On the time and length scales of the Arctic sea ice thickness anomalies: a study based on fourteen reanalyses
Abstract. The ocean–sea ice reanalyses are the main source of Arctic sea ice thickness information in terms of spatio-temporal coverage, since observations are still sparse in time and space. In this work, we first aim at comparing how the sea ice thickness from an ensemble of fourteen reanalyses compares with different sources of observations, such as moored upward-looking sonars, submarines, airbornes, satellites and ice boreholes. Second, based on the same reanalyses, we intent to characterize the time (persistence) and length scales of sea ice thickness anomalies. We investigate whether data assimilation of sea ice concentration by the reanalyses impacts the realism of sea ice thickness as well as its respective time and length scales. The results suggest that reanalyses with sea ice data assimilation do not necessarily perform better in terms of sea ice thickness compared with the reanalyses which do not assimilate sea ice concentration. However, data assimilation has a clear impact on the time and length scales: reanalyses built with sea ice data assimilation present shorter time and length scales. The mean time and length scales for reanalyses with data ssimilation vary from 2.5–5.0 months and 337.0–732.5 km, respectively, while reanalyses with no data assimilation are characterized by values from 4.9–7.8 months and 846.7–935.7 km, respectively.