The Role of Katabatic Outflow in Maintaining the Upper Level Antarctic Winter Vortex

Brief description

The data set associated with this project is a long simulation from a global climate model, with data saved every 6 hours. Also part of the simulated atmospheric data in the project is the results of sensitivity studies which were designed to assess the impact of changes in Antarctic katabatic flow. Among these are simulated data with enhanced surface friction, and with the removal of Antarctic topography.

From the abstract of the referenced paper:

The results of some published studies have been interpreted to suggest that transports associated with the intense katabatic flow field over the Antarctic continent are important factors influencing the development of the upper level winter vortex over the continent. Some of these studies have been rather simplistic and their results may have been taken out of context.

We have undertaken some experiments with a model which includes the effects of many feedbacks and synoptic forcing. In this model we have artificially weakened the katabatic flow and assessed the impact on the upper-level vortex. We have effected this weakening by:

1) 'removing' the Antarctic topography, and
2) increasing the surface momentum drag coefficient over Antarctica.

We find a weakened upper-level vortex circulation in the no-topography experiment but a strengthened vortex in the increased drag experiment. The difference in response can be traced to the nature of the reaction of the tropospheric thermal field. Our results indicate that there is no simple, unambiguous relationship between the strength of the katabatic flow and the depth of the upper-level vortex.