The Significant Relationship between the Arctic Oscillation (AO) in December and the January Climate over South China |
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Authors: | YANG Hui |
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Institution: | State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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Abstract: | Using NCEP/NCAR reanalysis data, the China rainfall and surface
temperature data of the China Meteorological Administration, and the Arctic
Oscillation (AO) indices of NOAA, the author investigates relationships between
the AO and the precipitation and temperature over China. There exists a good
relationship between the AO index in December and the succeeding January
precipitation over South China, indicating that when the December AO index is
positive (negative), the January precipitation over South China increases
(decreases). A remarkable negative correlation between the December AO index
and the January surface temperature also exists over South China, indicating
that when the December AO index is positive (negative), the January temperature
over South China drops (rises). The occurrence of this anomalous climate is
related to the anomalies of the atmospheric circulation systems. The December
AO greatly influences circulation anomalies in January. A positive phase of the
AO is found to lead to a stronger subtropical jet over the south side from the
Iran Plateau to the Tibetan Plateau. Consequently, it results in a deepening
pressure trough around the Bay of Bengal, which transports the warm and wet air
to South China continuously. The Siberian High in January is stronger and
extends farther southeastward. It results in continual cold air at 1000 hPa
pouring into South China, inducing low temperature. Cooperating with the trough
of the Bay of Bengal, anomalous precipitation occurs over South China. For the
negative phase of the December AO, the opposite situation is observed. |
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Keywords: | Arctic Oscillation precipitation surface temperature large-scale circulation |
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