地球内核快速旋转的发现与全球变化的轨道效应   总被引：3，自引：0，他引：3  

杨学祥  陈震  刘淑琴  宋秀环  陈殿友 《地学前缘》1997,(Z1)

科里奥利效应是产生内核快速旋转的主要原因。科氏力使上升物质向西漂移，下降物质向东漂移；造成地球外层自转减速，地球内层自转加速。所以，自旋体中的垂直运动可以产生大规模的水平运动——圈层差异旋转。地震波测量结果表明，内核旋转速度每年比地壳地幔快１°。对于一个内核差异旋转的地球，太阳辐射不仅形成地磁场的内外磁尾和地壳与内核的反向振动，而且影响核幔角动量交换和电磁耦合，从而控制了地球内能的释放，形成天文周期与地质旋回的一一对应关系。地球轨道和太阳轨道的全球变化响应，为太阳辐射量变化控制地球内能释放提供了证据  相似文献   

EXPERIMENTAL STUDY ON EFFECTS OF HUMIDITY AND CHEMICAL COMPOSITION UPON IMAGINARY PART OF REFRACTIVE INDEX OF AEROSOL PARTICLES^*          下载免费PDF全文

LI Zihu  DONG Zhen  YANG Jun  HUANG Shihong 《Acta Meteorologica Sinica》2004,18(4):517-526

Experimental study is made of the relationship between the imaginary part of refractive index (IRI) of atmospheric aerosol particles and relative humidity,and between IRI and chemical element through the assay of chemical constituents of the particles.Evidence suggests that atmospheric humidity and aerosols' chemical ingredients have great effects on the IRI's and they should thus be considered in the research of the radiation properties of the particles in the atmosphere.  相似文献   

Comparison of Aircraft and Ground-Based FluxMeasurements during OASIS95     

P. R. Isaac  J. Mcaneney  R. Leuning  J. M. Hacker 《Boundary-Layer Meteorology》2004,110(1):39-67

Aircraft and ground-based measurements made during the1995 Australian OASIS field campaign are compared. The aircraft data were recorded during low-level flightsat 6 m above ground level and grid flights at altitudes of between 15 and 65 m, allin unstable atmospheric conditions. The low-level flights revealed an inadequate temperaturesensor response time, a correction for which was determined from subsequent work ina wind tunnel. Aircraft and ground-based measurements of mean wind speed, wind directionand air temperature agree to within 0.2 m s^-1, 4° and 0.9 °C respectively.Comparisons between aircraft and ground-based observations of the standarddeviations of vertical velocity, horizontal wind speed, air temperature and specifichumidity have slopes of 0.96, 0.97, 0.92 and 0.99 respectively but the observed scatter isroughly twice the random error expected due to the averaging length of the aircraft data andthe averaging period of the ground-based data. For the low-level flights, the ground-basedand aircraft measurements of sensible and latent heat flux show mean differences of 27 and-25 W m^-2 respectively, which reduce to 11 and -4 W m^-2 respectivelywhen analysis of aircraft data is limited to areas immediately adjacent to the fluxtowers. For the flights at 15 to 65 m above ground level, the mean differences between theground-based and aircraft measurements of sensible and latent heat flux are -22 and-1 W m^-2 respectively and these change to -1 and -7 W m^-2 respectively oncethe effect of surface heterogeneity is included. Aircraft and ground-based measurementsof net radiation agree to within 6% at one ground-based site but differ by 20% at a second.Aircraft measurements of friction velocity at 6 m above the ground agree well withground-based data, but those from flights between 15 and 65 m above ground level do not.This is because at these heights the aircraft measurements provide the local shear stress,not the surface shear stress. Overall, the level of agreement allows confidence in the aircraftdata provided due care is taken of instrument response times and differences in thesurfaces sampled by aircraft and ground-based systems.  相似文献   

Radiative Exchange in an Urban Street Canyon   总被引：1，自引：4，他引：1  

Ian N. Harman  Martin J. Best  Stephen E. Belcher 《Boundary-Layer Meteorology》2004,110(2):301-316

