Based on the daily rainfall datasets of 743 stations in China and the NCEP/NCAR monthly reanalysis data during the period of 1960-2003,the relationship between the anomalous extreme precipitation(EP) in the south of China and atmospheric circulation in the Southern Hemisphere is analyzed.The phenomenon of opposite changes in the sea level pressure and geopotential height anomalies over the Ross Sea and New Zealand is defined as RN,and the index which describes this phenomenon is expressed as RNI.The results show that the RN has barotropic structure and the RNI in May is closely related to the June EP amount in the south of China(SCEP) and the East Asian summer monsoon(EASM).The positive correlations between the May RNI at each level and the June SCEP are significant,and the related simultaneous correlations between the RNI and the June SCEP are also positive,suggesting that the potential impact of RN on the SCEP persists from May to June.Therefore,RN in May can be taken as one of the predictive factors for the June SCEP.Furthermore,one possible physical mechanism by which the RN affects the June SCEP is a barotropic meridional teleconnection emanating from the Southern Hemisphere to the western North Pacific.
Using Lanczos filtered simulation results from the ECHO-G coupled ocean-atmosphere model,this study analyzes the spatiotemporal structure of temperature and precipitation on centennial time scale to examine how climate change in eastern China responded to external forcing during the last millennium.The conclusions are (1) eastern China experienced a warm-cold-warm climate transition,and the transition from the warm period to the cold period was slower than the cold to warm transition which followed it.There was more rainfall in the warm periods,and the transitional peak and valley of precipitation lag those of temperature.The effective solar radiation and solar irradiance have significant impacts on the temporal variation of both temperature and precipitation.Volcanic activity plays an important role in the sudden drop of temperature before the Present Warm Period (PWP).There is a positive correlation between precipitation and volcanic activity before 1400 A.D.,and a negative relationship between the two thereafter.The concentration of greenhouse gases increases in the PWP,and the temperature and precipitation increase accordingly.(2) The spatial pattern of the first leading empirical orthogonal function (EOF) mode of temperature on centennial time scale is consistent with that on the inter-annual/inter-decadal (IA-ID) time scales;namely,the entirety of eastern China is of the same sign.This pattern has good coherence with effective solar radiation and the concentrations of greenhouse gases.The first leading EOF mode of precipitation on centennial time scale is totally different from that on the IA-ID time scales.The first leading mode of centennial time scale changes consistently over the entirety of eastern China,while the middle and lower reaches of the Yangtze and Yellow Rivers are the opposite to the rest of eastern China is the leading spatial pattern on IA-ID time scale.The distribution of precipitation on centennial time scale is affected by solar irradiance and greenhouse gas concentrations.
WANG HongLiLIU JianWANG ZhiYuanWANG SuMinKUANG XueYuan
This paper investigates the interannual variation of the West Pacific Subtropical High(WPSH) intensity based on the data compiled by the Chinese National Climate Center.Monthly reanalysis data from National Centers for Environmental Prediction and National Center for Atmospheric Research(NCEP/NCAR) are also used to study the lead-lag relationship between WPSH intensity and surface heat flux anomalies.The three major findings are as follows:First,WPSH intensity presents good seasonal persistence,especially from winter to the ensuing summer.Persistence is more significant after 1977,especially from spring to summer,and from summer to autumn;persistence of anticyclonic anomalies are significantly better than cyclonic anomalies.Second,surface heat flux tends to present opposite anomalous patterns between the strong and weak years of the WPSH intensity,which is especially valid at the latent heat flux over the ocean.Simultaneous correlations between surface heat flux and WPSH intensity in each of the seasons are marked by similar key areas.Finally,surface heat flux from the preceding winter of a strong summer WPSH is quite similar to strong spring WPSH,but the positive anomalies over the northwest Pacific and south of Japan are notably stronger.The situations in the weak years are similar except for those over the northwest Pacific:winter surface heat flux shows negative anomalies for a weak spring WPSH,but positive anomalies for a weak summer WPSH.It is suggested that surface heat flux in the previous winter plays an important role in maintaining the WPSH intensity in the ensuing spring and summer.
Three global datasets, the History Database of the Global Environment （HYDE）, Kaplan and Krurnhardt （KK） and Pongratz of reconstructed anthropogenic land cover change （ALCC） were introduced and compared in this paper. The HYDE dataset was recon- structed by Goldewijk and his colleagues at the National institute of Public ttealth and the Environment in Netherland, covering the past 12 000 years. The KK dataset was reconstructed by Kaplan and his colleagues, the Soil-Vegetation-Atmosphere Research Group at the Institute of Environmental Engineering in Switzerland, covering the past 8000 years. The Pongratz dataset was reconstructed by Pon- gratz and her colleagues at the Max Planck Institute for Meteorology in Germany, coveting AD 800-1992. The results show that the reconstructed datasets are quite different from each other due to the different methods used. The three datasets all allocated the historical ALCC according to human population density. The main reason causing the differences among the three datasets lies on the different relationships between population density and land use used in each reconstructed dataset. The KK dataset is better than the other two datasets for two important reasons. First, it used the nonlinear relationship between population density and land use, while the other two used the linear relationship. Second, Kaplan and his colleagues adopted the technological development and intensification parameters and considered the wood harvesting and the long-term fallow area resulted from shifting cultivation, which were neglected in the recon- structions of the other two datasets. Therefore, the KK dataset is more suitable as one of the anthropogenic forcing fields for climate simulation over the past two millennia that is recently concerned by two projects, the National Basic Research Program and the Strategic and Special Frontier Project of Science and Technology of the Chinese Academy of Sciences.
YAN MiWANG ZhiyuanJed Oliver KAPLANLIU JianMIN ShenWANG Sumin
