What's the Rainfall Count? It Depends

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Posted on February 21, 2019

Alice Jackson

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Synoptic meteorologist and associate professor Dr. John Lanicci came to the right place two years ago when he joined the University of South Alabama faculty, because his research into extreme weather events is a good fit with the Mobile region, where it rains more than any other metropolitan area in the United States.

“I focus on the study of what people call extreme weather events. Those are weather events that don’t occur very often, but when they do, it’s on a large or record-setting scale,” Lanicci explained. These events may include phenomena such as heavy rainfall, droughts, snowstorms or heat waves.

Lanicci received an internal funding grant of $5,000 from the University’s Office of Research and Economic Development for “Numerical Modeling of an Extreme Rainfall Event in a Future Climate.” Lanicci and three meteorology students will completely analyze 15years of data he collected during a unique study of rainfall on the Space Coast of Florida for the National Aeronautics and Space Administration. NASA commissioned his initial study as part of an initiative to investigate the vulnerabilities of its facilities and infrastructure to global climate change, and mitigate present coastal erosion in the vicinity of Kennedy Space Center’s launch complexes believed to be caused by climate change and sea-level rise.

“I used a high-density network of 36 rain gauges around the area of the Kennedy Space Center, which was basically 12-by-18 miles, or 216 square miles,” Lanicci said. “The area included a lot of critical infrastructure, which the government wants to protect from the effects of climate change. We expected the average and extreme (rare-event) rainfall in that area to be somewhat homogenous, or uniform, because we had gauges literally a mile or less away from each other, but the data shows it was anything but that. What surprised us was the wide variability of collected and estimated extreme rainfall over this area.”

The amount of annual rainfall varied as much as 16 inches over an area approximately one-eighth the size of Mobile County. The variability in estimated extreme rainfall is also dramatic.

The collection area included portions of the Banana River, a 31-milelagoon system that flows into the 121-mile-long Indian River, which in turn forms part of the Atlantic Intracoastal Waterway. It was around the rivers that Lanicci found the greatest variations of rainfall.

“The Indian and Banana rivers were large enough to produce their own local river breezes. Plus, the area was impacted by the sea breeze from the Atlantic Ocean to the east. The interactions between the individual river and sea breezes and the associated summertime thunderstorms led to the variation of rainfall within the area,” Lanicci said. “In layman’s terms, the bodies of water and the land are so complex geographically that it creates local weather effects.”

This means urban planners and environmental engineers – the people who now use tables projecting 30 years or more into the future when they design water flow and storm drainage systems, as well as determine sizes of pipes, terrain slopes and retention ponds – are likely missing “some very important local effects.”

“That is where the climate change part came into it. One of the assumptions is that the climate during that period is stationary, but the problem is if the climate is getting warmer and the sea level is rising, you want to take that into consideration,” Lanicci said.

Lanicci has served since 2012 as chair of the Committee on Environmental Security of the American Meteorological Society, a position that looks at how extreme weather events and climatic anomalies can disrupt national and international security.

In the future, he’s looking forward to similar studies along the northern Gulf Coast.

“With all the changing weather in this region, including hurricanes, there’s definitely plenty to research,” Lanicci said.

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