The influence of building geometry on the radiation terms ofthe surface energy balance is a principal reason for surfacetemperature differences between rural and urban areas.Methods exist to calculate the radiation balance in an urban area,but their validity across the range of urban geometries andmaterials has not been carefully considered.Here the exchange of diffuse radiation in an urban street canyon isinvestigated using a method incorporating all reflections of radiation.This exact solution is compared to two commonly used approximationsthat retain either no reflections, or just one reflection of radiation.The area-averaged net radiative flux density from the facets of the canyondecreases in magnitude monotonically as the canyon aspect ratio increases.The two approximate solutions possess unphysical differences from thismonotonic decrease for high canyon aspect ratios or low materialemissivities/high material albedos.The errors of the two approximate solutions are small for near blackbodymaterials and small canyon aspect ratios but can be an order ofmagnitude for intermediate material properties and deep street canyons.Urban street canyon models need to consider at least one reflectionof radiation and multiple reflections are desirable for full applicability.  相似文献   

Estimation of Regional Evapotranspiration by Combining Aircraftand Ground-Based Measurements     

P. R. Isaac  R. Leuning  J. M. Hacker  H. A. Cleugh  P. A. Coppin  O. T. Denmead  M. R. Raupach 《Boundary-Layer Meteorology》2004,110(1):69-98

Two methods are examined for combining measurements from instrumented aircraftand towers to estimate regional scale evapotranspiration. Aircraft data provided spatially averaged values of properties of the surface, the evaporative fraction and maximum stomatal conductance. These quantities are less sensitive to meteorological conditions than the turbulent fluxes of heat and water vapour themselves. The methods allowed aircraft data collected over several days to be averaged and thus to reduce the random error associated with the temporal under-sampling inherent in aircraft measurements. Evaporative fraction is estimated directly from the aircraft data, while maximum stomatal conductance is estimated by coupling the Penman–Monteith equation to a simple model relating surface conductance to the incoming shortwave radiation and specific humidity saturation deficit. The spatial averages of evaporative fraction and maximum stomatal conductance can then be used with routine tower data to estimate the regional scale evapotranspiration. Data from aircraft flights and six ground based sites during the OASIS field campaign in south–east New South Wales in 1995 have been used to check the methods. Both the evaporative fraction and the maximum stomatal conductance derived from the aircraft data give information on the spatial variability of the surface energy budget at scales from 10 to 100 km. Daily averaged latent heat fluxes estimated using these methods for the OASIS study region agree with the available observations in quasi-stationary conditions or in weakly non-stationary conditions when the data from several aircraft flights are averaged to reduce the impact of short term imbalances in the surface energy budget.  相似文献   

程海断裂带断层泥中石英碎砾表面SEM特征及断层活动状态的分析   总被引：4，自引：0，他引：4  

俞维贤  王彬  毛燕  杨继武 《中国地震》2004,20(4):347-352

根据断层泥中石英碎砾表面SEM特征的鉴定研究，可将程海断裂中、北段断层泥中石英碎砾表面SEM形貌特征分为6类，这表明该段断裂经历了长期多期次活动，强烈活动时间在中晚更新世；5件样品中均未见破裂类(Io)的石英颗粒，表明程海断裂全新世以来强烈活动的频度相对较低。石英碎砾表面机械作用特征的分类统计研究显示：程海断裂中、北段晚更新世以来，断层所经历的活动方式以粘滑活动为主。  相似文献   

Parameters of Land-Surface Processes for Gobi in North-West China   总被引：1，自引：0，他引：1  

Zhang Qiang  Huang Ronghui 《Boundary-Layer Meteorology》2004,110(3):471-478

Using data from the intensive observation period (May–June 2000) of the NWC-ALIEX (The Field Experiment on Interaction between Land and Atmosphere in Arid Region of North-west China), the characteristics and mechanisms of some key land-surface process over Gobi in a typical arid region of north-west China are analyzed and several parameters of land-surface processes are calculated. The weighted mean of the surface albedo over a typical arid region of the Dunhuang Gobi is calculated using the relative reflection as a weighting factor, and its value is 0.255 ± 0.021. After removing the influence of precipitation, the mean soil heat capacity over a typical arid region of the Dunhuang Gobi is 1.12 × 10⁶ J m^-3 K^-1,which is smaller than that observed in the Heihe (China) River basin Field Experiment (HEIFE). The mean soil heat diffusivity and conductivity are about half of those observed in HEIFE.  相似文献   

