Non-stationary Drivers of Polar Sea Ice Area

From 2002 through 2008 the secular rate of decreasing 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 Scanning Radiometer for the Earth Observation System. 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 conservation of angular momentum of the atmosphere – sea-ice – ocean system. The near 60-year modulation 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.