玉门地区铁路防沙体系建设的研究

论文分析了戈壁风沙流区铁路沙害现状,提出了玉门地区铁路防护体系建设中树种选择的依据,并筛选了二白杨、沙枣、花棒、柠条以及线叶柳等一些适合该区铁路防护林营造的树种。研究结果还表明,在该地区的铁路沙害防治中,工程措施和生物措施相结合是一种行之有效的治理措施,"客土造林"和乔、灌、草相结合是提高铁路防护林效益的关键。该研究结果为今后该地区的沙漠化整治和铁路防沙体系的建设提供了一定的依据。     

苏宏图戈壁沉积物分形空间变异性及其成因

戈壁沉积物组分结构具有分形特征,能否利用分形特征及其变异性指示戈壁地表沉积物形成过程中的风沙作用目前认识不足.通过计算内蒙古苏宏图戈壁地表表层沉积物的分形维数值并分析了其空间变异性.结果 表明:沉积物分形维数值随0.050～0.179 mm跃移组分含量的增大而增大,随0.179～20.919 mm蠕移及风蚀残余组分含量...     

新疆东戈壁钼矿床地质特征及成矿热液作用阶段划分、矿物生成顺序研究

新疆东戈壁斑岩型钼矿床是西北地区发现的第一个特大型钼矿床,矿床产于下石炭统浅变质碎屑岩夹火山岩中,位于雅满苏大断裂附近.文章通过分析含矿脉体之间的交切关系及生成先后顺序,将东戈壁钼矿成矿期热液作用划分为4个阶段;根据金属矿物之间的穿插、交代、共边关系,确定了矿物生成的先后顺序.     

5 ka BP以来阿尔金山北缘冲洪积扇沉积环境变化和戈壁动力过程初步研究

中国西北干旱区有大面积的戈壁地貌,但对其形成过程的研究不多。阿尔金山北缘的沉积物记录着临近戈壁地貌的发育过程。选择甘肃敦煌南湖绿洲附近的山水沟剖面作为研究对象,在独立的光释光测年基础上,通过对比分析粒度特征、磁化率和有机碳同位素值变化,探讨5 ka BP以来阿尔金山北缘戈壁沉积动力过程及其环境控制因素。结果表明：戈壁发育进程具有波动性,戈壁沉积动力在百（千）年时间尺度上受到环境因素制约,在2.67～3.57 ka BP和1.65～1.95 ka BP干热气候条件下,沉积物搬运动力较弱,戈壁发育受限;在4.27～4.84 ka BP时期水量较大,戈壁发育范围较广,属于扩张阶段。这一结果初步揭示了戈壁地貌演化与气候环境变化的联系。     

干旱荒漠区隐伏金矿覆盖层中金的分布与迁移：以新疆金窝子金矿田210金矿带为例

以新疆金窝子金矿田210金矿带为例,实验研究了该区地气和土壤活动态测量等深穿透地球化学方法的效果。实验表明地气测量和土壤活动态测量可以有效地反映覆盖层下隐伏矿体。揭露矿体覆盖层的钻孔研究表明,金活动态形式具有“C”型分布特征。采集矿体上方地表异常位置土壤孔隙中地气、土壤样品,使用透射电子显微镜(TEM)实测样品中微粒物质的粒径、形貌和成分,在地气和土壤中观测到了Au-Cu、Au-Bi成矿元素纳米微粒,此微粒是形成地表深穿透地球化学异常的物质,来源于覆盖层下隐伏矿体。微粒到达地表,可以形成地气和土壤活动态异常。纳米微粒具有可从土壤颗粒表面分离的性质,在其向上迁移过程中,可以从吸附固定状态解吸,此性质可以用于解释活动态异常在钻孔垂直剖面上的“C”型分布。     

Dust sources in arid and semiarid China and southern Mongolia: Impacts of geomorphological setting and surface materials

Analysis of the geomorphological settings and surface materials in arid and semiarid China and southern Mongolia revealed that the dominant dust sources are ‘Gobi’ deserts and alluvial fans adjacent to Gobi deserts in the piedmonts of the Kunlun, Qilian, Helan, and Gobi Altai mountains. These areas have persistent supplies of dust-sized particles, deposited by intermittent floods from the mountains, and fine materials are also generated by weathering and aeolian processes acting on the coarse fractions of Gobi surfaces. Clear spatial differences in mineral types and contents and in the salt contents of surface materials also strongly affected the intensity of dust emissions. Inconsistencies in monitoring, simulation, and calculation of dust emissions in previous studies of Northern China and Mongolia may have been caused by insufficiently detailed considerations of variations in the geomorphological setting. Where the geomorphological settings in these areas are not considered in sufficient detail, deviations arise in the estimation and prediction of dust using current models. Although the present study did not quantify the persistence and replenishment of dust sources in the study area, our conclusions about the importance of geomorphology can improve future studies of dust sources and controlling factors, improve assessments of the effects of climate change on dust emissions, and facilitate the interpretation of paleoclimate records.     

