国家气候中心全球海洋资料四维同化系统在热带太平洋的结果初步分析

A global 4-dimensional ocean data assimilation system and the studies on its results in the tropic Pacific

介绍了国家气候中心(NCC)“全球海洋资料四维同化系统”(简称NCC-GODAS).该系统包含观测资料预处理系统、插值分析系统和所应用的动力模式.插值分析系统采用四维同化技术方案,在时间上设置一个4周的窗口,将此窗口之内的观测资料以一定的权重插入插值分析系统, 在空间上采用三维变分方案.海洋动力模式为“九五”期间LASG研制的L30T63OGCM 1 0版本.文中考察了该系统从1982年到2003年3月在热带太平洋的部分同化分析结果,并与NCEP的再分析资料和EMC/NCEP的太平洋区域海洋资料同化系统的结果进行了对比分析.结果显示,该系统的同化结果(如SST,SSTA,Nino指数,次表层海温变化等)与NCEP的同期同化结果具有很好的一致性.同时,该系统得出的海洋同化资料气候场与海洋模式气候场相比,有显著的改进.表明该系统具有较好的同化能力,其同化结果可为海-气耦合模式进行季节和跨季节的气候预测业务提供可信的海洋初始场资料,同时还可以为相关研究提供海洋分析场.

We introduce a global 4-dimensional ocean data assimilation system, as one part of operational dynamic model system of National Climate Center, which is routinely serving the marine initial fields for operational dynamic model system. This system mainly contains 4 parts such as pretreating data, variation interpolating and ocean dynamic model and post-treating. Pretreating data includes collecting data, decoding data and data quality control. A 3-dimensional variation method is used in our system on the spatial. Meanwhile, a time-window, about 4-weeks, is opened in order to obtain as more observation information as possible. L30T63 OGCM Version 1.0, which is established and developed by LASG, is selected as the dynamic model of our system.Using the observation data from 1981 to 2003, we have performed a series of numerical experiments on this system. It is illustrated that the results of this system in the region of the middle Pacific, for instances SST, SSTA, Nino index, sub-surface temperature, etc., are coincided with corresponding results of NCEP’s very well. Therefore, this system’s results can be used as the initial fields of relevant ocean dynamic model system as well as a kind of reanalyzed data sets.