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The rareness and inhomogeneity of the data points cause difficulties in the reconstruction of past average temperature. Optimal regional averaging is a method that can overcome these difficulties and obtain the average temperature of target area by means of optimal weights using limited temperature data. In this paper, the average temperature in the Northern Hemisphere is calculated by the optimal regional averaging method using two types of data: temperature data from Climatic Research Unit from 1901 to 2000 and maximum latewood density dataset of tree from 1500 to 1949. Five, ten, fifteen data points from CRU and forty data points from MXD are used in our research. The results show that even with the relatively less data used in this reconstruction, the method allows the reconstruction of the average temperature of the Northern Hemisphere more accurately, which provides the temperature information for palaeoclimate reconstruction. [ABSTRACT FROM AUTHOR]

Using XRD measurements of illite crystallinity, b values of K-rich white micas and chemical compositions of chlorites combined with homogenization temperatures of fluid inclusions in calcite, the metamorphic P- T conditions of very low-grade metapelites from different depths in the 7 km Hongcan Well 1 in the Zoigê Depression, Sichuan, China, have been obtained in this paper. Knowledge of the tectonic evolution of the studied basin allows us to derive geothermal curves for Middle and Late Triassic time (the geothermal peak) and the present day (from thermal logging of the borehole). The retrograde P- T tracks from clockwise P- T- t loops have been revealed by the plotting of individual samples on each geotherm, which can be interpreted by the lithospheric thickening due to sedimentation and folding followed by continuous uplift and erosion. A stratigraphic log indicates that the Well penetrates the steep limb of a fold which perturbed the peak geotherm and caused some P- T paths to cross. [ABSTRACT FROM AUTHOR]

Using the NCEP/NCAR and JRA-25 monthly analysis data from 1979 to 2011, this paper analyzes the interdecadal variations of winter (Dec.–Feb.) mean surface air temperature (SAT) over East Asia by means of the empirical orthogonal function (EOF) analysis method. Two dominant modes were extracted, with the leading mode basically depicting a sign consistent SAT variation and the second mode describing a meridional dipole structure between the northern and southern parts of East Asia. These two modes can explain more than 60% of the variance. The leading mode is closely related to the intensity of Siberian high and the East Asian winter monsoon. The second mode exhibits a notable interdecadal shift in the late 1990s, with a turning point around 1996/1997. Winter SAT in the northern (southern) part of East Asia tends to be cooler (warmer) since the late 1990. Winter sea level pressure (SLP) differences between 1997–2011 and 1979–1996 show negative (positive) anomalies over southern (northern) Eurasia. At 500-hPa, an anomalous blocking high occurs over northern Eurasia, while a cyclone anomaly appears over northern East Asia. In addition, the upper-level East Asian jet stream tends to shift northward and become stronger after the late 1990. Indeed, the interdecadal shift of winter SAT over East Asia is dynamical consistent with changes of the large-scale atmospheric circulation in the late 1990s. The result indicates that previous autumn sea surface temperature (SST) in the North Atlantic Ocean, the Northern Indian Ocean and the western North Pacific Ocean, as well as sea ice concentration (SIC) in the northern Eurasia marginal seas and the Beaufort Sea also experienced obvious changes in the late 1990s. In particular, the interdecadal shifts of both SST in the North Atlantic Ocean and SIC in the Arctic Ocean and its marginal seas are well coherent with that of the winter SAT over East Asia. The results indicate that the interdecadal shift of East Asian winter SAT may be related to changes in the North Atlantic SST and the Arctic SIC in the late 1990s. [ABSTRACT FROM AUTHOR]

The primary factor controlling C/C relative abundance in terrestrial ecosystem since the Last Glacial has been widely debated. Now more and more researchers recognize that climate, rather than atmospheric CO concentration, is the dominant factor. However, for a specific area, conflicting viewpoints regarding the more influential one between temperature and precipitation still exist. As temperature and precipitation in a specific area usually not only vary within limited ranges, but also covary with each other, it is difficult to get a clear understanding of the mechanism driving C/C relative abundance. Therefore, systematic analysis on greater spatial scales may promote our understanding of the driving force. In this paper, records of C/C relative abundance since the Last Glacial on a global scale have been reviewed, and we conclude that: except the Mediterranean climate zone, C plants predominated the high latitudes during both the Last Glacial and the Holocene; from the Last Glacial to the Holocene, C relative abundances increased in the middle latitudes, but decreased in the low latitudes. Combining with studies of modern process, we propose a simplified model to explain the variations of C/C relative abundance in global ecosystem since the Last Glacial. On the background of atmospheric CO concentration since the Last Glacial, temperature is the primary factor controlling C/C relative abundance; when temperature is high enough, precipitation then exerts more influence. In detail, in low latitudes, temperature was high enough for the growth of C plants during both the Last Glacial and the Holocene; but increased precipitation in the Holocene inhibited the growth of C plants. In middle latitudes, rising temperature in the Holocene promoted the C expansion. In high latitudes, temperature was too low to favor the growth of C plants and the biomass was predominated by C plants since the Last Glacial. Our review would benefit interpretation of newly gained records of C/C relative abundance from different areas and different periods, and has its significance in the understanding of the driving mechanisms of C/C variations on longer timescales (e.g., since the late Miocene) with reliable records of temperature and atmospheric CO concentration. [ABSTRACT FROM AUTHOR]

This paper describes 2007/2008 inter-annual changes in runoff from the Zhadang Glacier located on the northern slope of Nyainqêntanglha Range, Tibet, and analyzes their causes. Precipitation increased by 17.9% in summer months of 2008 compared with the same period in 2007, drainage basin runoff decreased by 33.3%, and glacial meltwater decreased by 53.8%. Change in positive accumulated air temperature explained approximately half of the inter-annual difference in glacial meltwater using a degree-day model. This suggests that the glacier is extremely sensitive to changes in air temperature. Energy balance analysis showed that change in glacier surface albedo, considered to be caused by difference in precipitation form, resulted in the large inter-annual difference in glacial meltwater. It was shown statistically that precipitation form in the summer months of 2007 was mainly rainfall which comprised 71.5% of total precipitation, while during the same period in 2008 rainfall accounted for 30.7%, with the majority of precipitation falling as snow. Precipitation form should be considered an independent factor when analyzing glacier sensitivity to climate change or forecasting the runoff from certain glaciers. [ABSTRACT FROM AUTHOR]

This paper reports a study on reconstructing temperature series for ten regions of China over the last 1000 years with a time resolution of 10 a. The regions concerned are: Northeast, North, East, South China, Taiwan, Central, Southwest, Northwest China, Xinjiang and Qinghai-Tibet Plateau. A variety of proxy data, such as ice core, tree-rings, stalagmites, peat, lake sediments, pollen and historical records, were validated with instrumental observations made in the last 120 years, and applied in the reconstruction of the temperature series. A temperature series for whole China is then established by aver- aging the ten regional series with a weighting proportional to the area of each region. Finally, temperature variations for the last 1000 years are examined, with special focus placed on the characteristics of the Medieval Warm Period (MWP), the Little Ice Age (LIA), and Modern Warming (MW). [ABSTRACT FROM AUTHOR]