A Modelling Study of the Baroclinicity and Surface Fronts Near the Ice-edge
Abstract
Advection of cold and stable Arctic air over a warm ocean generates a shallow lower-level front with sharp temperature contrasts. A baroclinic response of this contrast results in a low-level jet. This may often be associated with a strong background flow, thus localized extreme winds may occur. The lower-level baroclinicity may couple with upper-level potential vorticity anomalies and lead to cyclogenesis. In this study, the formation of surface fronts and baroclinic waves is investigated in an idealized baroclinic channel by using a state-of-the-art high-resolution numerical model. The investigation is carried out with various background conditions such as horizontal temperature gradient, upper-level jet conditions etc. The initial results show the formation of a shallow boundary layer due to surface fluxes over the ocean, and consequently a shallow front is formed at the ice-edge. The strength of the jet response depends first of all on the surface inversion over the ice, but also to some degree on the sea surface temperature. A typical value for the response is 10m/s. As long as the boundary layer depth becomes deeper than the inversion over the sea ice, the full potential of the lower-level jet response is obtained. One of the background conditions tested was an upper-level jet. The interaction between the jets turned out to be limited, but when the upper-level jet was perturbed, a cyclonic development was initiated, coupling with the lower-level disturbance.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.A51E0149B
- Keywords:
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- 1704 Atmospheric sciences