Abstract
Information on the timing of Arctic snow and ice melt onset, sea ice opening, retreat, advance, and closing, can be beneficial to a variety of stakeholders. Sea ice modelers can use information on the evolution of the ice cover through the rest of the summer to improve their seasonal sea ice forecasts. The length of the open water season (as derived from retreat/advance dates) is important for human activities and for wildlife. Long-term averages and variability of these dates as climate indicators are beneficial to business strategic planning and climate monitoring. In this study, basic characteristics of temporal means and variability of Arctic sea ice climate indicators derived from a satellite-based climate data record from March 1979 to February 2017 melt and freeze seasons are described. Our results show that, over the Arctic region, anomalies of snow and ice melt onset, ice opening and retreat dates are getting earlier in the year at a rate of more than 5 days per decade, while that of ice advance and closing dates are getting later at a rate of more than 5 days per decade. These significant trends resulted in significant upward trends for anomalies of inner and outer ice-free periods at a rate of nearly 12 days per decade. Small but significant downward trends of seasonal ice loss and gain period anomalies were also observed at a rate of −1.48 and −0.53 days per decade, respectively. Our analyses also demonstrated that the means of these indicators and their trends are sensitive to valid data masks and regional averaging methods.
Highlights
Since late 1978, passive microwave sensors have been providing a history of sea ice concentration from satellite data suitable for tracking climate change and variability in the polar regions
We describe temporal mean and variability of Arctic climate indicators derived from a long-term satellite-based sea ice concentration climate data record
By utilizing our integrated data set with all of these parameters, this study provides a new way to holistically look at the changing seasonality of the Arctic sea ice cover
Summary
Since late 1978, passive microwave sensors have been providing a history of sea ice concentration from satellite data suitable for tracking climate change and variability in the polar regions. Sea ice extent (the area within the 15% concentration contour) and area (the area-integrated concentration) have long been considered as key climate indicators and have been included in numerous national and international climate assessment reports (e.g., [1,2]). These two parameters provide only limited information about the character of the sea ice; in addition, they have limited skill as indicators of future sea ice conditions, both seasonally and inter-annually [3]. Ipnethriiosdpsa,pienrn, er andwdaoetuedste,esrsceriacibeie-cfetrheoeeptpeenemirnipogod,rsrael(tamrseeadate,nfiasdnavenaddnicvnea,Traiaanbbdlielict1lyoasonifndtghdedeafsotcelrlsio,bwseediansbgoenilnoadlwiic.c)aetolorss:ssannodwgaanind ice melt periods, onset inner and outer ice-free Tpaebriloed1s.
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