Anomalous Variability in Antarctic Sea Ice Extents During the 1960s With the Use of Nimbus Data

The Nimbus I, II, and III satellites provide a new opportunity for climate studies in the 1960s. The rescue of the visible and infrared imager data resulted in the utilization of the early Nimbus data to determine sea ice extent. A qualitative analysis of the early NASA Nimbus missions has revealed Antarctic sea ice extents that are significant larger and smaller than the historic 1979-2012 passive microwave record. The September 1964 ice mean area is 19.7 × 10⁶ km²± 0.3 × 10⁶ km². This is more the 250,000 km² greater than the 19.44 × 10⁶ km² seen in the new 2012 historic maximum. However, in August 1966 the maximum sea ice extent fell to 15.9 × 10⁶ km² ± 0.3 × 10⁶ km². This is more than 1.5 × 10⁶ km² below the passive microwave record of 17.5 × 10 ⁶ km² set in September of 1986. This variation between 1964 and 1966 represents a change of maximum sea ice of over 3 × 10⁶ km² in just two years. These inter-annual variations while large, are small when compared to the Antarctic seasonal cycle.