Ambiguous Moment Tensors and Radiation Patterns in Anisotropic Media with Applications to the Modeling of Earthquake Mechanisms in W-Bohemia   总被引：3，自引：0，他引：3  

Rössler  D.  Rümpker  G.  Krüger  F. 《Studia Geophysica et Geodaetica》2004,48(1):233-250

Anisotropic material properties are usually neglected during inversions for source parameters of earthquakes. In general anisotropic media, however, moment tensors for pure-shear sources can exhibit significant non-double-couple components. Such effects may be erroneously interpreted as an indication for volumetric changes at the source. Here we investigate effects of anisotropy on seismic moment tensors and radiation patterns for pure-shear and tensile-type sources. Anisotropy can significantly influence the interpretation of the source mechanisms. For example, the orientation of the slip within the fault plane may affect the total seismic moment. Also, moment tensors due to pure-shear and tensile faulting can have similar characteristics depending on the orientation of the elastic tensor. Furthermore, the tensile nature of an earthquake can be obscured by near-source anisotropic properties. As an application, we consider effects of inhomogeneous anisotropic properties on the seismic moment tensor and the radiation patterns of a selected type of micro-earthquakes observed in W-Bohemia. The combined effects of near-source and along-path anisotropy cause characteristic amplitude distortions of the P, S1 and S2 waves. However, the modeling suggests that neither homogeneous nor inhomogeneous anisotropic properties alone can explain the observed large non-double-couple components.The results also indicate that a correct analysis of the source mechanism, in principle, is achievable by application of anisotropic moment tensor inversion.  相似文献   

A Preliminary Analysis of Relations Between Tectonic Deformation of Sedimentary Cover and Basement in Kuqa Depression     

Liu Jie 《中国地震研究》2004,18(4):406-416

Study of seismic activity in the Kuqa area enables us to infer some possible active faults in basement from the epicentral distribution on different profiles. The relations between active faults in the basement and surface structures are analyzed and the difference between sedimentary cover and basement in their deformation characteristics and the genesis are discussed. The following conclusions have been drawn : ( 1 ) the epicentral distribution indicates that, the east Qiulitag and south and north Qiulitag deep faults in the basement correspond to the east and west Qiulitag anticlines, respectively. Moreover, deep faults also exist beneath the Yiqiklik and Yaken anticlines. It indicates that the formation of surface structures is controlled by deep structures; (2) A NE-trending strike-slip fault develops along the line from the western termination of Yiqiklik structure to Dongqiu Well 5 and a NW-trending active fault on the western side of Baicbeng. The two active faults across the tectonic strike are the main causes for tectonic segmentation of the Kuqa depression and possibly the cause for the middle segment (Kuqa-Baicheng) of the depression to be more shortened than both its eastern and western terminations; (3) The difference between the sedimentary cover and basement in their deformation characteristics depends mainly on the different properties of media between them.The lithospheric strength of the basement in the basin is fairly high, which determines the basement deformation to be mainly of brittle fracture seismic activity. While the strength of sedimentary cover is low, where there exist weak thin layers, such as coal and gyps. Under the effect of strong tectonic compression, the sedimentary rocks may undergo strong viscous or plastic flow deformation; meanwhile, an aseismic detachment may take place along the weak layers.  相似文献   

济南、福山太阳辐射的气候学特征分析   总被引：1，自引：0，他引：1  

房岩松  盛立芳  邱明燕 《山东气象》2004,24(4):5-8

利用济南、福山地面太阳辐射资料，分析了太阳辐射的气候变化特征。结果表明，60到90年代，济南地面太阳总辐射量、直接辐射量呈显著减少趋势，福山变化趋势不明显；90年代以后，济南地面太阳总辐射呈增多趋势。  相似文献