Studies of the impacts of the Tibetan Plateau (TP) on climate in China in the last four years are reviewed. It is reported that temperature and precipitation over the TP have increased during recent decades. From satellite data analysis, it is demonstrated that most of the precipitation over the TP is from deep convection clouds. Moreover, the huge TP mechanical forcing and extraordinary elevated thermal forcing impose remarkable impacts upon local circulation and global climate. In winter and spring, stream flow is deflected by a large obstacle and appears as an asymmetric dipole, making East Asia much colder than mid Asia in winter and forming persistent rainfall in late winter and early spring over South China. In late spring, TP heating contributes to the establishment and intensification of the South Asian high and the abrupt seasonal transition of the surrounding circulations. In summer, TP heating in conjunction with the TP air pump cause the deviating stream field to resemble a cyclonic spiral, converging towards and rising over the TP. Therefore, the prominent Asian monsoon climate over East Asia and the dry climate over mid Asia in summer are forced by both TP local forcing and Eurasian continental forcing. Due to the longer memory of snow and soil moisture, the TP thermal status both in summer and in late winter and spring can influence the variation of Eastern Asian summer rainfall. A combined index using both snow cover over the TP and the ENSO index in winter shows a better seasonal forecast. On the other hand, strong sensible heating over the Tibetan Plateau in spring contributes significantly to anchor the earliest Asian monsoon being over the eastern Bay of Bengal (BOB) and the western Indochina peninsula. Qualitative prediction of the BOB monsoon onset was attempted by using the sign of meridional temperature gradient in March in the upper troposphere, or at 400 hPa over the TP. It is also demonstrated by a numerical experiment and theoretical study that the heating over the TP lea 相似文献
Seaweeds cultivation has resulted in great achievements, although it has a history of only a few decades. With higher productivity and resulting higher profit, it has become the leading marine exploitation industry with the brightest prospects. The relatively limited species introduced for commercial cultivation showed great biological diversity. Introduction of selected good strains for traditional cultivation and the transformation from cultivation of mixed strains to that of pure cell lines are two certain tendencies in the future. Pure line cultivation of seaweeds in a sort of advanced biotechnology. It provides new opportunities for not only the industry itself, but also the stable market of high quality natural marine products. More work should be done on principles and methods to obtain optimal results from the combination of pure line cultivation techniques with advanced biochemistry. The programmed batch production of fine chemicals such as polysaccharides and proteins will probably become the social demand.
The source of elements and the modern sedimentary environment of the ferromanganese nodules enriched area of the North Pacific
region were analysed statistically and discussed in detail. Cluster analysis shows the area's surface sediments are mainly
brown clay and biogenic calcareous, calcsiliceous and siliceous ooze. Factor (principal component) analysis shows that the
area's trace elements (Fe, Mn, Cu, Co, Ni, Zn, Cr, etc.) mainly come through adsorption of clay minerals and secondarily from
authigenic sediments related to biochemical processes.
Bao Gende, 1990. Characteristics of element geochemistry in sediments in the ferromanganese nodules enriched area of the North
Pacific region.Acta Sedimentologica Sinica. (in press, in Chinese) 相似文献
Using photospheric vector magnetograms of the Huairou Solar Observing Station and coronal X-ray images from the Yohkoh Soft X-Ray Telescope, we calculate the helicity patterns of 43 pairs of active regions and the chirality of 50 pairs of opposite
magnetic polarity regions that are connected by transequatorial loops (TLs). To make the results more convincing, two helicity
proxies including the local current helicity hc and the force-free factor αbest are computed. The results, which are similar for both parameters, are as follows: (1) Current helicity of the active regions
pairs connected by transequatorial loops have no obvious regularity: About 50% of the active region pairs carry the same current
helicity sign and about 50% of them have the opposite. (2) If we consider the magnetic polarity pairs connected by the TLs,
the result is almost the same as that for the active region pairs, with a little more than half of them showing the same chirality.
We also make linear force-free extrapolations for 33 TLs and determine their force-free parameter α by comparing extrapolated field lines to X-ray images of the TLs. Out of the 19 cases when the footpoints of the TLs have
the same current helicity sign, we find that the sign of α of the TLs is the same as the sign of the current helicity in the footpoints in 12 cases, whereas it is of opposite sign
in 4 cases, and in 3 cases the TLs were found to be potential. 相似文献