气候变化领域集成服务门户

To track sea ice motion, four ice-tethered buoys were deployed at 84.6 degrees N and 144.3 degrees W, 87.3 degrees N and 172.3 degrees W, 81.1 degrees N and 157.4 degrees W, and 82.8 degrees N and 166.5 degrees W in summers of 2008, 2010, 2014, and 2016, respectively. In addition, the remote sensed ice motion product provided by National Snow and Ice Data Center was used to reconstruct backward and forward ice drifting trajectories from the buoy deployment sites during 1979-2016. Sea ice in the central Arctic Ocean in late summer is trending to have travelled from lower latitudes, and to be advected to the region more involved in the Transpolar Drift Stream (TDS) during 1979-2016. The strengthened TDS has played a crucial role in Arctic sea ice loss from a dynamic perspective. The trajectory of ice is found to be significantly related to atmosphere circulation indices. The Central Arctic Index (CAI), defined as the difference in sea level pressure between 84 degrees N, 90 degrees W and 84 degrees N, 90 degrees E, can explain 34-40% of the meridional displacement along the backward trajectories, and it can explain 27-40% of the zonal displacement along the forward trajectories. The winter Beaufort High (BH) anomaly can explain 18-27% of the zonal displacement. Under high positive CAI values or high negative winter BH anomalies, floes from the central Arctic tended to be advected out of the Arctic Ocean through Fram Strait or other marginal gateways. Conversely, under high negative CAI values or high positive winter BH anomalies, ice tended to become trapped within a region close to the North Pole or it drifted into the Beaufort Gyre region. The long-term trend and spatial change in Arctic surface air temperature were more remarkable during the freezing season than the melt season because most energy from the lower troposphere is used to melt sea ice and warm the upper ocean during summer.