Southern Hemisphere storm tracks, blocking, and low-frequency anomalies in a primitive equation model

Abstract

In both seasons, the fastest-growing cyclogenesis models have largest amplitudes in the eastern part of the hemisphere just downstream of the polar jet stream maxima. In July, there is a tendency to form elongated eddies in the region downstream of Australia where growth on both polar and subtropical jet streams occurs. These results are in general agreement with the observational studies of Southern Hemisphere storm tracks. For both January and July, larger-scale slower-propagating dipole or multipole modes are found that are consistent with blocking in some or all of the observed locations in the Australian/New Zealand region, east of the Falklands, and to the southeast of South Africa. The faster-growing low-frequency anomaly modes have their primary centers located to the south of 60°S and have features in common with either or both of high-latitude and wavenumber 3 observed Southern Hemisphere teleconnection patterns. -from Authors