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摘要
Oceanic mesoscale eddies interact strongly with the atmosphere, inducing heat flux that acts to dissipate the eddy potential energy. So far it remains unknown how well this oceanic mesoscale eddy-atmosphere (OMEA) interaction is represented in the current generation of general circulation models. Here we evaluate the intensity of OMEA interaction in numerical models widely used by the community. It is found that the intensity of OMEA interaction differs significantly among models in its overall magnitude and spatial distribution. In eddy-rich regions such as Kuroshio Extension and Antarctic Circumpolar Current, the intermodel difference can reach 40%. Surface wind strength and marine atmospheric boundary layer adjustment to mesoscale heat flux anomaly are two important factors accounting for the intermodel difference. Models with stronger surface wind tend to have higher OMEA interaction. Moreover, neglecting the marine atmospheric boundary layer adjustment, ocean-alone model simulations overestimate OMEA interaction especially at middle and high latitudes by 20%-50%. Plain Language Summary Oceanic eddies at mesoscales (100-1,000 km) are the most dominant features in the global ocean, playing a significant role in the transport of mass, heat, and nutrients. Although the generation mechanisms of oceanic mesoscale eddies have been relatively well understood, their energy pathway to dissipation remains unclear. Carrying pronounced sea surface temperature signals, oceanic mesoscale eddies interact strongly with the atmosphere, inducing air-sea heat exchange that acts to damp themselves. Such oceanic mesoscale eddy-atmosphere (OMEA) interaction is found to be an important yet previously overlooked component in the eddy energy dissipation. The accurate representation of OMEA interaction in numerical models is thus essential not only for the correct simulation of eddy energetics but also for the prediction of ocean circulation and climate variability. In this study, we evaluate the intensity of OMEA interaction represented in current generation of general circulation models. It is found that the intensity of OMEA interaction differs significantly among models, implying uncertainties in representing the eddy energy pathway in these models. Two important factors accounting for the intermodel difference are surface wind strength and atmospheric adjustment to the underlying eddies. As wind acts to accelerate the heat exchange at sea surface, models with higher surface wind speed tend to have stronger OMEA interaction. Additionally, the atmospheric adjustment can weaken OMEA interaction through narrowing the air-sea thermal condition difference. Therefore, ocean-alone simulations tend to overestimate OMEA interaction and coupled models are necessary to accurately simulate the energetics of mesoscale eddies and ocean circulations.
- 出版日期2018-11-16
- 单位中国海洋大学
