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71.
An introduction to the
instrumonts to be used for solar radio observations in Beijing in Solar Cycle 23 is made
in this paper. They are 10cm solar radio telescope which has been used for a long time,and 1.0~2.0GHz,2.6~3.8GHz and 5.2~7.6GHz spectrometers. The former two spectrometers has
passed a test,showing
high guality,and the
5.2~7.6GHz one will
be in operation from 1999. It is believed that highl gualified data should be obtained in
the next solar cycle. 相似文献
72.
利用神经网络和粗糙集处理不确定性问题的优势,提出一种粗糙集结合神经网络进行森林火灾预测模型。通过与传统预测模型相比较,证明了该方法的有效性。 相似文献
73.
74.
陕北春季森林火灾气象条件分析 总被引:2,自引:0,他引:2
通过对1989~2004年间陕北春季森林火灾发生期气象资料进行研究分析,指出春季2~5月份林火期气候特征、森林火灾易发期天气环流特征,林火的发生与冷空气活动密切相关。在春季森林火灾期地面气象要素也呈现出一定的变化规律。 相似文献
75.
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77.
In this article, Milkov and Sassen’s model is selected to calculate the thickness of the gas hydrate stable zone (GHSZ) and the amount of gas hydrate in the Xisha (西沙) Trough at present and at the last glacial maximum (LGM), respectively, and the effects of the changes in the bottom water temperature and the sea level on these were also discussed. The average thickness of the GHSZ in Xisha Trough is estimated to be 287 m and 299 m based on the relationship between the GHSZ thickness and the water depth established in this study at present and at LGM, respectively. Then, by assuming that the distributed area of gas hydrates is 8 000 km2 and that the gas hydrate saturation is 1.2% of the sediment volume, the amounts of gas hydrate are estimated to be ~2.76×1010 m3 and ~2.87×1010 m3, and the volumes of hydrate-bound gases are ~4.52×1012 m3 and ~4.71×1012 m3 at present and at LGM, re- spectively. The above results show that the thickness of GHSZ decreases with the bottom water tem- perature increase and increases with the sea level increase, wherein the effect of the former is larger than that of the latter, that the average thickness of GHSZ in Xisha Trough had been reduced by ~12 m, and that 1.9×1011 m3 of methane is released from approximately 1.1×109 m3 of gas hydrate since LGM. The released methane should have greatly affected the environment. 相似文献
78.
Instability characteristics of the East Asian Monsoon recorded by high-resolution loess sections from the last interglacial (MIS5) 总被引:3,自引:0,他引:3
Guan QingYu Pan BaoTian Gao HongShan Li BingYuan Wang JunPing Su Huai 《中国科学D辑(英文版)》2007,50(7):1067-1075
The selection of high-resolution loess sections is needed in order to determine the climatic variability of the East Asian Monsoon during the last interglacial. Two sequences of S1 on the eastern and west-ern sides of the Liupan Mountain were both composed of five paleosol layers and four loess layers,indicating that there were five strong summer monsoon events and four strong winter monsoon events in MIS5. This corresponds with other records of the East Asian Monsoon,along with NGRIP and the North Atlantic records,implying that the climate of the Northern Hemisphere was very instable during the last interglacial. Two layers of paleosols and one layer of loess had developed during MIS5a and MIS5c. Compared with MIS5e,the climate in MIS5a and MIS5c fluctuated more intensively on a millen-nial scale,whereas the climate was relatively stable in MIS5e. 相似文献
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