大同—怀安麻粒岩地体的伸展抬升

大同－怀安地区ＴＴＧ片麻岩和孔兹岩系早期具有互不相同的，但双彼此相关的构造和演压历史。它们之间的低角度高应变带以正韧性剪切和非共轴变形为特征，体出了构造接触的性质。构造和岩石学数据表明，该地体至少在２．５Ｇａ和１．８Ｇａ前后分别受到两个麻粒岩相变质事件的影响，其主要的构造是在Ｍ１事件中形成的。     

鄂东一次下击暴流天气的中尺度分析

利用自动气象站观测网资料,计算了逐分钟地面散度场,并将散度场等与多普勒天气雷达资料叠加形成综合分析场,对2007年7月27日鄂东地区雷雨大风天气过程进行了中尺度分析。结果表明:地形辐合线对中尺度对流系统(MCS)触发和加强起到重要作用。MCS发生发展期间,多普勒天气雷达上相继有两个弓状回波形成。第一个弓状回波在速度图上因弓状回波移动方向与雷达波束有较大夹角后部入流急流特征不明显,但强度图上有弱回波通道特征;第二个弓状回波沿雷达径向移动,后部入流急流特征明显。武汉地区灾害性雷雨大风是一个强盛的多单体风暴所产生的系列下击暴流造成的,它位于第二弓状回波向前突出的位置。系列下击暴流发生期间,地面附近强辐散峰值与多单体风暴强回波高度显著下降的时间和位置基本一致。除弓状回波特征、后部入流急流、中层速度辐合及回波重心高度下降等特征外,弱回波通道、风暴相对速度图上沿雷达波束方向的正负速度对等也是下击暴流发生的典型特征。     

春播期亚欧环流形势的客观分型及其在物理-统计预报中的应用

本文对1972—1978年七年春播期(3月27日—5月10日)500mb亚欧环流形势,应用变K-均值聚类法进行客观分型,共得九型。对它们和春播期四种主要中期天气过程——连阴雨和低温连阴雨、过程性天气、连晴,用对应分析方法数量化。以环流形势与同期的北半球500mb波谱分析中选出的物理量作为因子,对天气过程类型作出了逐步回归和AID聚类的统计推断。 对1979、80年春播期作了预报检验,效果尚好。     

地震行业地面骨干网与应急卫星通信网互联路由设计方案的探讨

本文介绍了地震行业地面骨干网与应急卫星通信网的运行现状及互联存在的路由问题,讨论了实现两网互联的路由设计目标和策略,根据OSPF协议与BGP协议的特点和适用范围,提出了统一互联的接入方法,以及联合使用OSPF和BGP协议解决两网互联路由问题的具体方案,经网络仿真平台测试证明,该方案切实可行,效果良好。     

居室氡的影响因素及分布特点

氡是天然放射性系列铀系中唯一的气态元素,它对人体健康的影响尤其是氡与肺癌的关系已引起人们的高度重视,已成为环境保护研究的一个重要对象.本文就地壳中放射性元素的分布规律及氡的迁移进行介绍,并着重讨论了居室氡的影响因素,以期利于今后氡危害防治工作的进行.     

湘西自治州北部铅锌矿找矿标志及找矿远景区

湘西自治州北部铅锌矿带,处于桑植复向斜西南段,长100km以上,宽50km左右,矿带内铅锌矿点广布,受地层、构造、岩性的控制。上寒武统耗子沱群至下奥陶统大湾组共有7个含矿层位,北东向背斜倾伏端及北东向断裂、层间裂隙以及次级北西向横跨背斜是矿床控矿构造,有矿体赋存的含矿层有明显的硅化作用,且硅化体中Pb,Zn,Cu明显富集,分别为地层的66、32、8倍,Sr/Ba比值为0.60,无矿存在的硅化体则Pb,Zn,Cu含量接近地层或稍高于地层,Sr/Ba比值高达1.15。在砂子坡背斜南翼、红岩溪背斜北东端和南西倾伏端、盐井背斜,下奥陶统红花园组顶部含矿层内为找矿远景区。     

Climatic change and Chinese population growth dynamics over the last millennium

The climate–population relationship has long been conceived. Although the topic has been repeatedly investigated, most of the related works are Eurocentric or qualitative. Consequently, the relationship between climate and population remains ambiguous. In this study, fine-grained temperature reconstructions and historical population data sets have been employed to statistically test a hypothesized relationship between temperature change and population growth (i.e., cooling associated with below average population growth) in China over the past millennium. The important results were: (1) Long-term temperature change significantly determined the population growth dynamics of China. However, spatial variation existed, whilst population growth in Central China was shown to be responsive to both long- and short-term temperature changes; in marginal areas, population growth was only sensitive to short-term temperature fluctuations. (2) Temporally, the temperature–population relationship was obscured in some periods, which was attributable to the factors of drought and social buffers. In summary, a temperature–population relationship was mediated by geographic factors, the aridity threshold, and social factors. Given the upcoming threat posed by climate change to human societies, this study seeks to improve our knowledge and understanding of the climate–society relationship.     

