Collaborative Research for WOCE-AIMS: Global Velocity Estimation Project

0137122/0137077 Owens/McWilliamsThis collaborative project will try to estimate the large scale，三维velocity field for the North Atlantic using velocity data from sub-surface floats，current meters，and surface drifters，hydrographic profile，and sea surface height measurements taken before and during the field operations phase of the World Ocean Circulation Experiment（WOCE）.随着GRACE使命的重力测量、JASON使命的高度测量以及实时地转海洋学阵列浮标方案的速度和T、S剖面等新的测量数据的出现，将把它们纳入分析。速度及其预期误差的估计将根据预期测量误差和时空协方差和/或基函数的先验说明，采用广义最小二乘误差最小化方法进行。将使用先验统计的层次结构。它们将根据拉伸盆地基函数的一般谱形和为其他目的运行的数值大气环流模式的模拟分析以及测量的统计分析来确定。模型的协方差和基函数最初将严格执行地转动力学，并在必要时增加额外的非地转过程，如在表面边界层和赤道附近。还将研究直接从模拟计算的约束较小的协方差的使用。估计的后验统计将与先验统计进行比较，以评估估计过程和模型的有效性。将作出一系列全面性不断扩大的估计。最初，这些估计将获得高度采样区域的平均环流，即，大西洋气候和环流实验，然后扩展到第一个盆地，然后全球地图。随着我们对过程的信心增加，也将绘制随时间变化的速度图。最终目标是创建一个活的估算库和软件系统，能够使用用户选择的变量和新数据进行重新估算。该项目是对WOCE的贡献

0137122/0137077 Owens/McWilliamsThis collaborative project will try to estimate the large scale, three-dimensional velocity field for the North Atlantic using velocity data from sub-surface floats, current meters, and surface drifters, hydrographic profiles, and sea surface height measurements taken prior to and during the field operations phase of the World Ocean Circulation Experiment (WOCE). As new measurements, such as the gravimetry from the GRACE mission, altimetry from the JASON mission, and velocities and T and S profiles from the ARGO float program become available, they will be incorporated into the analysis. The estimates of the velocities and their expected errors will be made using generalized least-square error minimization based on a priori specification of expected measurement errors and space-time covariances and/or basis functions. A hierarchy of a priori statistics will be used. They will be determined from general spectral shapes for stretched basin basis functions and analyses of simulations from numerical general circulation models run for other purposes, as well as statistical analyses from the measurements. The model covariances and basis functions initially will exactly enforce geostrophic dynamics, with additional ageostrophic processes added where necessary, such as in the surface boundary layer and near the Equator. The use of slightly less constrained covariances calculated directly from the simulations will also be examined. The a posteriori statistics of the estimates will be compared with the a priori ones to evaluate the estimation procedure and the validity of the models. A sequence of estimations with expanding comprehensiveness will be made. Initially these estimates will be obtained for the mean circulation in highly sampled regions, i.e., the Atlantic Climate and Circulation Experiment and then expanded to first basin then global maps. As we gain confidence in the procedure, maps for temporally varying velocities will also be made. The ultimate goal is to create a living estimation library and software system, capable of user-chosen variants and re-estimation with new data. This project is a contribution to WOCE