Fluctuations in Arctic sea-ice extent: comparing observations and climate models

• Published in: Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences Vol. 376; no. 2129; p. 20170332
• Main Authors: Agarwal, Sahil, Wettlaufer, John S.
• Format: Journal Article
• Language: English
• Published: England The Royal Society Publishing 28.09.2018
• Subjects: Arctic sea ice; Climate models; Decadal timescale; Forecasting; Modeling variability; Modelling studies; Multi-model ensemble; Noise structures; Predictions; Random processes; Satellite observations; Sea Ice; Stochastic Processes; Stochastic systems; Time measurement; Time series; Time series method; White noise; stochastic processes; predictions; sea ice
• ISSN: 1364-503X; 1471-2962; 1471-2962
• DOI: 10.1098/rsta.2017.0332

The fluctuation statistics of the observed sea-ice extent during the satellite era are compared with model output from CMIP5 models using a multifractal time series method. The two robust features of the observations are that on annual to biannual time scales the ice extent exhibits white noise structure, and there is a decadal scale trend associated with the decay of the ice cover. It is shown that (i) there is a large inter-model variability in the time scales extracted from the models, (ii) none of the models exhibits the decadal time scales found in the satellite observations, (iii) five of the 21 models examined exhibit the observed white noise structure, and (iv) the multi-model ensemble mean exhibits neither the observed white noise structure nor the observed decadal trend. It is proposed that the observed fluctuation statistics produced by this method serve as an appropriate test bed for modelling studies. This article is part of the theme issue 'Modelling of sea-ice phenomena'.