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Towards a dynamically balanced eddy-resolving ocean reanalysis: BRAN3
journal contribution
posted on 2023-05-19, 08:42 authored by Oke, PR, Sakov, P, Cahill, ML, Dunn, JR, Fiedler, R, Griffin, DA, Mansbridge, JV, Ridgway, KR, Andreas SchillerAndreas SchillerThe generation and evolution of eddies in the ocean are largely due to instabilities that are unpredictable, even on short time-scales. As a result, eddy-resolving ocean reanalyses typically use data assimilation to regularly adjust the model state. In this study, we present results from a second-generation eddy-resolving ocean reanalysis that is shown to match both assimilated and with-held observations more closely than its predecessor; but involves much smaller adjustments to the model state at each assimilation. We compare version 2 and 3 of the Bluelink ReANalysis (BRAN) in the Australian region. Overall, the misfits between the model fields in BRAN3 and observations are 5-28% smaller than the misfits for BRAN2. Specifically, we show that for BRAN3 (BRAN2) the sea-level, upper ocean temperature, upper-ocean salinity, and near-surface velocity match observations to within 7.7. cm (9.7. cm), 0.68. °C (0.95. °C), 0.16. psu (0.18. psu), and 20.2. cm/s (21.3. cm/s) respectively. We also show that the increments applied to BRAN3 - the artificial adjustments applied at each assimilation step - are typically 20-50% smaller than the equivalent adjustments in BRAN2. This leads us to conclude that the performance of BRAN3 is more dynamically consistent than BRAN2, rendering it more suitable for a range of applications, including analysis of ocean variability, extreme events, and process studies.
History
Publication title
Ocean ModellingVolume
67Pagination
52-70ISSN
1463-5003Department/School
Institute for Marine and Antarctic StudiesPublisher
Elsevier Sci LtdPlace of publication
The Boulevard, Langford Lane, Kidlington, Oxford, England, Oxon, Ox5 1GbRights statement
Copyright 2013 Elsevier Ltd.Repository Status
- Restricted