EO4AgroClimate: Evaluating the structure and evolution of Australian East Coast Lows using a new Southern Hemisphere cyclone atlas

Lead Research Organisation: University of Reading
Department Name: Meteorology

Abstract

Australian agricultural production is greatly influenced by the weather and climate. The largest cropping region is located in the south-east of Australia where mild temperatures and abundant rainfall create an environment suitable for large crop yields. Several times a year intense low pressure systems, known as East Coast Lows, can bring heavy rain to southern Queensland, New South Wales and eastern Victoria. If this heavy rain is persistent or several lows pass over the same region in rapid succession, they can cause flooding and extensive crop damage. Therefore it is important to understand how these lows evolve in order to improve predictions of their motion and intensification. East Coast Lows can be difficult to forecast due to their small size and rapid intensification over the southern Pacific. Satellite derived data products are particularly important in these situations as they provide observations used as input to weather forecast models in regions where surface based observations are sparse. In this project we will investigate the evolution of Southern Hemisphere lows with a particular focus on the East Coast Lows that bring heavy precipitation to south-east Australia. By creating three-dimensional composites of their structure we aim to deepen our understanding of the mechanisms leading to their rapid development. We will create a southern hemisphere extratropical cyclones atlas that will be a tool for other researchers to study these high impact hazardous events.

Publications

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Dacre H (2023) Precipitation Efficiencies in a Climatology of Southern Ocean Extratropical Cyclones in Journal of Geophysical Research: Atmospheres

 
Description Precipitation efficiency is a measure of how much water in the atmosphere falls as rain compared to how much is available to fall. In this project, we estimate how efficient precipitation is for 400 cyclones in the Southern Ocean. We find that when the cyclones are strongest, about 60% of the available water vapour turns into rain every 6 hr near the warm front of the cyclone where air is rising rapidly. Normally, within a day or two of a cyclone forming, all of the available water vapour in the cyclone gets turned into rain. However, the rain can persist for longer because cyclones pick up more moisture as they move, which gets turned into more rain. This can make the rain from a cyclone last on average for 60 hr, even after the initial moisture is all gone.
Exploitation Route It would be interesting to investigate the precipitation efficiencies in different types of East Coast Lows.
Sectors Environment