NASA / NOAA Climate

World - Breaking waves and moisture transport drive extreme precipitation events

Around the world each year, extreme precipitation events cause catastrophic flooding that results in tragic loss of life and costly damage to infrastructure and property. However, a variety of different weather systems can cause these extreme events, so a detailed understanding of the atmospheric processes that lead to their formation is crucial.

Now, for the first time, a global analysis reveals that two intertwined atmospheric processes drive the formation of many large-scale extreme precipitation events around the world, particularly in dry subtropical regions where they can inflict catastrophic flooding, as occurred in March 2015 in the Atacama Desert.

Previous research on extreme precipitation events has mostly focused on wet regions, where cyclones are typically responsible for these events, whereas dry subtropical regions have been less studied. However, it is precisely these dry subtropical regions, including deserts, "where these mysterious events are least expected, but can cause devastating impacts," says Andries-Jan de Vries, an atmospheric scientist at ETH Zürich and the Max Planck Institute for Chemistry in Mainz, Germany, who authored the new study.

The results, published in the European Geosciences Union (EGU) journal Weather and Climate Dynamics, improve our understanding of atmospheric processes and weather systems that lead to extreme precipitation events. This, in turn, could help improve forecasts, perhaps leading to the development of early warning systems that could save lives.

The results could also improve our understanding of how these extreme events will respond to climate change. The intensity and frequency of these heavy rainfall events have been increasing in recent decades, and the trend is projected to continue under global warming.

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Read also A global climatological perspective on the importance of Rossby wave breaking and intense moisture transport for extreme precipitation events, Andries Jan de Vries, Sept. 5, 2020.

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