Abstract: On the basis of the daily air surface temperature data of 468 meteorological observation stations in mainland China from 1960 to 2013, the spatial and temporal characteristics of winter temperature are analyzed. First, linear regression and regime shift detection methods are used to identify tendency and abrupt point. Winter temperature shows interdecadal variability superimposed on a long-term warming trend with the cold period from 1960-1961 to 1985-1986, the warm period from 1986-1987 to 2005-2006, and the hiatus period from 2006-2007 to 2012-2013.
To examine the underlying mechanism for the formation of the three periods, the atmospheric circulation systems are compared by using National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. It is found that the cold/hiatus (warm) period is characterized by weak (strong) zonal wind in the middle and high latitudes of the Northern Hemisphere, strong (weak) East Asian Trough on the 500 hPa geopotential height field, strong (weak) downdraft after the trough, strong (weak) Siberian High, and enhanced (weakened) northeast surface wind over the Asian continent. These features provide favorable circulation conditions for cold (warm) winter in mainland China. Furthermore, by influencing the East Asian winter monsoon circulation, the Northern Hemisphere Annular Mode/Arctic Oscillation (NAM/AO) affects the winter temperature, particularly the winter minimum temperature on the interdecadal timescale.
Conversely, the Pacific Decadal Oscillation (PDO) is positively correlated to the winter temperature on the interdecadal timescale. Subsequently, the results indicate that with the modulation of the interdecadal variability of the PDO, the combined effects of NAM/AO and El Niño Southern Oscillation (ENSO) influence the first EOF mode (EOF1), which has an identical signal throughout China, and influences the second EOF mode (EOF2), which has a seesaw pattern between southern and northern China. In addition, the superimposition of EOF1 and EOF2 probably caused persistent warming winters in the 1980s and 1990s and may have been responsible for the significant cooling trend during the last seven years in northwestern and northeastern China.