An atmospheric origin of the multi-decadal bipolar seesaw.
A prominent feature of recent climatic change is the strong Arctic surface warming that is contemporaneous with broad cooling over much of Antarctica and the Southern Ocean. Longer global surface temperature observations suggest that this contrasting pole-to-pole change could be a manifestation of a multi-decadal interhemispheric or bipolar seesaw pattern, which is well correlated with the North Atlantic sea surface temperature variability, and thus generally hypothesized to originate from Atlantic meridional overturning circulation oscillations. Here, we show that there is an atmospheric origin for this seesaw pattern. The results indicate that the Southern Ocean surface cooling (warming) associated with the seesaw pattern is attributable to the strengthening (weakening) of the Southern Hemisphere westerlies, which can be traced to Northern Hemisphere and tropical tropospheric warming (cooling). Antarctic ozone depletion has been suggested to be an important driving force behind the recently observed increase in the Southern Hemisphere's summer westerly winds; our results imply that Northern Hemisphere and tropical warming may have played a triggering role at an stage earlier than the first detectable Antarctic ozone depletion, and enhanced Antarctic ozone depletion through decreasing the lower stratospheric temperature.
1] Polar Climate System and Global Change Laboratory, Nanjing University of Information Science and Technology, Nanjing, China. 210044 [2] Earth System Modelling Center (ESMC), Nanjing International Academy of Meteorological Sciences(NIAMS), Nanjing University of Information Science and Technology, Nanjing, China. 210044.
Zhaomin
Z
Wang
International Arctic Research Center and Department of Atmospheric Sciences, University of Alaska Fairbanks, 930 Koyukuk Dr., Fairbanks, Alaska 99775, USA.
Xiangdong
X
Zhang
Polar Climate System and Global Change Laboratory, Nanjing University of Information Science and Technology, Nanjing, China. 210044.
Zhaoyong
Z
Guan
Polar Research Institute of China, No. 451 Jinqiao Road, Pudong District, Shanghai. 200136, China.
Bo
B
Sun
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
Xin
X
Yang
1] Polar Climate System and Global Change Laboratory, Nanjing University of Information Science and Technology, Nanjing, China. 210044 [2] Earth System Modelling Center (ESMC), Nanjing International Academy of Meteorological Sciences(NIAMS), Nanjing University of Information Science and Technology, Nanjing, China. 210044.
Chengyan
C
Liu