During the 2020 La Nina, many areas of Australia received near average to severely below-average rainfall, particularly during November. CLEX researchers found that several compounding factors contributed to the drier-than anticipated spring conditions.
To better understand the implications of the latest climate science for Tasmania, this brief combines information from the IPCC AR6 WG1 report, with regional assessments that contributed to the UTAS Blueprint for a climate-positive Tasmania, and expertise from the Australian Research Council Centre of Excellence for Climate Extremes (CLEX). The regional information is based on Tasmania-specific downscaled modelling undertaken by Climate Futures for Tasmania.
It has long been suggested in the literature, and discussed casually by meteorologists, that rainfall in Melbourne often occurs as lines of precipitation. However, this had yet to be quantified. CLEX researchers analysed 15 years of radar data from the Australian Radar Archive, using an objective method to identify and track these ‘linear systems’ based on radar reflectivity, size, and shape characteristics.
Hydrological impact studies analyse the effects of climate change on hydrological variables, such as changes in soil moisture, streamflow or hydrological extremes. This project aims to investigate the realised added value effect of model bias correction and downscaling methods on hydrological projections for Australia.
In Melbourne, 50% of rainfall and 75% of extreme daily rainfall occurs on days with at least one linearly organized convective system. However, thunderstorms are often localized events, and much of the rainfall in a region falls over a short period of time. Furthermore, not all thunderstorms necessarily occur in lines, and organized storms that lead to extreme sub-daily rainfall may be different from those that lead to extreme daily rainfall. This projects aims to identify and categorize organizational structures linked with the most intense rainfalls in the region.
Ozone depletion over Antarctica from the late 1970s to 2000 has been linked to changes in the surface climate over the Southern Hemisphere in summer, among them a more positive Southern Annular Mode (SAM). Over Australian latitudes, a more positive SAM is associated with increased rainfall over eastern Australia in the summer season. Given stratospheric ozone over Antarctica is projected to recover to 1980 levels by ~2050, the impact of ozone recovery on its own would be to reduce this upward trend in summertime rainfall over eastern Australia.
Due to the lack of appropriate historical datasets, quantification of shifts in global extreme precipitation intensity has not been possible so far. This project will use a recently developed long-term global dataset of daily precipitation alongside a dataset of global temperature changes to calculate the CC scaling for broad climatic regions across the globe.
As part of CLEX’s engagement with the agricultural sector, Chief Investigators Ailie Gallant and Andrea Taschetto presented an overview of some of the Centre’s relevant research interests to the monthly meeting of the Forewarned is Forearmed Community of Practice (FWFACoP) group in June 2021.
Sopia Lestari (CLEX/University of Melbourne). Understanding variability of rainfall extremes in Jakarta and surrounding regions. Location: Online (Teams). Please email sig-seminars-admin@bom.gov.au for details of Microsoft Teams link to join.
The accumulation of rainfall over a given area depends on a range of things, including duration, intensity, and propagation speed. It is the characteristics of convection that ultimately determine these rainfall properties. The idea for this project is to use a simple method to characterise the properties of the most intense convective / rainfall bearing systems from radar data.