New GNSS Application Reveals Atmospheric Turbulence's Role in Antarctic Ice Melt

Global Navigation Satellite Systems (GNSS), including GPS, are typically utilized for positioning, timing, and mapping. Now, scientists at MIT Haystack Observatory have reported a new application: using existing GNSS satellites and 13 stations on the Ross Ice Shelf (RIS) in Antarctica to measure atmospheric turbulence. This research suggests that such turbulence may have contributed to extensive surface melting on the RIS in January 2016.

The Ross Ice Shelf: A Crucial Buttress

The RIS is a large, floating ice structure located off the western coast of Antarctica, which buttresses the continental ice sheet. Its stability is important for regulating ice discharge into the ocean from Antarctica, thereby influencing global sea levels. While the RIS normally melts from underneath due to warmer ocean currents, an event in January 2016 involved warm, humid air causing significant surface melting.

GNSS: A New Eye on Atmospheric Conditions

Monitoring atmospheric conditions over the RIS presents challenges due to its remote location. Haystack scientists determined that a network of GNSS stations on the ice can track these conditions. Water vapor in the lower atmosphere causes a delay in GNSS signals, with variations in these delays between stations and over time. These spatial and temporal changes in water vapor allow researchers to monitor weather patterns and infer the strength of atmospheric turbulence over the RIS.

Turbulence Four Times Greater During 2016 Melt Event

During the January 2016 surface melting event, data from the GNSS stations indicated atmospheric turbulence at a level four times greater than typical. This application of GNSS networks offers a method for remotely monitoring atmospheric conditions in distant environments.

"In January 2016, Antarctica experienced a significant widespread summer melting, driven by the warm air intrusion from the Southern Ocean. Our study showed that atmospheric turbulence may have helped mix the air mass and aggravated the surface melting."
— Dhiman Mondal, Haystack Research Scientist

Mondal added that a GNSS network can function as an atmospheric turbulence sensor to monitor the health of ice sheets in areas with limited meteorological measurements.

Broader Implications for Ice Sheet Health

MIT Haystack Observatory has also developed and tested a seismogeodetic ice penetrator for similar monitoring purposes. Plans are underway to extend this GNSS monitoring method to the Greenland Ice Sheet.

Pedro Elosegui, head of the Haystack geodesy department, commented that Antarctic ice shelves like the RIS are generally thinning and retreating. He noted that while ice shelves lose mass through calving icebergs, collapses, and basal melting from ocean interaction, the RIS can also lose mass due to surface melting caused by warm, humid air from the Ross Sea, which contributed to enhanced atmospheric turbulence and potentially intensified the melting.