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921.
1980~1994年台湾海峡两岸的地热涡与降水季度预报初探   总被引:4,自引:0,他引:4  
利用1980~1994年大陆3.2m深度和台湾3.0m深度的地温资料,分析了15a来的逐季地气图,统计了台湾海峡两岸的地热涡活动,发现平均每季有1个地热涡活动,其水平尺度比大陆内部的地热涡要小,生命史也要短,进入台湾地区的地热涡绝大多数是从西方和北方进入,其移动速度比大陆内部的要快得多。90%以上的地热涡在同期有多雨区与其对应,热涡中心与多雨中心相距在100km以内者占68%。最后给出了一个季度降水的定性预测方案,其步骤为:预报地热涡的中心位置、强度和水平尺度;推算降水正距平区的水平尺度、中心位置和强度;根据本区发生的地震等情况进行预报订正。  相似文献   
922.
河西内陆河春季流量变化特征的分析和预测   总被引:3,自引:0,他引:3  
利用昌马、莺落峡、九条岭3个水文站四十余年的月平均流量资料,分析河西地区3条主要内陆河春季流量的长期变化特征,并用均生函数模型对流量进行了预报,为河西地区水资源的研究和利用提供参考依据  相似文献   
923.
本文对近年来我国西部地区发生的某些强震及中强震(MS>5.0)的波速比异常作了一些初步探讨.文中给出并讨论了这些地震的波速比异常的一些共同特征,即随时间变化的曲线形态、异常特征量(异常持续时间与异常幅度)和异常的统计分布特征.此外还讨论了波速比异常的特性与地震序列类型、震源深度及震源机制的关系,探索了波速比异常与波速异常间的关系.最后还指出了地震活动性与波速比异常的某种对应关系,并作了简要的讨论.  相似文献   
924.
本文介绍了根据近地震直达波到时资料确定震前波速异常区(简称孕震区)的方法,并给出了我国西部地区某些较大地震前波速异常区(孕震区)的初步测定结果。探索并讨论了孕震区的一些基本特性,即孕震区的形状、大小,孕震区的定向,主震在孕震区内所处的部位,孕震区内部波速异常状态的分布与发展等。最后还导出了孕震区线度与震源区尺度间的关系式,并作了简单的讨论。  相似文献   
925.
我们在文[1]里对磁弧剪切作了数值解,得到了剪切速度ω和磁场B_z的分析解,但对二维速度(u,v)的振幅占δ′/ζ仅有只依赖于时间的近似解。本文在密度为常数条件下得到了磁弧剪切在线性演化阶段的较精确的解析解,比较了密度为常数和密度重力分层两种情形下的数值解,证实当β(=气压/磁压)很小(量级为10~(-2))时两者差别不大,因此本文结果近似可用于密度不为常数的实际太阳大气中的磁弧剪切动力学过程。解析解的主要结果是导出振幅δ′/ζ的高度依赖关系:随着时间增加,振幅δ′/ζ随高度下降越来越慢。这导致磁弧顶越升越高而脚根基本上不朝外移动,这样闭合的磁弧将有可能逐渐变为开场。  相似文献   
926.
A model for contact binary systems is presented, which incorporates the following special features: a) The energy exchange between the components is based on the understand-ing that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b) A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point. c) The effects of spin, orbital rota-tion and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered. d) The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M and one 5M star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.  相似文献   
927.
We reported recently some rapid changes of sunspot structure in white-light(WL) associated with major flares.We extend the study to smaller events and present here results of a statistical study of this phenomenon.In total,we investigate 403 events from 1998 May 9 to 2004 July 17,including 40 X-class,174 M-class,and 189 C-class flares.By monitoring the structure of the flaring active regions using the WL observations from the Transition Region and Coronal Explorer(TRACE),we find that segments in the outer sunspot structure decayed rapidly right after many flares;and that,on the other hand,the central part of sunspots near the flare-associated magnetic neutral line became darkened.These rapid and permanent changes are evidenced in the time profiles of WL mean intensity and are not likely resulted from the flare emissions.Our study further shows that the outer sunspot structure decay as well as the central structure darkening are more likely to be detected in larger solar flares.For X-class flares,over 40% events show distinct sunspot structure change.For M-and C-class flares,this percentage drops to 17% and 10%,respectively.The results of this statistical study support our previously proposed reconnection picture,i.e.,the flare-related magnetic fields evolve from a highly inclined to a more vertical configuration.  相似文献   
928.
Based on Hagget's theory of spatial structure,researches on the nodes and field of tourist origins to Huang-cheng Village in Shanxi Province of China have been explored.Nodal hierarchy structure of tourist origins is analyzed with cluster analysis and the gravity model.And field of tourist origins is analyzed with attraction radius index(R)and geography concentration index(G).In the field analysis,R and G of Huangcheng Village are compared with Xidi Village that is a world heritage located in Huangshan City of Anhui Province in China.According to comparison of loca-tions of two areas,influential factors for field area of Huangcheng Village are identified.It is concluded that:1)cluster analysis and gravity model can be complementary methods to each other for nodal hierarchy structure analysis of tour-ist origins;and 2)as far as location is concerned,the weak intensity effect of tourism resources in the tourist region is a major cause for explaining why tourist origins to Huangcheng Village are mainly its neighboring areas.Moreover,it is suggested that the regional effect of tourist resources should be regarded as a component of destination attractiveness when applying gravity model.  相似文献   
929.
1INTRODUCTIONSoil is the basis of human's living. Soil moisture plays asignificant role in studying the matter and energy ex-changes in global hydrology sphere. The evaporation ofsoil moisture has an influence on the water vapor cycle.Meanwhile soil moisture is also one of the firsthandmeasurable parameters in crop yield estimation and wa-ter resources management (JACKSON et al., 1993). Theinfluence of the interaction of land and atmosphere onsoil moisture can bring about anomalous cli…  相似文献   
930.
The progress of the studies on the orientation of galaxies in the Local Supercluster (LSC) is reviewed and a summary of recent results is given. Following a brief introduction of the LSC, we describe the results of early studies based on two-dimensional analysis, which were mostly not conclusive. We describe next the three-dimensional analysis, which is used widely today. Difficulties and systematic effects are explained and the importance of selection effects is described. Then, results based on the new method and modern databases are given, which are summarized as follows. When the LSC is seen as a whole, galaxy planes tend to align perpendicular to the LSC plane with lenticulars showing the most pronounced tendency. Projections onto the LSC plane of the spin vectors of Virgo cluster member galaxies, and to some extent, those of the total LSC galaxies, tend to point to the Virgo cluster center. This tendency is more pronounced for lenticulars than for spirals. It is suggested that ‘field’ galaxies, i.e., those which do not belong to groups with more than three members, may be better objects than other galaxies to probe the information at the early epoch of the LSC formation through the analysis of galaxy orientations. Field lenticulars show a pronounced anisotropic distribution of spin vectors in the sense that they lay their spin vectors parallel to the LSC plane while field spirals show an isotropic spin-vector distribution.  相似文献   
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