湖北2015年冬季PM2.5重污染过程的气象输送条件及日变化特征分析

PM_2.5污染仍然是湖北省冬季大气污染的首要污染类型,且具有明显区域传输特征,重污染过程的空气污染气象条件有别于华北地区,值得关注。采用WRF/Chem不同排放情景下的模拟结果,并结合观测分析,研究了2015年12月—2016年1月湖北省PM_2.5重污染过程的气象输送条件及日变化特征,从大尺度输送条件和局地边界层动力作用分析了外来污染物水平传输、悬浮聚集和向下传输的过程,并解释了该地区观测到的午后PM_2.5浓度特殊峰值的气象成因。结果表明,湖北重污染爆发以区域传输为主,地面观测PM_2.5极值对应10 m风速可达8—10 m/s,边界层0—1 km为较强偏北风输送,污染传输通量极值位于400 m高度附近,为重要传输通道,低空无明显逆温,重污染过程具有“非静稳”边界层气象特征。重污染形成的大尺度输送条件为,长江中下游及北部地区偏北风异常偏强,南部地区风速减缓,使污染物在中游平原堆积,鄂北边界风速越大,越有利污染输送增长。传输性污染主要来自偏北和东北方向的污染源输送,潜在源区贡献主要为途经偏北通道上的豫中、南阳盆地和关中地区,以及途经东北通道上的鲁、皖、苏等部分地区。PM_2.5浓度日变化双峰结构的天气成因不同,21—24时（北京时）峰值为静稳性污染,11—14时峰值为传输性污染。污染输送受大气边界层高度影响,日出前大气边界层高度较低,层结稳定并伴有上升运行,使得低空外来输送悬浮聚集在400 m高度附近;日出后随大气边界层高度升高,静稳层结被破坏,在干沉降作用下高浓度PM_2.5开始向下传输,并在午后地面形成峰值。      

Typology of Natural Hazards and Assessment of Associated Risks in the Mount Bambouto Caldera(Cameroon Line,West Cameroon)

Mount Bambouto is a polygenic stratovolcano of the Cameroon Volcanic Line,built between 21 Ma and 4.5 Ma.It is situated approximately 200 km NE of Mount Cameroon,between 09°55′and 10°15′longitude east and,05°25′and 05°50′latitude north.The volcano covers an area of 500 km~2 and culminates at 2740 m at Meletan dome and bears a collapsed caldera at the summit (13×8 km).Mount Bambouto is characterized by several natural hazards of different origins: meteorological,such as landslides and rock falls;anthropog...     

层状云播云线源非均匀、非定常输送扩散数值模拟

大多数层状云播云线源输送扩散模式常采用一些不合理的假设，使得输送扩散过程中起重要作用的一些物理过程被忽略。烟团轨迹模式能够处理源参数和气象要素的时空变化，适用于各种尺度和各类源的输送扩散模拟。因此，本文建立了一个模拟层状云播云线源输送扩散的三维时变烟团轨迹模式，并考虑了地形，垂直风切变作用，播云参数的时空变化和线源的湿清除效应。增雨作业实例我的数值模拟研究结果表明：模拟的播云线源输送扩散特征与输送扩散的基本理论和一般规律相吻合，并且再现了非垂直（与风向上）多条播云线源非均匀非定常的输送扩散特点。浓度等值线水平，垂直分布均不规则，比均匀定常点源更为复杂，整体不满足高斯浓度分布，表明在这种情况下均匀定常模式已不适用。另外，模式能够精确地模拟出播云线间的精细结构。     

辐射井在北京地铁五号线降水工程中的应用

北京地铁五号线纵贯城区南北，传统降水施工受到限制，局部地段根本无法实施。采用辐射井降水工艺，既解决了降水问题，取得了良好效果，又为辐射井在地下工程降水应用开辟了新途径。着重介绍了辐射井施工技术原理、技术要求、遇到的困难及解决对策和建议。     

扫描地形图中方里网的自动去除

提出了一种去除方里网的自动算法 ,实验证明 ,该方法不但有效地去除了扫描地形图中的全部方里网线 ,而且还很好地保持了其它要素的完整性。     

Al3+掺杂锂皂石的合成及其性能研究

采用水热法合成锂皂石,以LiCl-MgCl2-Na2SiO3-H2O为主要反应体系,加入NaOH调节反应体系的pH值,通过加入Al2(SO4)3.18H2O而引入Al3+进行掺杂改性,合成了系列锂皂石。对所得产物进行XRD检测,探测了产物的结晶化度和结构组成。通过分光光度计和流变仪测定了产物的透光性及粘度性能,结果发现反应体系pH值的变化可引起锂皂石产品水分散体系的透明度;控制一定的Al3+加入量,可得到具有较高粘度的锂皂石产品。     

