Zonal Teleconnections and Longitude-Time Lag Correlations of the 500 mb Geopotential along 50° S

Abstract

Unfiltered, band- and low-pass filtered geopotential height values of the 500 mb level along 50°S are analyzed to evaluate teleconnections and zonal wave-propagation properties in the Southern Hemisphere (SH) midlatitudes. Correlation matrices of low-pass filtered data illustrate the dominant patterns of hemispheric and regional anomalies: the transpolar teleconnection, the South American anomaly and a stationary wavenumber 3 pattern (with contributions from wavenumbers 2 and 4). Longitude-time lag correlations of the low-pass filtered data document an eastward energy dispersion along a quasi-stationary zonal wave train; it emerges from the area of South America, has a wavelength of 90 to 100° longitude, and a group velocity of ?10° per day. The bandpass filtered correlation matrices for this latitude circle reveal the sectors of the major storm tracks. The related longitude-time lag correlations show a wavelength of 70° to 80° longitude, an eastward propagation of ?10° per day and a group velocity of ?50° per day.