After years of trying to understand the rise in Antarctica sea ice levels compared with the sharp decline in the sea ice of Arctic Ocean, NASA scientists have figured out what exactly is happening.
NASA said the answer lies in the geology of the Southern Ocean and Antarctica.
A multidisciplinary team led by Son Nghiem from the Jet Propulsion Laboratory (JPL) of NASA collected data from satellite radar, ocean depth, temperature at sea surface and land form to study the physical components and processes of the Antarctic sea ice.
With this, they have found that the interplay of the Antarctic's landscape and the waters around it are responsible for the phenomena. The geography influences the movement of the winds, and the depth of the ocean alters the currents. Together they form and change the sea ice cover of Antarctica that helps preserve it.
"Our study provides strong evidence that the behavior of Antarctic sea ice is entirely consistent with the geophysical characteristics found in the southern polar region, which differ sharply from those present in the Arctic," Nghiem said.
The Antarctic sea ice shield is primarily composed of seasonal sea ice, which tops its maximum levels around September before it undergoes about 17 percent reduction come February. For almost 50 years, the changes in the sea ice levels have been steady, but there were noted differences in several areas.
Antarctica's Protective Shield
For quite some time, scientists have been baffled as to why the continent's sea ice continues to rise despite the alarming global warming. In an attempt to understand the region's behavior, the scientists used QuikScat data taken from 1999 to 2009 to identify the movement of the Antarctic sea ice and map it out.
For their study, they singled out the data from 2008, when the seasonal change in Antarctica was at its greatest. They found that as the sea ice grows and forms, the winds push it northward to offshore, which in turn creates a thicker and older sheath of ice that protects the sea ice as it goes around Antarctica. The consistent wind flowing downward shapes the landscape of Antarctica, stacks up the ice toward the ice shield and doubles up its thickness.
As seen in the radar, these older ice covers the younger and thinner ice. When these coverings expand and the ice moves away from the region toward the open water, "ice factories" that promote rapid sea growth are created.
Combination of multiple sea surface temperature satellite data showed that during the season of maximum ice growth, the edge of the ice cover maintains a 30 degree Fahrenheit temperature, which complements the southern Antarctic Circumpolar Current front that divides the warm and cold waters in Antarctica. The scientists also found that the sea surface temperature matches the underwater temperature. This means that the underwater features direct the ocean current that closely corresponds to the surface sea ice patterns.
NASA recently launched its sea level change website to help the public gain a better understanding of the phenomenon.
The study findings and analysis was published in Remote Sensing of Environment.
