ABSTRACT

The Brazilian Oceanographic Modeling and Observation Network (REMO, acronym for ‘Rede de Modelagem e Observação Oceanográfica’ in Portuguese) has developed the REMO Ocean Data Assimilation System (RODAS). It is based on an Ensemble Optimal Interpolation scheme applied into the Hybrid Coordinate Ocean Model (HYCOM). This study aims to investigate the extended-range predictability of the HYCOM + RODAS System over the western South Atlantic by using its analyses as initial condition for 48 hindcasts, each covering 30 days. The outputs were compared to persistence (no change from the initial condition) and to a model free run. The hindcasts had the lowest root mean square difference (RMSD) and highest correlation of sea surface temperature (SST) and sea level anomaly (SLA) at all lead times. By the 30th day, persistence RMSD reached 1.09°C and 0.08 m for SST and SLA, respectively, while the hindcast RMSD reached 0.46°C and 0.05 m. The free run RMSD was almost constant with an average of 0.88°C and 0.13 m. In the subsurface, hindcast RMSD increase was even lower. The results suggest that HYCOM + RODAS predictive skill extends for more than a month and the thermohaline state of the ocean was consistently improved with respect to the free model run.

摘要

巴西海洋学建模和观测网络（REMO，葡萄牙语为“ Rede de Modelagem eObservaçãoOceanográfica”的缩写）已经开发了REMO海洋数据同化系统（RODAS）。它基于应用于混合坐标海洋模型（HYCOM）的集成最优插值方案。这项研究的目的是通过使用HYCOM + RODAS系统的分析作为48个后预报的初始条件，每个时长30天，来研究南大西洋西部的HYCOM + RODAS系统的扩展范围可预测性。将输出与持久性（与初始条件不变）和模型自由运行进行比较。后预报在所有提前期均具有最低的均方根差（RMSD）和最高的海面温度（SST）与海平面异常（SLA）相关性。到第30天，持久性RMSD达到1.09°C和0。SST和SLA分别为08 m，而后播RMSD分别为0.46°C和0.05 m。自由运行RMSD几乎恒定，平均为0.88°C和0.13 m。在地下，后播RMSD的增加甚至更低。结果表明，HYCOM + RODAS的预测能力已延长了一个多月，并且相对于免费模型运行，海洋的热盐状态得到了持续改善。