Assessing the impact of assimilating atmospheric data on the ocean state estimation and climate forecast in an ensemble coupled data assimilation system
Abstract
The ocean initial condition is usually considered to the most important factor for climate forecast. It is unclear if assimilation of atmospheric data is helpful or not to get a good ocean initial condition. In this paper, we use an Ensemble Coupled Data Assimilation system (ECDA) to explore the impacts of assimilating atmosphere data on ocean state estimation and climate forecast. Through several idealized twin experiments by ECDA system, we demonstrate that the achieved ocean initial conditions are improved significantly by further adding the atmospheric observation as constrains. Further analysis reveals that the use of atmosphere data leads to more accurate estimation of the ocean surface flux terms including the heat flux, the fresh water flux and the wind stress, consequently, better estimation of ocean SST, SSS, and the surface ocean currents. It is also demonstrated that the atmosphere data's impact is not just limited to the surface layers, rather the impact can penetrate all the way to the deep ocean. By decomposing the velocity into barotropic and baroclinic part, we found that the deep penetration of the atmosphere data's impact may be through the correction of the barotropic part of the ocean currents. This impact also differs by oceans.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS41F2083W
- Keywords:
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- 3315 Data assimilation;
- ATMOSPHERIC PROCESSESDE: 1622 Earth system modeling;
- GLOBAL CHANGEDE: 1627 Coupled models of the climate system;
- GLOBAL CHANGEDE: 4263 Ocean predictability and prediction;
- OCEANOGRAPHY: GENERAL