FeO*-Al2O3-TiO2-Rich Rocks of the Tertiary Bana Igneous Complex, West Cameroon

FeO*‐Al₂O₃‐TiO₂‐rich rocks are found associated with transitional tholeiitic lava flows in the Tertiary Bana plutono‐volcanic complex in the continental sector of the Cameroon Line. These peculiar rocks consist principally of iron‐titanium oxides, aluminosilicates and phosphates, and occur as layers 1–3 m thick occupying the upper part of lava flows on the southwest (site 1) and northwest (site 2) sites of the complex. Mineral constituents of the rocks include magnetite, ilmenite, hematite, rutile, corundum, andalusite, sillimanite, cordierite, quartz, plagioclase, alkali feldspar, apatite, Fe‐Mn phosphate, Al phosphate, micas and fine mixtures of sericite and silica. Texturally and compositionally, the rocks can be subdivided into globular type, banded type, and Al‐rich fine‐gained massive type. The first two types consist of dark globule or band enriched in Fe‐Ti oxides and apatite and lighter colored groundmass or bands enriched in aluminosilicates and quartz, respectively. The occurrence of andalusite and sillimanite and the compositional relations of magnetite and ilmenite in the FeO*‐Al₂O₃‐TiO₂‐rich rocks suggest temperatures of crystallization in a range of 690–830°C at low pressures. The Bana FeO*‐Al₂O₃‐TiO₂‐rich rocks are characterized by low concentrations of SiO₂ (25–54.2 wt%), Na₂O + K₂O (0–1%), CaO (0–2%) and MgO (0–0.5%), and high concentrations of FeO* (total iron as FeO, 20–42%), Al₂O₃ (20–42%), TiO₂ (3–9.2%), and P₂O₅ (0.26–1.30%). TiO₂ is positively correlated with Al₂O₃ and inversely correlated with FeO*. The bulk rock compositions cannot be derived from the associated basaltic magma by crystal fractionation or by partial melting of the mantle or lower crustal materials. In ternary diagrams of (Al₂O₃)?(CaO + Na₂O + K₂O)?(FeO*+ MnO + MgO) and (SiO₂)?(FeO*)?(Al₂O₃), the compositional field of the rocks is close to that of laterite and is distinct from the common volcanic rocks, suggesting that the rocks are derived from lateritic materials by recrystallization when the materials are heated by the basaltic magmas. A hydrothermal origin is discounted because the rocks contain high‐temperature mineral assemblages and lack sulfide minerals. It is proposed that the FeO*‐Al₂O₃‐TiO₂‐rich rocks of the Bana complex were formed by pyrometamorphism of laterite by the heat of basaltic magmas.     

Anisotropic Mean Traveltime Curves: A Method to Estimate Anisotropic Parameters from 2D Transmission Tomographic Data

We present the mathematical deduction and properties of the mean traveltime curves for homogeneous elliptical anisotropic media. These curves generalize their isotropic counterparts which have been introduced in the past as a simple data quality analysis technique at the pre-inversion stage for 2D transmission experiments, allowing the inference of prior velocity models to gain stability at the tomographic inversion. Also, the anisotropy parameters (maximum velocity, anisotropic direction and ratio) are shown to affect the shape of these curves. The degree of asymmetry of the anisotropic mean traveltime curves (displacement of the mean time and standard deviation minima from the middle of the gathering line) is related to the direction of anisotropy which can then be visually estimated. Least squares’ fitting of the anisotropic theoretical models to their experimental counterparts is an effective method to estimate at the pre-inversion stage a macroscopic elliptical anisotropic velocity model, valid at the scale of the experiment, and able to match the experimental mean traveltime distribution. Sensitivity analysis has shown that the mean curve is less prone to errors than the standard deviation curve. Parameter identification from the standard deviation curve becomes unstable for noise levels higher than 5%; data errors produce smearing of the value of the estimated anisotropy ratio and wrong directions of anisotropy biased towards zero degrees. Also, identification from the mean traveltime curve becomes stable when the maximum velocity is well constrained. Finally, this methodology is illustrated with the application to the Grimsel data set. Performing MTC analysis is always recommended since it does not need high numerical requirements, and as shown in the sensibility analysis section, errors in data can be misinterpreted as geological anisotropies. J.L. Fernández Martínez is a visiting professor at UC Berkeley, Department of Civil and Environmental Eng., CA 94720-1710.     

SAR影像在立体测图中的应用

通过对机栽2．5m分辨率SAR影像的布点、平差及单片计算,进一步构建了邻航线间SAR影像的立体模型配对,并通过FeatureStation工作平台的矢量化采集,完成了1：50000比例尺的DLG测图工作。     

省级基础测绘1：10000 DLG成果的质量检查

1∶10 000DLG是省级基础测绘的核心成果。本文论述了DLG成果质量检查现状以及检验方法和流程,就如何进一步提高1∶10 000DLG成果检验效率与质量做了一些分析与探讨。