Non-stationary drivers of polar sea ice area

Abstract

From 2002 through 2008 the secular rate of de-creasing sea ice area in the northern hemisphere accelerated by a factor of 18, whereas the secular rate of increasing sea ice area in the southern hemisphere accelerated by a factor of 16, relative to the rates from 1978 through 2007. These were derived from the daily sea ice area retrieved from the Scanning Multi-channel Microwave Radiometer – Special Sensor Microwave/Imager and the Advanced Microwave Scan- ning Radiometer for the Earth Observation Sys- tem. The “annual” cycle of northern and southern sea ice areas, the number of days between maxima and minima is 372.4, on average, a frequency modulation, with a recurrence interval of 61.7 years. Significant spectral power occurs at the quasi-4-day through 120-day frequencies. The frequency content and modulation of the daily time series’ are consistent inter-monthly to inter-seasonal frequencies of solar irradiance, atmospheric-oceanic Rossby waves, length-of- day, and polar motion. This suggests conserva-tion of angular momentum of the atmosphere – sea-ice – ocean system. The near 60-year modu- lation and analysis of the detrended daily time series of the Arctic and Antarctic sea ice areas suggest the accelerations shown by the secular trends are relatively short-lived and reversible within an interval of one-quarter (15-years) to one-half (30-years) of the modulation period.