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WANG Shuang, WU Qigang, LIU Shizuo, et al. 2022. Impacts of Antarctic Sea Ice Oscillation on Summer Atmospheric Circulation in the Northern Hemisphere [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 46(6): 1349−1365. doi: 10.3878/j.issn.1006-9895.2111.21051
Citation: WANG Shuang, WU Qigang, LIU Shizuo, et al. 2022. Impacts of Antarctic Sea Ice Oscillation on Summer Atmospheric Circulation in the Northern Hemisphere [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 46(6): 1349−1365. doi: 10.3878/j.issn.1006-9895.2111.21051

Impacts of Antarctic Sea Ice Oscillation on Summer Atmospheric Circulation in the Northern Hemisphere

  • The primary mode of empirical orthogonal function of Antarctic sea ice is a dipole anomaly, with the positive and negative anomaly centers over the Bellingshausen/Amundsen Sea and the Weddell Sea, respectively. This dipole anomaly is known as the Antarctic sea ice oscillation or Antarctic dipole. Previous studies have shown that the Antarctic sea ice oscillation in austral winter and spring has a significant effect on the subsequent Antarctic oscillation (AAO)-type atmospheric circulation, which significantly impacts the Northern Hemisphere climate and East Asian summer monsoon. This empirical study further examines the remote effects of the May–June–July (MJJ) Antarctic sea ice oscillation on the boreal summer atmospheric circulation in the Northern Hemisphere and the associated physical processes. Results showed that the Antarctic sea ice dipole anomaly has good persistence around austral winter from MJJ to July–August–September, which triggers persistent AAO-like atmospheric responses in the troposphere and lower stratosphere with the increase in the pressure gradient between middle and high latitudes. Moreover, the latitudinal mean zonal wind exhibits a significant distribution of meridional teleconnection from the South Pole to the North Pole. In the middle troposphere, the 700-hPa geopotential height field exhibits significant negative anomalies from northern Australia to the maritime continent, a significant positive anomaly center near Japan, and a band-shaped negative anomaly near the Sea of Okhotsk and the Aleutian Islands when the atmosphere lags behind the sea ice anomaly by 0 to 2 months. It is another form of meridional teleconnection, except for the zonal wind. Significant negative precipitation and sea surface temperature anomalies are detected in the equatorial central Pacific and the Indian Ocean, and significant positive precipitation anomalies from the northern Maritime Continent to eastern coastal China. Furthermore, the negative geopotential height anomaly from the subtropical North America to the western Atlantic and the positive geopotential height anomaly center over the North Atlantic constitute a structure similar to the western Atlantic (WA) teleconnection. Significant positive precipitation anomalies in the tropical southern Atlantic and negative precipitation anomalies over the Sahara are detected. In terms of the physical mechanism, the Antarctic sea ice dipole first affects the Ferrel circulation through local forcing effects. In turn, the ascending branch of Hadley circulation over the oceanic continental region and Tropical Atlantic is enhanced by the meridional circulation adjustment. Then, the negative phase of the Pacific Japan wave train and WA teleconnection excited by the enhanced tropical convection affects the atmospheric circulation in the Northern Hemisphere. The strong tropical convection activity in the oceanic continental region (particularly near the Philippines) and Tropical Atlantic serves as a bridge to transmit the forced tropical signals to boreal summer East Asia–North Pacific, North Atlantic–Europe, and other middle-latitude and high-latitude regions in the Northern Hemisphere. These results indicate that the persistent Antarctic sea ice oscillation anomaly from MJJ to August–September–October has significant impacts on the summer atmospheric circulation in the tropics and Northern Hemisphere.
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