The Cross-Correlation Function as a Tool for Detecting Source-Receptor Relationships: Application to Asian Dust Transport to North America

The cross-correlation function was used in conjunction with the daily values of the aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) to establish and qualify a source-receptor relationship between dust over the Gobi desert and the West Coast of the United States.An objective method that can be used to determine the trajectory of dust transport and the transportation time at different locations along the trajectory across the Pacific are presented in this report.The spring season was analyzed (March to May),and the results showed that dust reaches the western United States in approximately five to six days.Although dust transport from the Gobi desert was demonstrated in the present study,the proposed cross-correlation technique can be applied to other regions and can be used to obtain useful insights on relationships between major dust sources and downwind receptor locations utilizing remotely sensed dust estimates.     

基于敦煌戈壁站观测对几套再分析产品夏季地表感热通量的评估

西北干旱区是欧亚大陆夏季感热输送的高值区,此区域感热输送对东亚季风气候系统的变异有重要影响。然而,再分析资料的感热通量在此区域存在很大的不确定性,影响该地区感热变化对东亚区域气候影响的认识。本文基于敦煌戈壁站2001~2014年夏季的观测数据,评估了NCEP/NCAR、NCEP/DOE、ERA-Interim和JRA-55这4套再分析产品的感热通量。敦煌戈壁站的感热通量是根据敦煌戈壁站常规观测数据和Y08方案计算得到,代表敦煌戈壁站的实际感热。结果显示,戈壁站夏季感热多年平均约为85.7 W m-2,但受局地降水的影响存在较大的波动;再分析资料的感热通量之间存在很大的不确定性,与观测相比,ERA-Interim的感热通量在大小和变化上好于其他再分析资料,在没有局地性降水的影响时比较接近观测。进一步分析了再分析感热与观测差异的原因。研究表明,再分析资料中的地表风速和地气温差与粗糙度设置和热力参数化方案相关联。各再分析资料均不同程度地低估了敦煌戈壁站的地气温差(观测值约6.5°C),这主要是由于再分析系统中对戈壁下垫面的粗糙度设置偏高以及热力参数化方案不太适用于戈壁下垫面造成的。相对而言,ERA-Interim的参数化方案在戈壁下垫面优于其他再分析产品的参数化方案,使得ERA-Interim的地气温差相对其他再分析资料更接近实际观测,感热通量较为合理。     

敦煌戈壁不同近地层大气稳定度下的感热交换系数

首先利用空气动力学法,计算分析了敦煌戈壁2000年9月—2001年9月的感热交换系数Ch的特征,计算得到Ch的年平均值为0.00203±0.00045。敦煌戈壁的Ch在近中性和中性条件下(-0.01<ζ<0.01,ζ为Monin-Obukhov大气稳定度参数)为常数,Chn≈0.0020;在稳定条件下(ζ≥0.01),Ch比较小,随地表风速的增大而增大,趋于Chn,它们之间存在的关系是:Ch=0.0012 0.0003ln(V);在不稳定条件下(ζ≤-0.01),Ch比较大,随地表风速的增大而减小,也趋于Chn,它们之间存在的关系是:Ch=0.0026-0.0002ln(V)。本文还利用地表温度、一层气温和一层风速近似计算了总体Richardson数Rb,判定大气的层结稳定度,再根据该稳定度来选择感热交换系数。     

Numerical simulation of the critical scale of oasis maintenance and development in the arid regions of Northwest China

Oasis is a special geographic landscape among the vast desert/Gobi in Northwest China (NWC). The surface sensitive heat flux and latent heat flux at Zhangye Oasis during 1 to 11 August 1991 are simulated using the NCAR nonhydrostatic mesoscale model MM5 Version 3. The horizontal grid resolution is set as 1km. By comparing the simulation results with HEIFE observations, it is proved that the model can be used to simulate the surface energy and water mass exchange of arid and semiarid regions in NWC.Based on the above results, the influence of different oasis scales on the local atmospheric field near the ground surface, and the critical scale of oasis maintenance, in NWC are studied dynamically. The following conclusion is obtained: the local thermal circulation between the oasis and the desert/Gobi is formed in the oasis downstream if the oasis scale is larger than 4 km. This local thermal circulation between the oasis and the desert adjacent to the oasis helps to conserve water vapor over the oasis. At the sametime, it transfers the abundant water vapor from the oasis into the desert/Gobi near to the oasis to supply relatively plentiful water vapor for desert crops to grow on the fringe of the oasis. So, it is advantageous for oasis extension. However, if the scale of the oasis is smaller than 4 km, it is not easy for the local thermal circulation between the oasis and the desert/Gobi to take shape. This study provides a new standpoint for oasis maintenance and development.