Exploring the effect of Arctic perennial sea ice on modulation of local air temperature

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Sea ice cover plays an important role in modulating local temperature through heat and moisture fluxes. The influence of thin ice, lead and polynya has been well investigated, however, the effect of perennial ice (also called multiyear ice, MYI) has not. This study is motivated by it and investigated a hypothesis that changes in MYI concentration in winter triggers changes in short-term local 2-m air temperature. The hypothesis was tested using time series analysis of the two parameters and correlation between them. Data from the winters of 2004–2009 were used for the examination at three spatial scales. The hypothesis is found to be potentially accepted when MYI exists in a consolidated ice regime with negligible thin ice or open water in the surroundings, and the air temperature is low enough. Conditions for the acceptance of the hypothesis were quantitatively identified. The qualifications entail that the ice cell must experience daily change of MYI concentration meanwhile satisfy the criteria of total ice concentration (TIC), young ice concentration (YIC) and air temperature (Tair) in the surrounding area, which are TIC >88.3%, YIC <9.5% and Tair<–19.0 °C. Inverse relationships between changes in MYI concentration and the corresponding changes in air temperature were developed retroactively using data that satisfied the acceptance conditions. The relationships varied with years, depending on ice conditions such as ice type distributions and snow cover. This study offers a first attempt to assess the effect of MYI on the same-day local surface air temperature using satellite observations, and provides evidence of this effect under quantitatively quanlifying conditions.