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431.
利用欧拉定律和ITRF2005的速度场,给出了全球板块运动模型ITRF2005VEL,并计算了全球地壳旋转总角动量之和。采用离散的Tisserand条件对实测的全球台站运动速度进行约束,建立了一个新的基于NNR参考框架的实测的绝对板块运动模型NNR-ITRF2005,并与地学模型NNR-NUVEL1A和ITRF其他序列建立的NNR模型进行了比较和分析。结果表明,从整体上来看,NNR-ITRF2005比较接近于NNR-NU-VEL1A,但个别板块由于测站较少、分布不均或者测站观测时间短对板块的约束不够等原因,使得这些板块的欧拉极与地学模型的偏差较大。 相似文献
432.
433.
Calculation of circulation in the South China Sea during summer of 2000 by the modified inverse method 总被引:3,自引:0,他引:3
YUAN Yaochu LIU Yonggang LIAO Guanghong LOU Ruyun SU Jilan WANG Kangshan 《海洋学报(英文版)》2005,24(1):14-30
On the basis of hydrographic data obtained in August 2000 cruise, the circulation in the South China Sea (SCS) is computed by the modified inverse method in combination with SSH data from TOPEX/ERS-2 analysis. For study of the dynamical mechanism, which causes the pattern of summer circulation in the SCS, the diagnostic model (Yuan et al. 1982. Acta Oceanologica Sinica,4(1):1-11; Yuan and Su. 1992. Numerical Computation of Physical Oceanography.474-542) is used to simulate numerically the summer circulation in the SCS. The following results 相似文献
434.
M. Malinowski A. ela
niewicz M. Grad A. Guterch T. Janik CELEBRATION Working Group 《Tectonophysics》2005,401(1-2):55-77
The CELEBRATION 2000 together with the earlier POLONAISE'97 deep seismic sounding experiments was aimed at the recognition of crustal structure in the border zone between the Precambrian East European Craton (Baltica) and Palaeozoic Europe. The CEL02 profile of the CELEBRATION family is a 400-km long SW–NE transect, running in Poland from the Upper Silesia Block (USB), across the Małopolska Block (MB) and the Trans-European Suture Zone (TESZ) to the East European Craton (EEC). The structure along CEL02 was interpreted using both 2D tomography and forward ray-tracing techniques as well as 2D gravity modelling.The crustal thickness along CEL02 varies from 32–35 km in the USB to 45–47 km beneath the TESZ and the EEC. The USB is a clearly distinctive crustal block with the characteristic high velocity lower crust (7.1–7.2 km/s), interpreted as a fragment of Gondwana. The Kraków–Lubliniec Fault is a terrane boundary produced by soft docking of the USB with the MB. The Małopolska crust fundamentally differs from the USB and has a strong connection with Baltica. It is a transitional, 150- to 200-km wide unit composed of the extended Baltican lower crust and the overlying low velocity (5.15–5.9 km/s) Neoproterozoic metasediments in the up to 18-km thick upper crust. The Łysogóry Unit has its crustal structure identical with that of Małopolska, thus it is connected with Baltica and cannot be interpreted as a Gondwana-derived terrane. Higher velocity and density bodies found below the Mazovia–Lublin Graben at a depth of 12 km and at the base of the lower crust, might be a result of mantle-derived mafic intrusions accompanying the extension of Baltica. By the preliminary 2D gravity modelling, we have reconfirmed the need for considering the increased TESZ mantle density in comparison to the EEC and USB mantle. 相似文献
435.
2000国家大地坐标系(CGCS2000)成果的获取技术涉及国际地球参考框架(ITRF)、参考历元、卫星星历及站点速度场等归算问题.介绍了不同参考框架的转换模型和参数,讨论了获取CGCS2000成果的数据处理方法,利用实测观测数据分析了IERS发布的不同ITRF参考框架和不同国际机构发布的各种不同类型的星历对基线结果的影响,以及直接平差与采用框架转换方法求得CGCS2000坐标成果的差异.结果表明:IGS发布的星历精度要高于其他机构发布的精密星历;不同参考框架的精密星历对基线长度在4000km以内的基线影响小于1.3mm,一般在控制网基线解算时可不考虑卫星星历参考框架的影响;在获取CGCS2000成果时,可不考虑星历的类型、参考框架及历元问题;非ITRF97、2000.0成果可采用框架转换公式及转换参数进行成果归算得到CGCS2000成果. 相似文献
436.
