| Summary: | Progress Code: completed Statement: See the referenced papers for further information. Using the ECMWF analyses for the three FROST periods, a data set has been extracted to show the anomalous mean sea level pressure over these periods. In addition a comprehensive analysis of all cyclones in the sub Antarctic region during the special observing periods is part of the set. From the abstracts of some of the referenced papers: The data collected during the three special observing periods (SOPs) of the Antarctic First Regional Observing Study of the Troposphere project provide an excellent base upon which to study the behaviour of cyclonic systems in winter, spring, and summer in the Southern Hemisphere. This paper provides a report on the behaviour of these cyclonic systems during the three SOPs as revealed in the twice-daily ECMWF operational analyses. The study has been undertaken with an objective cyclone tracking algorithm applied to the digital analyses. The results revealed cyclone behaviour generally in accord with long-term climatologies developed with this scheme. In the SOPs the authors observed many systems to be generated in the western part of the ocean basins and then to move east and, to a lesser extent, south. In the three periods they found a concentration of tracks just to the north of the Antarctic continent, being particularly noticeable in the Indian Ocean. At the same time, they found significant differences in cyclone behaviour between the climatology and the SOPs in specific regions. The monthly mean sea level pressure (MSLP) anomalies during the SOPs were quite large (and exceeded 10 hPa in places), particularly in the Pacific and in the region to the south of Australia. It appears that the anomalous cyclone structure during the SOPs could be related to the anomalies of the MSLP. The authors suggest that the three SOPs cannot be regarded as typical of their time of year, but it could be argued that no specific period could be so regarded. The results obtained with these high quality ...
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