输入不足。
A description and assessment of the first release of the Arctic Subpolar gyre sTate Estimate (ASTE_R1), a data‐constrained ocean‐sea ice model‐data synthesis, is presented. ASTE_R1 has a nominal resolution of 1/3° and spans the period 2002–2017. The fit of the model to an extensive (O(109)) set of satellite and in situ observations was achieved through adjoint‐based nonlinear least squares optimization. The improvement of the solution compared to an unconstrained simulation is reflected in misfit reductions of 77% for Argo, 50% for satellite sea surface height, 58% for the Fram Strait mooring, 65% for Ice Tethered Profilers, and 83% for sea ice extent. Exact dynamical and kinematic consistency is a key advantage of ASTE_R1, distinguishing the state estimate from existing ocean reanalyses. Through strict adherence to conservation laws, all sources and sinks within ASTE_R1 can be accounted for, permitting meaningful analysis of closed budgets at the grid‐scale, such as contributions of horizontal and vertical convergence to the tendencies of heat and salt. ASTE_R1 thus serves as the biggest effort undertaken to date of producing a specialized Arctic ocean‐ice estimate over the 21st century. Transports of volume, heat, and freshwater are consistent with published observation‐based estimates across important Arctic Mediterranean gateways. Interannual variability and low frequency trends of freshwater and heat content are well represented in the Barents Sea, western Arctic halocline, and east subpolar North Atlantic. Systematic biases remain in ASTE_R1, including a warm bias in the Atlantic Water layer in the Arctic and deficient freshwater inputs from rivers and Greenland discharge.