1990年代初中国气温变化的年代际转折及与地表太阳辐射变化的可能 .pptVIP

1990年代初中国气温变化的年代际转折及与地表太阳辐射变化的可能联系 钱诚1, 符淙斌2,1, Zhaohua Wu3 Background The annual cycle is the dominant component for many climate variables outside the tropics and the most prominent climate oscillation. However, to date only a limited number of analyses have been reported concerning its variability and changes, especially in the seasonality of surface air temperature (SAT), under a changing climate in contrast to the numerous studies focusing on long-term global or regional warming. This is partly because the annual cycle of a climate variable, which is traditionally assumed repetitive from year to year and estimated by averaging the values of that variable for the same day/month over a period of several years, is frequently removed in studies concerning climate variability or changes. BackgroundChoice of base period/mean annual cycle for calculating anomaly Definition of El Ni?oSensitive to the choice of base period/mean annual cycle Background Several observational analyses have reported that the amplitude of the annual cycle of land SAT decreases (weakening seasonality) (e.g., Thomson 1995; Stine et al. 2009) in much of the Northern Hemisphere (NH) during global warming. However, the causes and significance of these observed changes remain poorly understood (Stine et al. 2009): Warming trend/increasing atmospheric CO2 concentration (e.g.Thomson 1995) internal atmospheric variability, e.g. the North Atlantic Oscillation (e.g. Zveryaev 2007) or the northern annular mode (Stine et al. 2009). China is one of the ideal countries for studying changes in the annual cycle and whether they are related to a warming tendency or to an increasing atmospheric CO2 concentration Its annual cycle is dominant Its warming rate is more rapid than global mean or NH mean temperature over the past 5 decades (Ren et al. 2005) It has plenty of meteorological observations Data an updated homogenized daily mean/maximum/minimum surface air temperature dataset, which is based on