(Sen) - Scientists have produced the first map of the ebb and flow of Arctic sea ice throughout an entire winter season.
The map, which is the most accurate and extensive yet made, was created using data from the European Space Agency's CryoSat-2 satellite and covers the Arctic region up to 88 degrees north (the Pole is at 90 degrees).
Launched two years ago, CryoSat is designed to monitor changes in the thickness and extent of ice in both the Arctic and Antarctic.
The CyroSat maps clearly show the changes in ice coverage and volume over the winter. Credit: ESA
The map, created by the Centre for Polar Observation and Modeling (CPOM) at University College London was presented at the Royal Society in London on April 24. It has demonstrated how CryoSat’s radar system can used to estimate the volume of sea ice at the Poles. The data will improve our understanding of long-term changes in Polar ice.
It is the first map of its kind to created using a radar altimeter, which fires a pulse of microwaves at the ice. CryoSat can calculate its exact height by measuring the time it takes for the pulses to bounce back.
The pulses bounce off the top of the ice and water in the cracks (called leads) separating the floes. By measuring the difference between the two surfaces, scientists can calculate the volume of the ice.
The CryoSat team has also published a digital elevation model of Greenland, which is losing tens of billions of tonnes of ice every year. Credit: ESA
The Cryosat mission was originally due to launch back in 2005 but was lost in a catastrophic launch failure.
The original CryoSat was designed to test the theory that Arctic ice was indeed declining, but observed record lows in Arctic summer sea ice already proved that.
CryoSat-2 is the first craft to be able to measure the volume of ice loss. Data from the mission will also be used to determine what the consequences of that ice loss will be and how they will be felt across the globe.
One consequence of a loss of surface ice is that circulation patterns at the oceans’ surface might be affected, which could, in turn, have a wider effect on the deep-sea ‘conveyor belt’ that carries cold water from the poles to the equator and back again.
From an altitude of 700km, CryoSat-2 precisely monitors (to within a few centimetres) changes in the thickness of the polar ice sheets both on land and at sea, significantly adding to the information gleaned from previous missions.
The craft is just one piece in a jigsaw of ESA missions called the Earth Explorer programme. CryoSat-2 is the third (of the eventual six) core missions to be launched.
The first, launched in March 2009, was a gravity mapper called GOCE. The second, known as SMOS, was launched in November 2009 and is tasked with measuring soil moisture levels and ocean salinity.
Still to come are missions designed to measure the Earth’s magnetic field, its cloud cover and global winds.