Tas Uni helps align ice observations
Seeking ground truth for the CryoSat-2 mission
How’s this for a summer activity: dragging a GPS hundreds of kilometers across Antarctic ice to grab a GPS measurement?
That’s been the programme for researchers from the University of Tasmania, along with collaborators from Germany’s Alfred Wegener Institute, in a project designed to validate measurements from the European Space Agency’s CryoSat-2.
The research groups’ work has been to collect a validation dataset in which CryoSat-2 observations are taken almost simultaneously with researchers on the ground and in aircraft.
CryoSat-2, part of the space agency’s Living Planet programme, is designed to take accurate measurements of the thickness of floating sea ice, to detect annual variations as they happen, and to try and build a sufficiently-accurate sea ice survey to detect small changes in ice thickness.
The validation mission, completed earlier this month, is designed to get a dataset that provides a “ground truth” measurement that can be compared to the satellite’s measurements.
According to UTAS geodesist Dr Christopher Watson, the mission sought out regions “where we know the ice is changing relatively quickly. Accurate satellite data is vital in observing and then understanding contributions of Antarctica to sea level rise.”
Locations in the survey included Law Dome and the Totten Glacier. The first is relatively stable, but has very steep surface slops; while the glacier is already known to be changing rapidly.
The measurement programme involved coordinating the ground measurements with four surveys by the Polar-6 aircraft operated by the Alfred Wegener Institute, along with the satellite measurements. The ground team had the job of taking both topographical measurements and observations of snow and ice properties.
The Polar-6 aircraft carries a radar designed to mimic the radar carried on the CyroSat-2.
Veit Helm from the Alfred Wegener Institute said the ground observations are important to deriving accurate results from the satellite modelling. "“Depending on factors such as snow particle size, the extent to which it has compacted and how it is layered, the radar signal can penetrate deeper or less deep and so is reflected differently.
“If we ignore these factors in the data, it may result in misinterpretations and less accurate maps of the changing Antarctic surface.” ®
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