资源环境科技发展态势分析平台

Previous study indicated that changes in the Arctic sea ice concentration (ASIC) during boreal autumn in the Laptev-eastern Siberian-Beaufort Seas have a marked influence on the interannual variation of Arctic oscillation (AO) during following spring. This study reveals a pronounced enhancement of the linkage between autumn ASIC changes and following spring AO since the mid-1990s. The correlation coefficient between the autumn ASIC and spring AO index reaches 0.72 during 1998-2014. During this period, autumn ASIC decrease results in pronounced tropospheric warming over the high latitudes and a reduction of meridional temperature gradient. This leads to decrease in circumpolar westerly winds and increase in the upward propagation of quasi-stationary wave, which weakens stratospheric polar vortex. Then, spring AO becomes weaker than normal via the interaction between stationary wave and mean flow and the accompanying downward propagation of anomalous easterly winds. Before the mid-1990s, however, decrease in the autumn ASIC is not followed by an obvious change in the overlying air temperature. Accordingly, circumpolar westerly winds and polar vortex experience weak changes. Thus, the linkage between the autumn ASIC and following spring AO is weak. It is suggested that interdecadal change in the impact of autumn ASIC on the spring AO is attributed to a change in the interannual variability of autumn ASIC. Specifically, interannual variability of autumn ASIC is much larger after the mid-1990s, which contributes to stronger stratospheric response and ASIC-spring AO connection.