资源环境科技发展态势分析平台

Using the ERA-20th century reanalysis data for the period 1900-2009 and NCEP/NCAR reanalysis data for the period 1948-2016, this work inspects the interdecadal variations between Arctic Oscillation (AO) and the surface air temperature (SAT) in East Asia, then investigates possible mechanisms, and finally considers a recent switch of the AO-SAT relationship. It is revealed that the AO-SAT relationship is statistically significant during 1928-1948 and 1975-1995. It means that positive AO is associated with significant weakening of the sea level pressure (SLP) gradient over East Asia, East Asian trough, and East Asian jet stream. However, the AO-SAT relationship is statistically insignificant and there is little significance in the AO-related circulation during 1905-1925 and 1950-1970. Further examination revealed that the unstable AO-SAT relationship might be attributable to the interdecadal change of AO's Azores center. During 1928-1948/1975-1995 winters, the SLP anomalies of Azores high in the positive phase of AO are robust and lead to upper-level convergence anomalies, which can induce obvious significant Rossby wave source (RWS) anomalies over the Mediterranean and northeastern Atlantic. During 1905-1925/1950-1970, however, the SLP anomalies of Azores high in the positive AO phase become weaker. As a result, the convergence and RWS anomalies at upper level are mainly confined to the Mediterranean region and the associated wave activity is weaker compared with that in 1928-1948/1975-1995. Since the AO-SAT relationship has experienced two significant periods and two insignificant periods, it suggests a weakening of the AO-SAT relationship in recent two decades.