An object-based climatology of precipitation systems in Sydney, Australia

The climate is warming and this is changing some aspects of storms, but we have relatively little knowledge of storm characteristics beyond intensity, which limits our understanding of storms overall. In this study, we apply a cell-tracking algorithm to 20 years of radar data at a mid-latitude coastal-site (Sydney, Australia), to establish a regional precipitation system climatology. The results show that extreme storms in terms of translation-speed, size and rainfall intensity usually occur in the warm season, and are slower and more intense over land between similar to 10 am and similar to 8 pm (AEST), peaking in the afternoon. Precipitation systems are more frequent in the cold season and often initiate over the ocean and move northward, leading to precipitation mostly over the ocean. Using clustering algorithms, we have found five precipitation system types with distinct properties, occurring throughout the year but peaking in different seasons. While overall rainfall statistics don't show any link to climate modes, links do appear for some system types using a multivariate approach. This climatology for a variety of precipitation system characteristics will allow future study of any changes in these characteristics due to climate change.

Automated summary

The study examines a coastal site in Sydney, Australia, using 20 years of radar data to establish a regional precipitation system climatology. The findings reveal that extreme storms with high translation-speed, size, and rainfall intensity usually occur in the warm season, specifically between 10 am and 8 pm. Precipitation systems are more frequent in the cold season and typically initiate over the ocean and move northward. Clustering algorithms identify five distinct precipitation system types that peak in different seasons. Although there is no overall link between rainfall statistics and climate modes, some system types show connections using a multivariate approach.