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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]