Mean southern hemisphere extratropical cyclone behavior in the 40-year NCEP-NCAR reanalysis

Abstract

This paper presents a new climatology of Southern Hemisphere (SH) extratropical cyclones. This has been compiled by applying a state-of-the-art cyclone tracking scheme to the 6-hourIy National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) global reanalyses spanning the period 1958-97. The results show there to be, on average, between 35 and 38 cyclonic systems per analysis (depending on season), with the greatest density [exceeding 6 x 10' cyclones (deg lat)2] found south of 60°S in all seasons and in the Indian and west Pacific Oceans in autumn and winter. For the most part, there is a net creation of cyclones (i.e., cyclogenesis exceeds cyclolysi..