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381.
现代冰川过程与全球环境气候演变 总被引:3,自引:0,他引:3
文章从宏观和微观两个方面扼要阐述了现代冰川过程与全球变化之间的关系。南极冰盖和格陵兰冰盖冰川物质平衡值目前还没有确切结论,虽然它与全球海平面的升降密切相关。山地冰川末端进退变化和冰川物质平衡与全球升温对应较好。极地冰盖现代降水中的稳定同位素比率,主要阴、阳离子、生物有机酸、微粒、超痕量重金属元素、宇宙尘埃以及火山灰等杂质的含量,为认识地球现代环境气候状况提供了丰富的资料。极地冰盖冰芯的分析结果为重建过去气候环境提供了大信息量,高保真度和高分辨率的资料为预测未来气候环境奠定了坚实基础,具有其它任何载体无法取代的优越性。山地冰川的现代和过去气候环境记录,对研究全球和区域性气候环境状况与变迁意义重大 相似文献
382.
本文利用1991年度南极中山站的地磁资料,分析研究极夜(5、6、7月)及极昼(11、12月)期间S、SD的变化特征。研究结果表明,H、D、Z三个分量的S、SD在极夜期间的变化幅度都小于极昼期间的变化幅度,S在世界时UT6时左右出现极值。这是由于在5、6、7月的太阳直射点在北半球,太阳紫外辐射和X射线辐射减少,在11、12月太阳的直射点在南半球,太阳紫外线和X射线辐射增大,致使空间电高层等效电流发生变化所产生。 相似文献
383.
日本兵库县南部地震调查与中国唐山大地震的比较 总被引:1,自引:0,他引:1
叙述了1995年1月日本兵库县南部地震的强地面运动特征,并与1976年中国唐山地震的地面运动特征进行了对比,讨论了日本地震后次生灾害——火灾的残酷性,并分析了该次地震的前兆现象 相似文献
384.
浅谈建筑物加层中的抗震问题 总被引:1,自引:0,他引:1
叙述了建筑物增层的现实情况,提出建筑物尤其是处于地震重点监视防御区的建筑物增层时,必须考虑建筑物的场地、结构、材料等抗震因素。 相似文献
385.
386.
湘中南花岗岩类地质时代分析 总被引:1,自引:0,他引:1
本文利用花岗岩形成时,在围岩岩层上保留一定的构造形迹来判别花岗岩形成方式和时代,为确定花岗岩形成时代开辟了一条简便的途径。 相似文献
387.
H. A. Bridgman R. C. Schnell G. A. Herbert B. A. Bodhaine S. J. Oltmans 《Journal of Atmospheric Chemistry》1989,9(1-3):49-70
In April 1986, a well-instrumented NOAA WP-3D research aircraft conducted three flights in the Canadian Arctic tied to the Canadian Atmospheric Environment Service baseline station in Alert, Northwest Territories. Two of the flights were coordinated with the National Aeronautical Establishment of Canada Twin Otter and the University of Washington C-131 research aircraft. The haze observed in the Canadian Arctic was well-aged and mixed throughout the troposphere in concentrations well below those observed during the previous weeks in the Alaskan Arctic. Over the ice, beneath the surface temperature inversion, ozone was generally depleted to near zero. Over the coast at Alert, there is evidence that topography and downslope winds reduce the strength of the inversion, thus allowing lower tropospheric gases and aerosols to mix down to the surface. At the top of the troposphere, an aerosol-depleted region was observed. In the lower stratosphere, aerosol concentrations were elevated above those observed in the troposphere. 相似文献
388.
V. Kudielka 《Celestial Mechanics and Dynamical Astronomy》1994,60(4):455-470
An analytic model for third-body perturbations and for the second zonal harmonic of the central body's gravitational field is presented. A simplified version of this model applied to the Earth-Moon-Sun system indicates the existence of high-altitude and highly-inclined orbits with their apsides in the equator plane, for which the apsidal as well as the nodal motion ceases. For special positions of the node, secular changes of eccentricity and inclination disappear too (balanced orbits). For an ascending node at vernal equinox, the inclination of balanced orbits is 94.56°, for a node at autumnal equinox 85.44°, independent of the eccentricity of the orbit. For a node perpendicular to the equinox, there exist circular balanced orbits at 90° inclination. By slightly adjusting the initial inclination as suggested by the simplified model, orbits can be found — calculated by the full model or by different methods — that show only minor variations in eccentricity, inclination, argument of perigee, and longitude of the ascending node for 105 revolutions and more. Orbits near the unstable equilibria at 94.56° and 85.44° inclination show very long periodic librations and oscillations between retrogade and prograde motion.Retired from IBM Vienna Software Development Laboratory. 相似文献
389.
以四川西部高原地质环境脆弱为据,提出了“南水北调”西线工程应引以重视的地质环境问题,并以科学发展观提出了对策。 相似文献
390.
Zhang?MeiliangEmail author Yuan?Daoxian Lin?Yushi Cheng?Hai Qin?Jiaming Zhang?Huiling 《中国科学D辑(英文版)》2004,47(1):1-12
A high-resolution climate record from 163.00 kaBP to 113.80 kaBP has been obtained through TIMS-U series dating and carbon
and oxygen isotope analysis of the three large stalagmites from two caves in the south of Guizhou Province, China. The record
of the oxygen isotopes from the stalagmites reveals that the undulation characteristics between the cooling event of the glacial
period and the warming event of the interglacial period in the research area can compare well to those of ice cores, lake
sediments, loess and deep sea sediments on the scale of ten-thousand years or millennium time scale. The climate undulation
provided by the record of the stalagmites has a coherence with the global changes and a tele-connection to the paleoclimate
changes in the north polar region. Our results suggest that the direct dynamics of paleo-monsoon circulation changes reflected
in the record of the stalagmites might be caused by changes of the global ice volume, and in turn related to various factors,
including the solar radiation strength at the mid-latitudes in the Northern Hemisphere, the southern extension of the ice-rafted
event in the North Atlantic, and changes of the equatorial Pacific sea surface temperature at the low-latitudes. Using °18O values, we have calculated the temperatures and the results show that the temperature difference between the penultimate
glacial period (with an average temperature of 8.1°C, and a minimum temperature range from 0.65°C to-1.43°C at stage 6) and
the last interglacial period (with an average temperature of 18.24°C at sub-stage 5e) was about 10°C. This temperature difference
from the record of the stalagmites corresponds in general to the record temperature variation (about 10°C) of measured ice
cores. The climate records from the three stalagmites in the two caves have shown that the circulation strength of the Asian
summer monsoon and the winter monsoon in the penultimate glacial period and the last inter-glacial period had a clear change.
With the TIMS-U series method, termination II of the penultimate glacial period has been precisely dated at an age of (129.28±
1.10) kaBP for the three stalagmites in the south of Guizhou Province, China. This borderline age represents the beginning
of the last interglacial period or the boundary between the Middle Pleistocene and the Late Pleistocene, and corresponds to
the beginning age of the last interglacial period shown by the ice cores and in the SPECMAP curve of the marine oxygen isotopes.
The chronology determination of termination II is not only of stratigraphic and chronological significance, but also lays
an important foundation for discussing the short time scales of climate oscillation and rapidly changing events of paleoclimate
in the circulation region of the East Asian monsoon. 相似文献