Modelling spatial and temporal rainfall and their relationship to climatic indicators in South Australia

Abstract

A spatial model for daily rainfall based on an ordinal logistic regression for the number of wet sites and an ordinary regression for average depth of rainfall at wet sites is presented. The model is fitted to daily rainfall records from a cluster of seven meteorological stations, at the meso-gamma meteorological scale, in South Australia. Data covering a 55-year period from 1958 to 2012 is analysed. The model is used to identify associations between rainfall and four climatic indicators, namely the Southern Oscillation Index (SOI), the Southern Annular Mode (SAM), the Indian Ocean Dipole (IOD) and the Pacific Decadal Oscillation (PDO), and also to monitor changes in rainfall patterns. The results show that there is strong evidence of seasonal variations, in both depth and spatial extent of rainfall, and of persistence of the rainfall pattern from day to day. There is no evidence of trends, but there is evidence of a spatial association between rainfall and SOI, SAM and IOD. There is also evidence of an association between rainfall depth and PDO.