Researchers at MIT Haystack Observatory have turned the world's navigation satellites into an instrument for studying Antarctic melting. In a study published in Geophysical Research Letters, the team revisited a January 2016 surface melting event on the Ross Ice Shelf using signals from existing GNSS constellations, including GPS, received at 13 stations installed across the shelf.
The method exploits a nuisance that geodesists usually correct away: water vapour in the lower atmosphere delays satellite signals, and those delays vary from station to station and moment to moment. By tracking the fluctuations, the researchers inferred the strength of atmospheric turbulence above the ice. During the melt event, turbulence climbed to roughly four times its usual level, consistent with vigorous mixing that could have drawn warm, humid air from the Southern Ocean down over the shelf and aggravated the surface melt.
The approach matters because the Ross Ice Shelf buttresses the West Antarctic ice sheet, whose fate bears directly on global sea levels, yet weather observations across it are sparse. A GNSS network that doubles as a turbulence sensor offers continuous, remote monitoring of locations too dangerous or costly to instrument conventionally, and the Haystack team now plans to extend the technique to Greenland.