On the Detection of Weather Systems over the Antarctic Interior in the FROST Analyses

Abstract

The first Special Observing Period (SOP-1) of the Antarctic First Regional Observing Study of the Troposphere (FROST) was completed in July 1994 and provided a unique opportunity to assemble a comprehensive dataset for the Antarctic region. Data obtained from this intensive collection effort have been undergoing analysis at several centers around the world, including Hobart in Australia. The synoptic analysis program for SOP-1 has been completed in Hobart and, additionally, a reanalysis of a ?special week? (22?28 July) has been undertaken, enabling 500-hPa contour fields to be constructed for the region south of 50°S. Results of these analyses for continental Antarctica are presented and comparisons made with operational analyses from numerical models. Satellite imagery from the Defense Meteorological Satellite Program (DMSP) was employed in the special week reanalysis and has provided evidence of several vortices that moved southward over East Antarctica during the latter part of July 1994 and appeared to decay over the high plateau. Observations from the network of automatic weather stations (AWSs) over East Antarctica were combined with satellite imagery to infer the movement inland of these cyclones. It is demonstrated that broadscale and synoptic-scale influences contributed to the migration of cyclones over East Antarctica during SOP-1 and, in particular, an association is established between the incidence of atmospheric blocking activity in the Tasman Sea and the inland penetration of lows. The early identification of circulation features in satellite cloud imagery when a favorable broadscale environment has been established and the interpretation of anomaly fields using Antarctic AWSs offer possibilities for the better prediction of the tracks of these small but significant systems.