How do scientists monitor the Arctic sea ice?
Obtaining reliable measurements of sea ice as it changes was difficult until the satellite era began in the early 1970s. To monitor Arctic sea ice, NSIDC primarily uses the Earth Observing System (EOS) Advanced Microwave Scanning Radiometer (AMSR-E) instrument on the NASA Terra satellite and the Special Sensor Microwave/Imager (SSM/I) instrument on the Defense Meteorological Satellite Program (DMSP) satellite. The satellites pass over the polar region several times each day to gather data; researchers can then form the data into usable information, such as the Sea Ice Index. Scientists can then analyze what they see in the data and report on their findings. Useful satellite data concerning sea ice began in late 1978 with the launch of NASA’s Scanning Multichannel Microwave Radiometer (SMMR) satellite. When scientists compare average sea ice conditions between years, they often use a reference period of 1979–2000. This reference period allows a consistent comparison of changes in extent
