Contributions of advection and melting processes to the decline in sea ice in the Pacific sector of the Arctic Ocean

摘要

The Pacific sector of the Arctic Ocean (PA, hereafter) is a region sensitive to climate change. Given the alarming changes in sea ice cover during recent years, knowledge of sea ice loss with respect to ice advection and melting processes has become critical. With satellite-derived products from the National Snow and Ice Center (NSIDC), a 38-year record (1979–2016) of the loss in sea ice area in summer within the Pacific-Arctic (PA) sector due to the two processes is obtained. The average sea ice outflow from the PA to the Atlantic-Arctic (AA) Ocean during the summer season (June–September) reaches 0.173×10sup6/sup km sup2/sup , which corresponds to approximately 34?% of the mean annual export (October to September). Over the investigated period, a positive trend of 0.004×10sup6/sup km sup2/sup yr sup?1/sup is also observed for the outflow field in summer. The mean estimate of sea ice retreat within the PA associated with summer melting is 1.66×10sup6/sup km sup2/sup , with a positive trend of 0.053×10sup6/sup km sup2/sup yr sup?1/sup . As a result, the increasing trends of ice retreat caused by outflow and melting together contribute to a stronger decrease in sea ice coverage within the PA ( 0.057×10sup6/sup km sup2/sup yr sup?1/sup ) in summer. In percentage terms, the melting process accounts for 90.4?% of the sea ice retreat in the PA in summer, whereas the remaining 9.6?% is explained by the outflow process, on average. Moreover, our analysis suggests that the connections are relatively strong ( R=0.63 ), moderate ( R = - 0.46 ), and weak ( R = - 0.24 ) between retreat of sea ice and the winds associated with the dipole anomaly (DA), North Atlantic Oscillation (NAO), and Arctic Oscillation (AO), respectively. The DA participates by impacting both the advection ( R=0.74 ) and melting ( R=0.55 ) processes, whereas the NAO affects the melting process ( R = - 0.46 ).