Arctic Ocean circulation from radar altimetry
Katharine Giles, Seymour Laxon, Andy Ridout,
At CPOM we use satellite radar altimetry data to measure how the Arctic Ocean circulation is changing. Altimeters measure the sea surface height and from this we can calculate how the surface circulation of the ocean is changing. In the past it has been difficult to do this in the Arctic because its ocean is covered by a layer of ice. But new processing techniques, developed at University College London (UCL), mean that we now have continuous measurements over the Arctic (up to 81.5°N) from the European Space Agency (ESA) missions ERS-1, ERS-2 and Envisat. CryoSat2, which was launch in April 2010, now provides coverage of the Arctic Ocean up to 88°N for the first time.
The following figure shows a map of the Arctic Ocean Dynamic Topography (DT) for January and February 2011 from CryoSat-2 (the scale is in metres). DT is the sea surface height with respect to the Earth’s gravity field. It is made from data from CryoSat-2, which has been combined with data from the Envisat satellite in areas where there is no ice cover.
Our most recent discovery, using data from the ERS-2 and Envisat satellites, shows an increase in freshwater over the western Arctic of 8000 ± 2000 km3 between 1995 and 2010. You can read more about this finding in our news item here.