Major advances in ocean forecasting at the Bureau of Meteorology
Dr Gary Brassington1, Pavel Sakov1, Prasanth Divakaran1, Xinmei Huang1, Saima Aijaz1, Charles Sanders1, Stewart Allen1, Russell Fiedler2, Matthew Chamberlain2, Peter Oke2, Andy Hogg3, Andrew Kiss3, Petra Heil4, Christopher Bladwell1, Xiaobing Zhou1, Jessica Sweeney-van Kinderen1, Aihong Zhong1, Mikhail Entel1, Ahmad Khan1
1Bureau Of Meteorology, Melbourne, Australia, 2CSIRO, Hobart, Australia, 3Australian National University, Canberra, Australia, 4Australian Antarctic Division, Hobart, Australia
The Bureau of Meteorology completed the first stage of a major upgrade to its Ocean Model, Analysis and Prediction System (OceanMAPS) in June 2022. This interim version (OceanMAPSv4.0i) focused on the implementation of an ensemble Kalman Filter (EnKF) method for the ocean data assimilation. Specifically, a hybrid-EnKF method was introduced based on 48 dynamic members and 144 stationary members. The second stage of the major upgrade will include the adoption of the global coupled ocean and sea-ice model developed under the COSIMA partnership permitting the first sea-ice forecasts.
The OceanMAPSv4.0i shows many significant improvements over the previous system including analyses with improved dynamical balance and forecasts with robust reductions in mean absolute difference against all reference observations including Jason-series altimetry, Argo profiles, in situ SST and currents. Encouragingly, the forecasts of near surface ocean currents have the lowest mean absolute difference compared with all major international global ocean forecast systems.
We will describe the design of the system and the new products that extend the range of downstream applications that the Australian community can exploit. These include a 48-member ensemble hindcast, 3 synchronous forecasts, 7 asynchronous forecasts and a 16-member average restart deterministic forecast. Several other unregistered products from the analysis system provide information on the ensemble spread and the impact of observations.
There are several specific areas where the performance can be further improved or extended. These include maximising the real-time data assimilated, further collaborations in ocean and coupled modelling, ocean-sea-ice data assimilation, ensemble and extended range forecasting. We will describe a number of specific developments for a further upgrade to the interim system; progress on stage two of the major upgrade; a planned 10-year reanalysis of the EnKF system; as well as developments for a NEMO-based system for coupled weather forecasting.
Biography:
Dr Gary Brassington is one of Australia’s leading researchers in ocean forecasting. He is the Bureau of Meteorology’s Senior Principal Research Scientist for Ocean Modelling and leads award winning teams that research, develop and deploy operational ocean forecast systems including the Ocean Model, Analysis and Prediction System (OceanMAPS). OceanMAPS is developed and sustained through a government partnership of the Bureau of Meteorology, CSIRO and Australian Defence Force. Dr Brassington is the national representative for the OceanPredict science team since 2006 and the inaugural chair of the Expert Team on Operational Ocean Forecast Systems.
