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Abstract

Interdecadal Pacific Oscillation (IPO) and the Atlantic Multidecadal Oscillation (AMO) has been found to be important to the Amundsen Sea Low (ASL) and zonally asymmetric changes in Antarctic surface air temperature that cannot be explained by anthropogenic forcing. However, most studies focus only on the joint impact of the opposite phase of AMO and IPO which prevailed during the satellite era since 1979. In this study, we utilize long-term reanalysis data to examine the effect of the four combinations of +AMO+IPO, -AMO-IPO, +AMO-IPO, and -AMO+IPO on the Antarctic surface air temperature during the past more than 100 years. During the period of +AMO+IPO and +AMO-IPO, Antarctic SAT shows an opposite distribution. And during the period of -AMO+IPO, with the exception of the Antarctic Peninsula and near the Weddell Sea, the Antarctic region as a whole is warming. The strongest signal of the SAT anomalies is for the season of austral autumn (AMJ), while the smallest magnitude compared with the other three phases is for the -AMO and -IPO. The wavetrain excited by the SST anomalies associated with IPO and AMO induces upper-level and surface atmospheric circulation anomalies, that change the SAT distribution. Also, downward longwave radiation anomalies related to the anomalous cloud cover plays a role.