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New Way to Look at Precipitation: What’s the Footprint on the Ground?

By LIDA TUNESI

CUNY researchers have come up with a new way to think about and predict extreme precipitation events. Their work will be helpful to everyone from reservoir managers and local governments to climate change researchers.

Professors Naresh Devineni (City College of New York) and James Booth (CCNY, The Graduate Center), master’s degree student Carolien Mossel, Ph.D. graduate Nasser Najibi and undergraduate alum Ariel Mazor authored the paper, published in JGR Atmospheres.

Many studies on extreme precipitation look at its possible causes and the trends of recent decades. Instead, the new study looks at the space that precipitation covers on the ground—its footprint, so to speak. This approach “has invaluable benefits to determine the probability of a specific region undergoing a high risk of inundation and sudden deluge,” Devineni said.

The researchers examined what they dubbed “simultaneous heavy precipitation events,” or SHPEs. To qualify, an event has to be statistically extreme and cover a very large space. The precipitation caused by a hurricane, for example, would likely count as a SHPE. They then devised a way to quantify an event’s footprint, by finding its center and approximating the area as an ellipse (a stretched-out circle).

Using this method, the researchers dug through recorded observations of precipitation from 1900 to 2014 to form a historical database of SHPEs in the U.S., and studied the events’ features, seasonal patterns, and related atmospheric processes. Finally, they put together their findings to create a seasonal spatial risk model to predict when and where a SHPE is likely to happen in the future.

The new model will be useful for floodplain management, for predicting damages to infrastructure like transportation networks and food supply chains, and for other scientists in the hydroclimatology field.