USA, 15 May 2007: A team of NASA scientists has found an evidence showing extensive areas of snow melted in west Antarctica in January 2005 in response to warm temperatures. This was detected with NASA’s QuikScat satellite. Using data from QuikScat, they measured snowfall accumulation and melt in Antarctica and Greenland from July 1999 through July 2005.
The observed melting occurred in multiple distinct regions, including far inland, at high latitudes and at high elevations, where melt had been considered unlikely. Evidence of melting was found up to 900 kilometers (560 miles) inland from the open ocean, farther than 85 degrees south (about 500 kilometers, or 310 miles, from the South Pole) and higher than 2,000 meters (6,600 feet) above sea level. Maximum air temperatures at the time of the melting were unusually high, reaching more than five degrees Celsius (41 degrees Fahrenheit) in one of the affected areas. They remained above melting for approximately a week.
Son Nghiem of NASA’s Jet Propulsion Laboratory said, “We need to know what’s coming in and going out of the ice sheets.” He added “QuikScat data, combined with data from NASA’s IceSat and Gravity Recovery and Climate Experiment satellites, along with aircraft and ground measurements, all contribute to more accurate estimates of how the polar ice sheets are changing.”
QuikSCAT’s scatterometer instrument sends radar pulses to the ice sheet surface, measuring the echoed pulses that bounce back. When snow melts and then refreezes, it changes to ice, just as ice cream crystallizes when it is left out too long and is then refrozen. QuikScat can differentiate this icy fingerprint in the snow cover and can map on a continental scale the extent of strong snowmelt and the subsequently formed ice layer. Available ground station measurements validate the satellite results.
The study, “Snow Accumulation and Snowmelt Monitoring in Greenland and Antarctica,” appears in the recently published book “Dynamic Planet.”
