arctic ice acceleration: chirp-z spectral analysis

The longer periods are subject to greater uncertainty due to the relatively short period covered by the satellite data and the fact that longer term variations span several different instruments on different satellite platforms, meaning there is added uncertainly in combining the different data sources into the continuous time series used here.

frequencies less than 2y are progressively attenuated by the filter used to remove the strong annual cycle.

The following link shows a graph that corrects this and uses only the post 1988 data which are more homogeneous. (Earlier data had a 6 day orbital coverage that was processed to bi-daily figures.)