A Large-Eddy Simulation and Lagrangian Stochastic Study of Heavy Particle Dispersion in the Convective Boundary Layer

Large-eddy simulation and Lagrangian stochastic dispersion models were used to study heavy particle dispersion in the convective boundary layer (CBL). The effects of various geostrophic winds, particle diameters, and subgrid-scale (SGS) turbulence were investigated. Results showed an obvious depression in the vertical dispersion of heavy particles in the CBL and major vertical stratification in the distribution of particle concentrations, relative to the passive dispersion. Stronger geostrophic winds tended to increase the dispersion of heavy particles in the lower CBL. The SGS turbulence, particularly near the surface, markedly influenced the dispersion of heavy particles in the CBL. For reference, simulations using passive particles were also conducted; these simulation results agreed well with results from previous convective tank experiments and numerical simulations.     

Changes in temperature and precipitation extremes in the CMIP5 ensemble

Twenty-year temperature and precipitation extremes and their projected future changes are evaluated in an ensemble of climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5), updating a similar study based on the CMIP3 ensemble. The projected changes are documented for three radiative forcing scenarios. The performance of the CMIP5 models in simulating 20-year temperature and precipitation extremes is comparable to that of the CMIP3 ensemble. The models simulate late 20th century warm extremes reasonably well, compared to estimates from reanalyses. The model discrepancies in simulating cold extremes are generally larger than those for warm extremes. Simulated late 20th century precipitation extremes are plausible in the extratropics but uncertainty in extreme precipitation in the tropics and subtropics remains very large, both in the models and the observationally-constrained datasets. Consistent with CMIP3 results, CMIP5 cold extremes generally warm faster than warm extremes, mainly in regions where snow and sea-ice retreat with global warming. There are tropical and subtropical regions where warming rates of warm extremes exceed those of cold extremes. Relative changes in the intensity of precipitation extremes generally exceed relative changes in annual mean precipitation. The corresponding waiting times for late 20th century extreme precipitation events are reduced almost everywhere, except for a few subtropical regions. The CMIP5 planetary sensitivity in extreme precipitation is about 6 %/°C, with generally lower values over extratropical land.     

Land surface temperature shaped by urban fractions in megacity region

The influence of spatial scales on surface fluxes is an interesting but not fully investigated question. This paper presents an analysis on the influence of spatial scales on surface fluxes in the north Tibetan Plateau based on eddy covariance (EC) and large aperture scintillometer (LAS) data at site Nagqu/BJ, combined with the land surface temperature (LST) and normalized difference vegetation index (NDVI) of moderate-resolution imaging spectroradiometer (MODIS). The analysis shows that sensible heat fluxes calculated with LAS data (H_LAS) agree reasonably well with sensible heat fluxes calculated with EC data (H_EC) in the rain and dry seasons. The difference in their footprints due to the wind direction is an important reason for the differences in H_EC and H_LAS. The H_LAS are statistically more consistent with H_EC when their footprints overlap than when their footprints do not. A detailed analysis on H_EC and H_LAS changes with net radiation and wind direction in rain and dry season indicates that the spatial heterogeneity in net radiation created by clouds contributes greatly to the differences in H_EC and H_LAS in short-term variations. A significant relationship between the difference in footprint-weighted averages of LST and difference in H_EC and H_LAS suggests that the spatial heterogeneity in LST at two spatial scales is a reason for the differences in H_EC and H_LAS and that LST has a positive correlation with the differences in H_EC and H_LAS. A significant relationship between the footprint-weighted averages of NDVI and the ratio of sensible heat fluxes at two spatial scales to net radiation (H/Rn) in the rain season supports the analysis that the spatial heterogeneity in canopy at two spatial scales is another reason for differences in H_EC and H_LAS and that canopy has a negative correlation with (H/Rn). An analysis on the influence of the difference in aerodynamic roughness lengths at two spatial scales on sensible heat fluxes shows that the influence is greater in the dry season and smaller in the rain season because the ratio of z_{0m_LAS} to z_{0m_EC} is big in the dry season and is close to 1.0 in the rain season. This study on spatial scales on surface fluxes in the Tibetan Plateau will be helpful in analyzing and understanding its influence on climate.