基于中国气象局提供的气象站点月值资料,NOAA、CMAP降水格点月值资料,NDVI卫星资料及再分析资料,利用统计方法分析了1961-2014年青藏高原感热与中国东部季风雨带关键区夏季降水的年代际变化,并根据热动力平衡方程结合CESM模式试验解释了21世纪初高原感热异常对关键区夏季降水的影响机理.结果表明:21世纪初,黄淮、江淮地区降水增加,而长江以南地区降水减少.同时,高原感热也发生年代际增强,当春季感热增强后,大气热能上传导致夏季高原近地面产生气旋性环流异常,大气辐合;高层产生反气旋性环流异常,大气辐散.黄淮、江淮地区在对流层中低层受异常偏南风控制,高层受高原上空的大尺度反气旋环流影响产生异常偏北风.此外,高原感热增强通过影响黄淮、江淮地区产生暖平流输送和非绝热加热正异常,该区域产生异常的上升运动,降水量增加.长江以南地区在对流层中低层存在一个异常的反气性环流,有来自海洋的冷平流输送,同时大气非绝热加热在该地区为负异常,产生异常的下沉运动,降水量减少.模式敏感性试验的结果证实了当高原感热发生年代际增强,黄淮、江淮地区水平温度平流及非绝热加热为正异常,而在华南地区为负异常,从而导致黄淮、江淮地区大气上升运动增强,降水增加;而华南地区下沉运动增强,降水减少.
相似文献437.
438.
The error of closure in the 2000 census, or the difference between estimated and enumerated populations, poses special problems for public agencies that rely on census data. Nationally and at the state level, populations were only slightly underestimated, but underestimations were high in rapidly growing counties in the South and intermontaine West, as well as in New York City. Race‐specific estimates proved far less reliable, with severe overestimates and underestimates of all racial groups in various counties nationwide. We offer explanations for the estimation error and discuss its impact on cancer rates and trends and its implications for cancer surveillance research. 相似文献
439.
The USGS has developed several mathematical models to forecast reserve growth of fields both in the United States (U.S.) and
the world. The models are based on historical reserve growth patterns of fields in the U.S. The patterns of past reserve growth
are extrapolated to forecast future reserve growth. Changes of individual field sizes through time are extremely variable,
therefore, the reserve growth models take on a statistical approach whereby volumetric changes for populations of fields are
used in the models. Field age serves as a measure of the field-development effort that is applied to promote reserve growth.
At the time of the USGS World Petroleum Assessment 2000, a reserve growth model for discovered fields of the world was not
available. Reserve growth forecasts, therefore, were made based on a model of historical reserve growth of fields of the U.S.
To test the feasibility of such an application, reserve growth forecasts were made of 186 giant oil fields of the world (excluding
the U.S. and Canada). In addition, forecasts were made for these giant oil fields subdivided into those located in and outside
of Organization of Petroleum Exporting Countries (OPEC). The model provided a reserve-growth forecast that closely matched
the actual reserve growth that occurred from 1981 through 1996 for the 186 fields as a whole, as well as for both OPEC and
non-OPEC subdivisions, despite the differences in reserves definition among the fields of the U.S. and the rest of the world. 相似文献
440.
The contribution of the International VLBI Service for Geodesy and Astrometry (IVS) to the ITRF2005 (International Terrestrial
Reference Frame 2005) has been computed by the IVS Analysis Coordinator’s office at the Geodetic Institute of the University
of Bonn, Germany. For this purpose the IVS Analysis Centres (ACs) provided datum-free normal equation matrices in Solution
INdependent EXchange (SINEX) format for each 24 h observing session to be combined on a session-by-session basis by a stacking
procedure. In this process, common sets of parameters, transformed to identical reference epochs and a prioris, and especially representative relative weights have been taken into account for each session. In order to assess the quality
of the combined IVS files, Earth orientation parameters (EOPs) and scaling factors have been derived from the combined normal
equation matrices. The agreement of the EOPs of the combined normal equation matrices with those of the individual ACs in
terms of weighted root mean square (WRMS) is in the range of 50–60 μas for the two polar motion components and about 3 μs
for UT1−UTC. External comparisons with International GNSS Serive (IGS) polar motion components is at the level of 130–170 μas
and 21 μs/day for length of day (LOD). The scale of the terrestrial reference frame realized through the IVS SINEX files agrees
with ITRF2000 at the level of 0.2 ppb. 相似文献