1 3 DOI 10.1007/s00382-015-2574-5 Clim Dyn Is the interdecadal variation of the summer rainfall over eastern China associated with SST? Dong Si 1,2 · Zeng-Zhen Hu 3 · Arun Kumar 3 · Bhaskar Jha 3,4 · Peitao Peng 3 · Wanqiu Wang 3 · Rongqing Han 1 Received: 4 November 2014 / Accepted: 16 March 2015 © Springer-Verlag Berlin Heidelberg 2015 Keywords Interdecadal variation · Eastern China · Summer rainfall · SST · AGCM · Atmospheric internal dynamics 1 Introduction With the increase of the observed record length and rapid development in climate models, the understanding of the interdecadal time scale climate variation has improved con- siderably, particularly, for the interdecadal variations in the twentieth century. For example, a remarkable interdecadal shift was observed in the late 1970s. Numerous studies revealed that this interdecadal shift may be associated with tropical Pacific sea surface temperature (SST) forcing (Gra- ham et al. 1994). Since the late 1970s, SSTs in the tropical eastern and central Pacific have increased, and the Pacific North America (PNA) teleconnection pattern has strength- ened during the same time (Nitta and Yamada 1989). The atmospheric general circulation model (AGCM) forced by observed SST reproduced the interdecadal variation of the atmospheric circulation in the Northern Hemisphere (NH) in the late 1970s (Graham 1994), suggesting the important role of SST in the interdecadal climate variations. It is now well established that the link between the interdecadal vari- ation of the atmospheric circulation in NH and the tropical Pacific SST is primarily the tropical-mid-latitude telecon- nection (Trenberth 1990; Trenberth and Hurrell 1994; Gra- ham et al. 1994). On regional scale, climate over eastern China that is greatly influenced by the NH atmospheric circulation also exhibits remarkable interdecadal characteristics. For example, the temperature and rainfall over eastern China had obvious decadal (10–14 years) and interdecadal (30–40 years) time scale variations (Wang et al. 2005). Abstract The present study examined the major features of the interdecadal variation of the summer rainfall over eastern China (IVRC) and the possible association with sea surface temperature (SST). We noted that the first leading mode of IVRC (accounting for nearly half of the total vari- ance and with maximum loading for the summer rainfall anomalies over South China) may be not forced by SST. On the other hand, the second and third leading modes [accounting for 17.1 and 13.6 % of the total variance and mainly associated with the summer rainfall anomalies over the Yangtze River valley (YRV) and North China, respec- tively] in some extent are forced by SST anomalies. These observational results are confirmed by atmospheric general circulation model (AGCM) simulations forced by observed SST. By eliminating the internal dynamical process driven rainfall though ensemble mean, the simulations further sug- gest an overall enhancement of the intensity of IVRC in the corresponding ensemble mean, especially in the YRV and North China regions, but not in South China. That implies the different role of SST in driving IVRC over different regions. * Dong Si sidong@cma.gov.cn 1 National Climate Center, China Meteorological Administration, No. 46 Zhongguancun South Street, Haidian District, Beijing 100081, China 2 Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China 3 Climate Prediction Center, NCEP/NOAA, College Park, MD, USA 4 INNOVIM, LLC, Greenbelt, MD, USA