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| The Leading Mode of Wintertime Cold Wave Frequency in Northern China during the Last 42 Years and Its Association with Arctic Oscillation |
| WEI Jun-Hong,LIN Zhao-Hui |
| International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029；Graduate University of Chinese Academy of Sciences, Beijing 100049,International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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Abstract This study examined wintertime (NovemberApril) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature from 280 stations across northern China and European Centre for Medium-Range Weather Forecasts (ECMWF) 40-Year Re-analysis ERA-40 data. The leading empirical orthogonal function EOF mode of wintertime CWF (CWF-EOF1) indicates an identical signal over most northern China, with the characteristic trend of linear decline for the leading principal component (CWF-PC1). After the linear trend is removed, remarkable inter-annual variability is found to be the dominant feature of the CWF-PC1. The regression map for sea level pressure based on CWF-PC1 corresponds to the negative phase of AO. Correlation analysis further proves that CWF-PC1 has a significant negative correlation with AO at the inter-annual time scale. The relationship between AO and global surface air temperature is also investigated in order to understand its association with cold air activity over East Asia, and it is suggested that the anomalies of atmospheric circulation in Siberia may serve as a bridge for interaction between AO and CWF in northern China during wintertime.
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Received: 03 March 2009
Revised: 03 April 2009
Accepted: 18 April 2009
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