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Meso-scale dynamics along the sea-ice edge

The sea-ice edge in the Arctic very often features a meso-scale low-level jet stream in the atmosphere. These rather small scale phenomena are still purely respresented in wearther foreasting models.

Vertical cross-section through a sea-ice edge jet south of Svalbard
Vertical cross-section through a sea-ice edge jet south of Svalbard
Photo:
Stefan Keiderling

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Marine activities at high latitudes are often encountering difficult conditions.  Two severe factors are strong winds and resulting rough seas. The goal is to make better forecasts so that operations in the Arctic seas can receive more precise warnings and thus prepare better for potentially dangerous situations. This can be achieved by more research on the special features of the lower Arctic troposphere. Therefore this work will focus on low-level jet streams at the sea ice edge. Since this topic has not been much in the focus of previous studies there are rather few observations

 

The cross-sections along the ice edge illustrate the low level jet. The aim is to detect sensitivities to certain atmospheric parameters. It is hypothesized that strong boundary layer fronts are causing these strong winds parallel to the ice edge. These boundary layer fronts are explained by the theory of semi-geostrophic frontogenesis. Differential heating leads to pressure gradients across the ice edge which drive an ageostrophic vertical circulation. As a response the geostrophic wind along the ice edge increases. A task will be to identify the sensitivity of the jet location to parameters like geostrophic wind direction, stability, heat fluxes.

Contact at GFI: Thomas Spengler