Photos taken of snowfall and posted online could help fill holes in satellite weather data caused by cloud cover, says Indiana University Ph.D. student Haipeng Zhang.
Zhang and colleagues examined 150 million photos on the Web site Flickr that had been geo-tagged in the United States. They used software to analyze the image's tags and visual features to estimate the presence of snow, then applied a statistical test to determine a measure of confidence in that estimate. The number of accurately identified photos in each location indicated whether or not it had snowed in that area. The Flickr photos estimated snowfall with 95 percent accuracy, when compared with observations from ground-based weather stations in New York City, Boston, Chicago, and Philadelphia.
Although the Flickr photos were much less accurate when tested against nationwide satellite data, Zhang believes any photos taken could be useful for strengthening sparse satellite data. The Flickr photos were less accurate for non-urban snowfall because smartphone and social media use is lower in rural areas.
From New Scientist
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