Consistent surface fluxes from atmospheric and oceanic reanalyses
Abstract
This talk explores the imbalance in net surface heat, freshwater, and momentum flux at the ocean surface in the MERRA2 and ERA-Int atmospheric reanalyses and the new SODA3 global ocean reanalysis. Initial experiments are presented where the two atmospheric reanalyses are used to drive alternative representations of the ocean reanalysis for the 36 year period 1980-2015. Since the ocean integrates surface fluxes of heat and freshwater any errors in surface flux will accumulate in the ocean and need to be corrected for by the ocean data assimilation. The conservative nature of the ocean budgets and the richness of the ocean observation base during the past 15 years means that we can attribute much of the spatial and temporal structure of the flux errors during this period (determined through examination of the model forecast-data misfits) to biases in the atmospheric reanalyses. The first part of the talk presents the flux errors on seasonal and interannual timescales separately for MERRA2 and ERA-Int and compares them. In the second part of the talk we test our approach by using these flux error estimates to bias-correct the atmospheric reanalysis surface fluxes which are then used to force a second set of ocean reanalysis experiments. We discuss the improvement in model forecast-data misfits due to this bias-correction procedure, which implies that we have improved flux consistency between the two fluid systems. We close the discussion with suggestions regarding the sources of the biases in the atmospheric reanalyses.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNG41B1732C
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3309 Climatology;
- ATMOSPHERIC PROCESSESDE: 3315 Data assimilation;
- ATMOSPHERIC PROCESSESDE: 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSES