Windshield Wipers Measure Rainfall; GPS-Equipped ‘RainCars’ Could Help Predict Flooding

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Researchers in Germany are pioneering new ways to measure rainfall using gps-equipped “RainCars.” The idea is to use the cars' windshield wipers to measure the intensity of precipitation in real time, over vast distances, unlike conventional rain gauges, which are static and can only measure rainfall in one spot.

Engineers from the University of Hanover tested ways to use sensors on windshield wipers that would track rainfall based on the car’s location. Windshield wipers on several modern car models use a system of infrared laser beams to measure the intensity of rainfall against a car’s windshield and automatically adjust the speed of the wipers accordingly. Researchers hope to use this technology in a new way and to better predict flooding.

"If moving cars could be used to measure rainfall, the network density could be improved dramatically," Uwe Haberlandt, who led the project, said in a statement. "The value of using moving cars to measure rainfall is not about a higher accuracy of rainfall measurements but about a much higher number of measurement points.”

Their study, published in the journal Hydrology and Earth System Sciences, details the experiments the team conducted to see whether or not windshield wipers are a good estimate of rainfall intensity. Armed with a rain simulator, researchers tested windshield wiper speeds both with a volunteer manually adjusting their speed and with automatic adjustment sensors.

"The optical sensors measure the rain on the windshield in a more direct and continuous manner so, currently, they would be the better choice for rain sensors in cars,” Haberlandt concluded.

Researchers performed their experiments under ideal conditions. But Haberlandt and his team recognized that in the real world, measuring rainfall with windshield wipers could prove tricky. For one, the car will be in constant motion, meaning they’ll have to figure out how a car’s movement affects the sensor readings and adjust the numbers to offset those differences. 

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