Airplanes are scanning the Colorado high country with an array of sensors as scientists search for better ways to measure how much water is locked up in the world's mountain snows.
A NASA-led experiment called SnowEx is testing 10 instruments that might one day be used to monitor snow from satellites. The goal is to find the ideal combination of sensors that can overcome multiple obstacles, including how to analyze snow hidden beneath forest canopies.
NASA says the information is important because one-sixth of the world's population gets most of its water from melted snow.
But estimating how much water the snow contains is difficult because of tree cover, variations in snow layers and liquid water inside snowbanks that can confuse sensors.
SnowEx aims to find a combination of sensors that works best.