Changes in the Ice-Free Period Duration in the Kara Sea Coastal Zone from Satellite Data

Abstract

The rapid Arctic Sea ice shrinkage in the 21st century leads to an increase in the duration of the ice-free period in the Arctic Ocean seas. The ice-free period duration is an important indicator of climate processes for coastal dynamics monitoring in the Russian Arctic zone. The considerable changes in the ice-free period duration significantly affect the functioning of coastal infrastructure, navigation, and coastal ecosystems. Recent satellite microwave sensing data covering the period of more than 40 years of observations make it possible to analyze the state and dynamics of the sea ice cover in the coastal zone of the Russian Arctic. Based on the gradient-threshold method, which was adapted for coastal data, the annual estimates of the ice-free period characteristics for the Kara Sea coastal zone over the period of 1979–2019 are obtained using satellite sea ice concentration data available from different scientific centers (JAXA, OSI SAF, and NSIDC). According to the analyzed satellite data sources, the ice-free period duration in the Kara Sea coastal zone has increased statistically significantly almost everywhere over the past decades. The ice-free period duration has increased due to both earlier melt onset (the average rate of changes is –8 days/decade), and later freeze-up (the average rate of changes is +4 days/decade). The average rates of changes in the total ice-free period duration are +12 days/decade for the period of 1979–2019. The main contribution to the formation of the total ice-free period duration is made by the dynamics of the starting dates of the period, which has high inter-annual variability and a large spatial diversity. The estimates of the ice-free period duration trends allowed for the detection of the most intensely changing areas within the Kara Sea coastal zone: the Yugorsky Peninsula, the western and northern coasts of the Yamal Peninsula. The study specifies the regional features of manifestation of sea ice climate changes within the framework of monitoring of the Russian Arctic coastal dynamics.