The mPing project lets amateur weather-watchers with Android or iOS smartphones collect ground-truth for professional meteorologists. Scientists at the National Oceanic and Atmospheric Administration and the University of Oklahoma created the app because they needed a way to fill the gaps in weather radar coverage. Amateurs submitted over 250,000 observations during the winter of 2012-2013 alone.
Weather radar systems like Noaa’s Nexrad doppler radar save lives every day. Water droplets and ice crystals reflect the radar’s microwave signal which lets meteorologists track storms and issue weather alerts. But radars have inherent weaknesses that make things difficult for the meteorologists. The microwave beam does not reach the ground which leaves meteorologists blind to what’s happening close to the ground. That gap starts at the radar tower and gets taller as the beam travels away from the tower. A lot can happen in the hundreds of meters between the radar beam and the ground, especially in the winter. Rain can turn into snow. Snow can turn into rain. What looks like precipitation in the radar image may never reach the ground at all. Even with the latest algorithms processing the data, Noaa’s meteorologists can’t be certain what’s happening far from the radar towers. That uncertainty can lead meteorologists to issue warnings for things that aren’t happening - or worse, fail to issue warnings for things that are happening. To keep that from happening they depend on volunteer observer programs like Cocorahs and SkyWarn produce reports of actual weather conditions - the ground truth.
Researchers at Noaa and the University of Oklahoma want to improve the algorithms that analyze Nexrad data so meteorologists get better information. They released the mPing smartphone app to let a broad range of amateur weather watchers gather ground-truth data on local rain and freezing precipitation. When weather moves in, the mPing amateurs identify the type of precipitation. The app submits an anonymous report with the precipitation type, time, and GPS data. The Ping Data Viewer on the project’s website lets you explore the reports and create animations that track a storm’s precipitation over time.
The project team published a paper about mPing in the Bulletin of the American Meteorological Society (doi:10/1175/BAMS-D-13-00014.1) that explains the limits of doppler systems and the current algorithms. They also showed that the amateurs report weather conditions as accurately as professional meteorologists.