On the Nature of the Arctic Oscillation and Its Diverse Influence on Surface Temperature

Abstract:

What physical process that the Arctic oscillation (AO) describes is still unclear and under debate since Thompson and Wallace’s pioneering work. By applying a cluster analysis to daily NCEP/NCAR reanalysis data, present study found that the AO pattern can be resolved into two families with five family members and each member has a timescale of one week or so. One family takes a form of mixed NAO and Pacific center, and another takes a form of double-wavetrain which has a projection of PNA over Pacific-North America and of NAO over North Atlantic. Different family members have different influence on northern Hemisphere surface temperature, which should be taken into consideration when one makes weather prediction based on AO. Due to the projection of family members on PNA and NAO, AO shows somehow correlation with PNA or NAO. It is also shown that one of the members is strongly modulated by the El Nino-Southern oscillation (ENSO) and shows an upward (downward) trend in its frequency of occurrence between 1958-2005.