UTSA engineer wants to improve the accuracy of the daily forecast

(May 14, 2018) -- Firat Testik, professor of civil and environmental engineering at The University of Texas at San Antonio (UTSA), has received a three-year, $430,581 grant from the National Science Foundation to support his work about the microphysics of rainfall. Testik will use the funding to better understand the fundamental dynamics of raindrops, which could lead to better rainfall estimations and climate modeling in the future.

The average person is used to seeing a weather forecast on television based on radar data, which is used to measure the amount of rainfall in any single area. The technology works by sending directional pulses of microwave radiation that bounce off the raindrops and send signals back indicating the amount of rainfall.

“There are uncertainties and errors associated with weather radar,” Testik said. “This system relies on an assumption of the size distribution of raindrops, which is currently impossible to accurately predict. Our goal is to be able to better understand the size distribution and velocity of falling raindrops under different environmental conditions.”

Additionally, radar assumes all drops fall from the sky at terminal speeds. In a previous research project, Testik created an observation tool that allowed him to see that raindrops fall at different velocities and can have vastly different shapes and sizes than those assumed in radar estimations, which can affect attempts to predict the intensity of rainfall.

“This is very fundamental research, so it can have a vast array of applications,” he said. “In addition to improving weather radar predictions, this knowledge can be utilized for telecommunications applications to prevent their signals from being disrupted. It could even be applied to understand soil erosion over time.”

The central focus of Testik’s work going forward will be to better understand the collisions between raindrops as they fall from the sky. He’s previously noted that especially large drops break apart before they reach the ground, but often times will swallow many other drops on their way down.

“The idea is to have a comprehensive understanding of the way the wind and turbulence of a storm affects the motion of these drops,” Testik said. “Our current technology is only giving us its best guess when it estimates rainfall. We can do better, and with this new wider knowledge we will do better.”

Testik joined UTSA in 2015. He is the director of the UTSA Flow Physics Laboratory, which focus on the study of a wide range of natural and man-made flow problems in coastal, oceanic, atmospheric and overland environments.

— Joanna Carver

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