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

提供资金，利用海洋环流和气候估计联合会开发的基本工具，为气候研究编制允许涡流的北极和次极地北大西洋状态估计。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的限制。目标时期是从1992年至今。通过最小化最小二乘失配函数（伴随或拉格朗日乘数法）实现拟合。利用自动微分法（AD）生成了海洋/海冰耦合伴随模式。类似的努力也已成功完成，编制了南大洋状况估计。除白令海峡以南（66 N）的太平洋区域外，ASTE的区域覆盖26 N以北的大西洋和整个北极。水平分辨率为7至12公里，垂直分辨率为50级。控制空间包括耦合的海洋/海冰状态的初始条件、时变的表面大气状态、时变的开边界条件和空间变化的模式参数。卫星测高的海面高度、每日卫星SST、卫星重力和系泊的平均大地水准面和随时间变化的海底压力、Argo浮标剖面，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（SCICEX）获得的海流计。最初使用的海冰卫星观测将包括：每日冰浓度、被动微波辐射测量、散射测量和合成孔径雷达图像的冰漂移速度。现场冰下数据将包括冰系剖面仪、冰质量平衡浮标、来自潜载上视声纳的冰吃水，以及来自IABP和AON/CADIS档案的各种浮标和系泊数据。对其他数据源的扩展包括测试卫星反演的冰厚或雷达和激光测高组合的干舷数据。他们的方法在整个积分期内提供了计算状态估计的严格动力学一致性，使气候研究相关的精确时变预算计算成为可能，例如在季节和较长时间尺度上评估环流变化及其相关的横向热量和淡水变化。从这个意义上说，该产品与大气环境中所谓的产品有很大不同。重新分析？产品.该产品的另一个新奇是它综合处理北极和副极地环流，并综合所有现有的数据类型。初步的科学重点将是深水形成过程和大西洋赤道翻转之间的联系，高纬度地区的淡水输入及其途径，以及大西洋水，北极盐跃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.