Collaborative Research: An eddy-permitting Arctic & Sub-Polar State Estimate for climate research

利用海洋环流和气候估算（ECCO）联盟开发的基本工具，为气候研究提供了一个允许涡旋的北极和亚极地北大西洋状态估算（ASTE）。耦合海洋/海冰环流模式（MITgcm）将受到尽可能多的海洋和海冰观测资料的限制。目标时期是从1992年至今。拟合将通过最小化最小二乘不拟合函数（伴随或拉格朗日乘数法）来实现。采用自动分异（AD）方法建立了海洋/海冰耦合模式。类似的努力也已成功完成，编制了《南大洋状况评估》。东南纬向风的范围包括26北纬以北的大西洋和整个北极，白令海峡以南（66北纬）的太平洋部分除外。水平分辨率为7至12公里，垂直高度为50个。控制空间包括海洋/海冰耦合状态的初始条件、时变地表大气状态、时变开放边界条件和空间变化的模型参数。最初用于海洋的观测主干网包括：来自卫星测高的海面高度、每日卫星海温、来自卫星重力和系泊的平均大地水准面和随时间变化的底压、Argo浮子剖面、来自WOCE和PHC的水文数据、可用的系泊阵列，如Line-W和RAPID/MOCHA，以及通过AON/CADIS、PANGEAE （ASOF）和NSIDC （sciex）提供的海流计。最初使用的海冰卫星观测将包括：日冰浓度、被动微波辐射测量的冰漂移速度、散射测量和SAR图像。冰下的原位数据将包括冰系剖面仪、冰质量平衡浮标、潜载向上看声纳的冰流，以及来自IABP和AON/CADIS档案的各种浮标和系泊数据。对其他数据来源的扩展包括测试卫星检索的冰厚或从雷达和激光联合测高得到的干舷数据。他们的方法在整个整合期间提供了计算状态估计的严格动态一致性，从而实现了与气候研究相关的精确时变预算计算，例如在季节和更长时间尺度上评估环流变化及其相关的侧向热量和淡水变化。从这个意义上说，该产品与大气环境中所谓的“再分析”有很大不同。产品。该产品的另一个新颖之处在于它对北极和亚极地环流的综合处理，以及所有可用数据类型的综合。最初的科学重点将放在深水形成过程与大西洋经向翻转之间的联系，高纬度地区的淡水输入及其途径，以及大西洋水、北极盐斜层形成和海冰之间的相互作用。

Funds are provided to produce an eddy-permitting Arctic and sub-polar NorthAtlantic state estimate (ASTE) for climate research, using basic tools developed within the Estimating the Circulation and Climate of the Ocean (ECCO) consortium. The coupled ocean/sea-ice general circulation model (MITgcm) will be constrained by as many ocean and sea-ice observations as available and practical. The target period is from 1992 to present. The fit will be achieved through minimization of a least-squares misfit function (adjoint or Lagrange Multiplier method). The coupled ocean/sea-ice adjoint model has been generated by means of automatic differentiation (AD). A similar effort has been successfully accomplished with the production of the Southern Ocean State Estimate (SOSE). The domain of the ASTE covers the Atlantic northward of 26 N and the entire Arctic, with the exception of the Pacific sector southward of Bering Strait (66 N). The horizontal resolution is 7 to 12 km with 50 vertical levels. The control space comprises the initial conditions of the coupled ocean/sea-ice state, the time-varying surface atmospheric state, time-varying open boundary conditions, and spatially varying model parameters.The observational backbone used initially for the ocean consists of: sea surface height from satellite altimetry, daily satellite SST, mean geoid and time-varying bottom pressure from satellite gravity and moorings, Argo float profiles, hydrographic data from WOCE and PHC, available mooring arrays such as Line-W and RAPID/MOCHA, and current meters available via AON/CADIS, PANGEAE (ASOF), and NSIDC (SCICEX). Sea-ice satellite observations used initially will comprise: daily ice concentration, ice drift velocities from passive microwave radiometry, scatterometry, and SAR imagery. In-situ under-ice data will include ice-tethered profilers, ice mass balance buoys, ice draft from submarine-borne upward looking sonar, as well as various buoy and mooring data from the IABP and AON/CADIS archives. Extension to other data sources includes tests of satellite retrievals of ice thickness or freeboard data from combined radar and laser altimetry.Their approach offers strict dynamical consistency of the computed state estimate over the entire integration period, enabling exact time-varying budget calculations relevant for climate studies, such as the assessment of circulation shifts and their associated lateral heat and freshwater changes on seasonal and longer time scales. In this sense, the product differs significantly from what in the atmospheric context are called ?re-analysis? products. Another novelty of the product is its combined treatment of the Arctic and the subpolar gyre, and the synthesis of all available data types. Initial science foci will be on the connection between deep water formation processes and the Atlantic meridional overturning, the freshwater input at high latitudes and its pathways, and the interaction between Atlantic Water, Arctic halocline formation, and sea-ice.