Radar Characteristics of Storms in the Sydney Area

Abstract

The characteristics of radar echoes for 12 thunderstorm days in the vicinity of Sydney, Australia, in the summer of 1995/96 have been examined using an objective methodology for storm identification and tracking. The spatial distribution of identified storms shows a maximum in frequency and intensity along the east side of the mountains that lie inland from the coast. Characteristics such as storm volume, area, and height are shown to have a lognormal frequency distribution. Reflectivity also has a skewed frequency distribution with a prevalence of lower reflectivity storms. Both the maximum reflectivity and storm height are shown to be correlated with the logarithm of storm volume. Although small storms predominate, the bulk of precipitation flux comes from the relatively few large-scale storms. It is also shown that storms generally move or propagate in a direction slightly to the left of the mass-weighted mean wind for the surface-to-300-hPa layer at a speed slightly less than the mean speed. Furthermore the deviation of the storm to the left of the mean layer wind increases and the standard deviation decreases as the storm size increases.