Australian sub-regional temperature responses to volcanic forcing: A critical analysis using CMIP5 models

It is now well established that global to local climate is impacted by volcanic forcing associated with major eruptions. Much attention has been given to the way in which climate is affected by such eruptions, particularly for the Northern Hemisphere, and to a considerably lesser extent for the Southern Hemisphere. Research knowledge gaps remain on such forcing impacts at finer sub-regional spatial scales. To this end, we explore temperature responses across eight sub-regions of Australia following three major volcanic eruptions (i.e., Krakatau, 1883; Santa Maria, 1902; Pinatubo, 1991) as simulated by CMIP5 models. We then compare such responses with station and reanalysis datasets. Model outputs indicate strongest temperature responses over more northerly regions than southerly regions of Australia, with weakest responses over Tasmania. Eastern regions of Australia seem to have strongest seasonal cooling during austral autumn, while that for northwestern coastal regions is during austral winter. In contrast, central regions of Australia cool most substantially during austral summer and/or winter, depending on the eruption. Despite such variability, initial temperature responses occur during the warmer austral months (September to February). Uncertainties exist in the reliability of CMIP5 data. For instance, temperature responses from the later Pinatubo eruption seem in stronger agreement with reanalysis data than earlier eruptions (Krakatau and Santa Maria), and while most seasonal temperature responses are stronger than those provided through reanalysis data, they are often weaker in austral spring.