New Generation of Global Ocean Data Assimilation System at NCEP

Stylianos Flampouris1, Guillaume Vernires2, Travis Cole Sluka3, Jessica Meixner4, Jong Kim1, Jian Kuang5 and Shastri Paturi6, (1)IMSG/NOAA-NCEP-EMC, College Park, MD, United States, (2)JCSDA/UCAR/NOAA, College Park, United States, (3)Joint Center for Satellite Data Assimilation, Boulder, United States, (4)NOAA/NWS/NCEP/EMC, College Park, United States, (5)IMSG at NOAA/NWS/NCEP/EMC, College Park, MD, United States, (6)Axiom/NOAA-NCEP-EMC, College Park, United States
The National Centers for Environmental Prediction (NCEP) of NOAA are responsible for the operational Global Ocean Data Assimilation System (GODAS), the products of which demonstrate less than the desired accuracy. As part of the ongoing efforts to improve the operational products, and in the framework of the Unified Forecasting System, the next generation of GODAS is under development, sharing only the same name with its predecessor.

The model used for the new system is the coupled model of NCEP based on the Global Forecasting System with FV3 core (GFS-FV3), the Modular Ocean Model (MOM) version 6 and the Los Alamos sea ice model (CICE5). The data assimilation system is hybrid (3DVar/EnKF), and it is based mainly on the Sea-Ice Ocean and Coupled Assimilation (SOCA) utilizing the Joint Effort for Data assimilation Integration (JEDI). The perturbations for the EnKF component are calculated by using the Universal Multi-Domain Local Ensemble Transform Kalman Filter (LETKF) algorithm. The system ingests in situ temperature and salinity and satellite SST and altimetry observations. The horizontal resolution of the GODAS is ¼ degree, with 75 vertical hybrid coordinate levels and runs in a daily cycle.

The new generation of GODAS has fundamental advantages over the operational system and produced significant improvements in the analysis of temperature, salinity, sea surface height. During this presentation, the preliminary results from the retrospective run of the system will be presented and discussed in comparison with passive observations and the current operational GODAS.