ISSN 1006-9895

CN 11-1768/O4

Influence of the Antarctic Oscillation on Surface Air Temperature over the Eurasian Continent during Boreal Winter
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    Abstract:

    Based on the NCEP/NCAR daily reanalysis data over the period from 1962 to 2011, this study reveals the relationship between Antarctic Oscillation (AAO) and surface air temperature over the Eurasian continent during the boreal winter. The linear regression results show that after filtering out the El Nino-Southern Oscillation (ENSO) signal, the AAO in January is significantly and positively correlated with the air temperature over the Eurasian continent in February. When a stronger AAO occurs in January, positive geopotential height anomaly appears over the southeastern Pacific and enhances the subtropical high in the southern Hemisphere. Furthermore, it extends northward to the eastern Pacific and persists from January to February, which acts as the key circulation in the inter-hemispheric interaction. In February, the eastern Pacific geopotential height anomaly tilts northward with altitude and anchors over southwestern America in the upper troposphere, which is right at the entrance of the climatological North Atlantic storm track. The geopotential height anomaly at southwestern America is positively correlated with the transient eddy activities over the northwestern Mediterranean Sea, which can trigger a negative geopotential height anomaly over the Scandinavian. Due to the downstream dispersion of wave energy originated from the Scandinavian geopotential height anomaly, positive anomaly develops to the west of the Lake Baikal and the negative phase of the Scandinavian pattern forms with increased westerlies around 60°N. The increased westerlies can suppress the southward invasion of cold air and thus are favorable for the development and maintenance of above-normal temperature over Eurasian continent, and vice versa.

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History
  • Received:September 12,2016
  • Revised:
  • Adopted:
  • Online: July 11,2017
  • Published: