Interannual Climate Variability Change during the Medieval Climate Anomaly and Little Ice Age in PMIP3 Last Millennium Simulations

In this study, we analyzed numerical experiments undertaken by 10 climate models participating in PMIP3（Paleoclimate Modelling Intercomparison Project Phase 3） to examine the changes in interannual temperature variability and coefficient of variation（CV） of interannual precipitation in the warm period of the Medieval Climate Anomaly（MCA） and the cold period of the Little Ice Age（LIA）. With respect to the past millennium period, the MCA temperature variability decreases by 2.0% on average over the globe, and most of the decreases occur in low latitudes. In the LIA, temperature variability increases by a global average of 0.6%, which occurs primarily in the high latitudes of Eurasia and the western Pacific. For the CV of interannual precipitation, regional-scale changes are more significant than changes at the global scale, with a pattern of increased（decreased） CV in the midlatitudes of Eurasia and the northwestern Pacific in the MCA（LIA）. The CV change ranges from-7.0% to 4.3%（from -6.3% to 5.4%）, with a global average of -0.5%（-0.07%） in the MCA（LIA）.Also, the variability changes are considerably larger in December–January–February with respect to both temperature and precipitation.

Interannual Variability of the Normalized Difference Vegetation Index on the Tibetan Plateau and Its Relationship with Climate Change

The Qinghai-Xizang Plateau, or Tibetan Plateau, is a sensitive region for climate change, where the manifestation of global warming is particularly noticeable. The wide climate variability in this region significantly affects the local land ecosystem and could consequently lead to notable vegetation changes. In this paper, the interannual variations of the plateau vegetation are investigated using a 21-year normalized difference vegetation index （NDVI） dataset to quantify the consequences of climate warming for the regional ecosystem and its interactions. The results show that vegetation coverage is best in the eastern and southern plateau regions and deteriorates toward the west and north. On the whole, vegetation activity demonstrates a gradual enhancement in an oscillatory manner during 1982-2002. The temporal variation also exhibits striking regional differences： an increasing trend is most apparent in the west, south, north and southeast, whereas a decreasing trend is present along the southern plateau boundary and in the central-east region. Covariance analysis between the NDVI and surface temperature/precipitation suggests that vegetation change is closely related to climate change. However, the controlling physical processes vary geographically. In the west and east, vegetation variability is found to be driven predominantly by temperature, with the impact of precipitation being of secondary importance. In the central plateau, however, temperature and precipitation factors are equally important in modulating the interannual vegetation variability.

The Interannual Variability of Climate in a Coupled Ocean-Atmosphere Model

In this paper, the interannual variability simulated by the coupled ocean-atmosphere general circulation modelof the institute of Atmospheric Physics (IAP CGCM) in 40 year integrations is analyzed, and compared with that bythe corresponding IAP AGCM which uses the climatic sea surface temperature as the boundary condition in 25 yearintegrations.The mean climatic states of January and July simulated by IAP CGCM are in good agreement with that by IAPAGCM, i.e., no serious 'climate drift' occurs in the CGCM simulation. A comparison of the results from AGCM andCGCM indicates that the standard deviation of the monthly averaged sea level pressure simulated by IAP CGCM ismuch greater than that by IAP AGCM in tropical region. In addition, both Southern Oscillation (SO) and NorthAtlantic Oscillation (NAO) can be found in the CGCM simulation for January, but these two oscillations do not existin the AGCM simulation.The interannual variability of climate may be classified into two typest one is the variation of the annual mean,another is the variation of the annual amplitude. The ocean-atmosphere interaction mainly increases the first type ofvariability. By means of the rotated EOF, the most important patterns corresponding to the two types of interannualvariability are found to have different spatial and temporal characteristics.

Interannual Changes of Land Surface Radiation Components in Loess Plateau and Their Responses to Climate Change

In this paper,land surface observation data at semi-arid climate and environmental observation station（ SACOL station） of Lanzhou University during 2006- 2012 and the data of Yuzhong meteorological station were used to analyze the responses of land surface radiation budget components to climate fluctuation,study the interannual variability of surface albedo,and discuss the feedback of various land surface process parameters on the interannual fluctuations of temperature and precipitation in Loess Plateau. According to the type of precipitation in Loess Plateau,the year was divided into winter and summer in order to get more significant interannual variability and correlation. The results showed that the trends of temperature and precipitation during 2006- 2012 were consistent with the warming and drying total trend in recent years in Loess Plateau. Shallow surface soil moisture and temperature showed a good response to temperature and precipitation,and the annual variation of summer half year had greater impact on the trend in the whole year. Incident solar radiation increase was major reason for climate warming in the Loess Plateau region.The combined effect of climatic factors was the reason for the change of surface albedo. Through the distinguish inquiry by winter and summer data,it was obtained that most correlations between summer radiation components and climatic factors have been improved,and partial correlations between winter radiation components and climatic factors have been increased.