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201.
根据IGY/IGC期间全球地磁台网以及中国地磁台站的资料,计算出每-UT小时的Sq外源和内源电流体系.对Sq电流体系UT变化和经度效应的分析研究表明,Sq外源电流体系的空间图案没有显著的UT变化,电流涡焦点的地理纬度与磁赤道有密切关系,其变化范围,北半球为25°-35°N,南半球为30°-42.5°S.外源电流总强度的平均值为229kA(北半球)和173kA(南半球),其变化范围为±50kA(北半球)和±40kA(南半球).Sq内源电流体系的图案和强度有显著的UT变化,电流体系焦点纬度有类似于外源电流系的变化.在大西洋、印度洋、北太平洋地区,内源电流体系的总强度明显小于大陆地区的内源电流强度,表明这些大洋地区上地幔电导率低于大陆地区. 相似文献
202.
203.
我国太平洋深海沉积研究综述 总被引:1,自引:0,他引:1
总结了我国对太平洋深海沉积物组成、分布、形成及深海沉积中宇宙尘、海洋沉积通量、铁锰结核的研究成果,指出了在全球变化研究中太平洋深海沉积的研究课题。 相似文献
204.
Radon-222 activity levels have been measured at deck level in regions of the Arabian Sea, Indian Ocean, and Bay of Bengal during the summer monsoon periods of 1973, 1977, and 1979, as part of the Monex programme. The aim of the measurements was to find the source regions of the monsoon air and the variations in its composition under different synoptic conditions. The radon data confirm that the monsoon air is predominantly of southern-hemisphere origin, with a small continental component. The continental component, as indicated by radon values, increases at higher latitudes and seems to vary with different circulation patterns in the synoptic scale. The use of radon as a tracer in monsoon studies is thus demonstrated. 相似文献
205.
206.
Hydrodynamical Modeling Of Oceanic Vortices 总被引:1,自引:0,他引:1
Xavier Carton 《Surveys in Geophysics》2001,22(3):179-263
Mesoscale coherent vortices are numerous in the ocean.Though they possess various structures in temperature and salinity,they are all long-lived, fairly intense and mostly circular. Thephysical variable which best describes the rotation and the density anomaly associated with coherent vortices is potential vorticity. It is diagnostically related to velocity and pressure, when the vortex is stationary. Stationary vortices can be monopolar (circular or elliptical) or multipolar; their stability analysis shows thattransitions between the various stationary shapes are possible when they become unstable. But stable vortices can also undergo unsteady evolutions when perturbed by environmental effects, likelarge-scale shear or strain fields, -effect or topography. Changes in vortex shapes can also result from vortex interactions. such as the pairing, merger or vertical alignment of two vortices, which depend on their relative polarities and depths. Such interactions transfer energy and enstrophy between scales, and are essential in two-dimensional and in geostrophic turbulence. Finally, in relation with the observations, we describe a few mechanisms of vortex generation. 相似文献
207.
208.
In a recent paper, Nof et al. (J Paleolimnol 35:417–439, 2006) suggest a physical mechanism which could account for the formation
of ice on Lake Kinneret (Sea of Galilee) in northern Israel. Based on the sea surface temperature record of sediment cores
from the Mediterranean Sea the authors argue that centennial-scale cold events had the potential to trigger local ‘springs
ice’ formation on the lake in the past. Here, we demonstrate that a closer inspection of the paleoceanographic record in combination
with correlation and regression analyses of meteorological data provides no evidence for such cold events in the lake region
during the last 10,000 years. Thus, the formation of ‘springs ice’ on Lake Kinneret was unlikely at least since the beginning
of the Neolithic. 相似文献
209.
Timing of the intermediate-basic igneous rocks developed in the area of Kuhai-A'nyêmaqên along the southern east Kunlun tectonic belt is a controversial issue. This paper presents new zircon SHRIMP U-Pb dating data for igneous zircons from the Kuhai gabbro and the Dur'ngoi diorite in the Kuhai-A'nyemaqen tectonic belt, which are 555±9 Ma and 493±6 Ma, respectively. The trace element geochemical features of the Kuhai gabbro and the Dur'ngoi diorite are similar to those of ocean island basalts (OIB) and island arc basalts (IAB), respectively. Thus, the Kuhai gabbro with the age of 555±9 Ma and OIB geochemical features is similar to the Yushigou oceanic ophiolite in the North Qilian orogen, whereas the Dur'ngoi diorite with the age of 493±6 Ma and IAB geochemical features is similar to the island arc volcanic rocks developed in the north Qaidam. The Late Neoproterozoic to Early Ordovician ophiolite complex in the area of Kuhai-A'nyêmaqên suggests that the southern margin of the "Qilian-Qaidam-Kunlun" archipelagic ocean in this period was located in the southern east Kunlun tectonic belt. Therefore, the southern east Kunlun tectonic belt in the early Paleozoic is not comparable to the Mianlüe tectonic belt in the Qinling orogenic belt. 相似文献
210.
海岸海洋潮流模拟可视化与虚拟现实建模 总被引:6,自引:0,他引:6
潮流数值模拟的科学可视化与虚拟现实是海岸海洋科学研究重要的现代技术手段之一。首先从地理信息系统的角度对潮流数值模拟系统的数据模型进行了论述,提出了适合水文数值模拟的对象模型方法;其次探讨了空间流场的可视化技术,阐述了虚拟现实在潮流数值模拟中的作用;最后设计并实现了一个海岸海洋潮流模拟虚拟现实的原型软件系统VRO-cean,并在南黄海辐射沙洲等的潮流数值模拟试验中进行了实际对比检验。 相似文献