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Abstract:
There are plenty of oceanic eddies in the ocean which may have significant influences on tropical and extratropical cyclones. However, the impacts of eddies on polar low (PL) have been rarely investigated. In this study, the influence of oceanic mesoscale eddies on the PL simulation is investigated based on a case study and 4 winter-year simulations. The case study shows that the PL was weakened (intensified) when it goes through a cold (warm) eddy. Increasing heat fluxes induced by warm eddy strengthened the secondary circulation of the PL through released condensational diabatic heating, which enhanced PL intensity. The cold eddy would induce the opposite process to decrease PL intensity. Four winter-year simulations with the domain covering the Nordic Sea indicate that oceanic eddies enhance the transfer of water vapour to the atmosphere. Substantially, the oceanic eddies enhance the PL intensity and size statistically, by increasing the condensational latent heating release. Meanwhile, the high PL track density areas are shifted a bit north when the influence of oceanic eddies is resolved. These finds improve our understanding of the interactions between PL and oceanic states, and imply that high-resolution lower boundary data is necessary to be considered for improving the ability of PL forecasting.
