A recent study has linked drought occurrence in Australia to minute variations in the wettest weather.
The study, which was directed by Dr. Tess Parker of the Australian Research Council Centre of Excellence for Climate Extremes at Monash University, demonstrates that severe drought was exacerbated by a few fewer days of heavy precipitation each year.
The investigation is being conducted at a time when today’s State of the Climate report indicates a long-term drop in rainfall in southern Australia.
The authors showed that the absence of just 3-5 days of heavy rain across 120 years of Australian rainfall data was typically responsible for significantly more than half of the rainfall drop during previous droughts.
“The majority of rainfall comes from these heavy rainfall days (above 20 mm/day), which is typically only 1-2 weeks’ worth of annual rainfall, sometimes less,” Dr Parker said.
“But it’s the slight reduction of this heavy rain, equivalent to around five or fewer days per year on average, that is responsible for most of the rainfall decline during past drought, right across Australia.”
The study also demonstrates that the return of these days of heavy rain is the reason why droughts end.
They frequently result in wetter than usual weather, nevertheless.
“Droughts typically break in spectacular fashion because those heavy rain days return to excess, rather than just returning to normal. This shows that drought-breaking rains can also be down to relatively few, but heavy, rainfall events,” Dr Parker said.
“In wetter climates, like on the east coast, it’s days with rainfall above 50 mm that make the biggest difference.”
According to Dr. Parker, the relevance of the results resides in the connections that may be drawn to weather systems that bring rain, which produce substantial rainfall that can make or break droughts.
“Our study has isolated the importance of days of heavy rainfall for drought development and recovery. Now this is known, we can begin to investigate the types of weather systems related to these heavy rainfall days, which will reveal a lot about important meteorological processes that send us into and out of drought,” Dr Parker said.
The BOM claims that of Australia’s many climate-related problems, drought is one of the most costly and feared.
A significant portion of southern Australia endured a severe Millennium drought from 1997 to 2010.
Droughts not only cause agricultural failure but also stock loss, bushfires, dust storms, and soil degradation.
“Effective monitoring and prediction is required to manage and mitigate the socioeconomic effects of drought. This requires knowledge of how droughts begin, develop and recover, and the underlying processes related to these stages of drought,” Dr Parker said.
Source: Monash University
