最小二乘混合像元分解的端元丰度信息提取研究

针对无约束最小二乘混合像元分解算法提取地物端元丰度出现的局限性问题,通过野外实地采集的地物光谱数据建立研究区典型的地物波谱库,以Landsat OLI影像作为主要数据源,在经过Gram-Schmidt(GS)影像融合的基础上,利用纯净像元指数(PPI)及基于几何顶点的端元提取技术提取研究区典型地物端元,最后通过完全约束的最小二乘混合像元分解算法完成对研究区典型地物端元丰度的提取。结果较好地解决了无约束最小二乘混合像元分解算法提取的端元丰度信息出现负值的情况,并且提高了典型地物丰度信息提取的精度。完全约束最小二乘混合像元分解算法的RMSE误差均控制在0.174 913左右,在很大程度上提高了混合像元分解精度及实用性。     

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.     

兰州市冬季大气边界层结构特征的观测和数值模拟研究

本文利用甘肃省政府和中国科学院的科技合作项目"兰州市大气污染及对策研究"所获得的系留气球探空资料,并且结合数值模拟方法,对兰州市冬季大气边界层温度场特征进行了对比分析,结果表明:在没有特殊天气过程的典型冬季代表性时段,山谷城市兰州逆温边界层结构无论白天或夜间都存在,而且经常出现多层逆温和白天的脱地逆温情况,只有当冷空气过境时,逆温现象才减弱或消失;与观测结果相比较可以看出,数值模拟结果基本上反应了温度场的主要特征。     

夏季巴丹吉林沙漠残余层与深厚对流边界层的关系研究

利用2012年7月"巴丹吉林沙漠陆气相互作用及其对区域气候的影响研究"实验所得到的观测资料和中尺度气象模式WRF,对夏季巴丹吉林沙漠对流边界层高度发展的特征及其影响因素进行了研究。结果表明:(1)2012年7月在巴丹吉林沙漠连续观测到厚度超过3500 m的深厚对流边界层,其最大高度可达4000 m以上;当这种深厚对流边界层出现之前,当地中低层大气(1000~4000 m)存在近中性的残余层,而在没有近中性残留层出现时,即便地表感热通量较大,当天最大对流边界层高度却明显偏低;(2)WRF模式模拟结果表明残余层稳定度和对流边界层高度之间的负相关关系在空间区域成立,残余层位温直减率与当地对流边界层高度在时间和空间分布上都呈现显著的负相关关系;残余层位温直减率与对流边界层高度的空间相关系数最大值可达-0.51;(3)观测和模拟结果均表明残余层稳定度会直接影响由感热通量产生的对流边界层的发展效率,进而影响对流边界层的最大高度。通过研究发现,除感热通量外,近中性的残余层是巴丹吉林地区深厚对流边界层出现的关键条件之一。     

Evaluation of Haney-Type Surface ThermalBoundary Conditions Using a CoupledAtmosphere and Ocean Model

A coupled atmosphere-ocean model developed at the Institute for Space Studies at NASA Goddard Space Flight Center (Russell et al., 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat flux Q to air / sea temperature difference △T by a relaxation coefficient k. The model was initiated from the National Centers for Environmental Prediction (NCEP) atmospheric observations for 1 December 1977, and from the National Ocean Data Center (NODC) global climatological mean December temperature and salinity fields at 1° ×1° resolution. The time step is 7.5 minutes. We integrated the model for 450 days and obtained a complete model-generated global data set of daily mean downward net surface flux Q, surface air temperature TA,and sea surface temperature To. Then, we calculated the cross-correlation coefficients (CCC) between Q and △T. The ensemble mean CCC fields show (a) no correlation between Q and △T in the equatorial regions, and (b) evident correlation (CCC≥ 0.7) between Q and △T in the middle and high latitudes.Additionally, we did the variance analysis and found that when k= 120 W m-2K-1, the two standard deviations, σQ and σk△T, are quite close in the middle and high latitudes. These results agree quite well with a previous research (Chu et al., 1998) on analyzing the NCEP re-analyzed surface data, except that a smaller value of k (80 W m-2K-1) was found in the previous study.     

Carbonatitic Volcanic Genesis of Hetaoqing Fe-Cu Deposit in Central Yunnan, China

Abstract. The Kunyang rift on western margin of Yangtze Platform is a continental rift, and also a rare Precambrian Fe-Cu mineralization zone in China. The Wuding-Lufeng mineralization area in the middle section of the rift is an important part of the zone, and an elliptic-shaped volcanic collapsed basin, controlled by a ring fracture system with carbonatitic volcanic rocks mainly occurring along the northwestern edge of the basin. The Hetaoqing Fe-Cu ore deposit at the western side of the basin is hosted in carbonatitic volcanic rocks and pyroclastic sedimentary rocks. The original ore bodies occur as layers, bands and lenses conformable to the host carbonatitic rocks. The ores usually appear as massive, impregnated and granular in carbonatitic rocks, and as brecciform and sandy in pyroclastic sedimentary rocks. Ore-forming minerals are magnetite, hematite, chalcopy-rite, bornite, pyrite, carrollite, molybdenite, cobaltite and skinnerite, and secondary minerals limonite, chalcocite, azurite, malachite and tenorite. Gangue minerals are calcite, dolomite, ankerite, common hornblende, arfvedsonite, augite, aegirine-augite, albite, phlogopite, biotite, chlorite and apatite. Evidences of mineral chemistry, trace elements and isotopic ratios of ores, as well as geological features, suggest that the original ores are igneous in origin. Chemical features of magnetites in the deposit belong to carbonatite type, and are similar to those from the Bayan Obo carbonatites. The ores are rich in iron, titanium, rare earth elements, niobium, tantalum, gold, silver, phosphor and sulfur. These features indicate that the Fe-Cu deposit associated with volcanic activity in the Wuding-Lufeng basin is alkali-carbonatite volcanic type.     

Rhythmic Layering in the Apatite (-Magnetite) Deposit in the Fanshan Complex, North China

Abstract. The Fanshan complex consists of three (First- to Third-) Phases of intrusion. The First-Phase Intrusive is composed of rhythmic layers. The Fanshan apatite (-magnetite) deposit is situated near the top of no. 6 rhythmic Unit of the First-Phase Intrusive. Two sketch maps were drawn through the deposit along no. 25 cross-cut on 425 mL and no. 1 crosscut on 491 mL in the Fanshan mine. Through this mapping, a small-scaled rhythmic layering (called sub-rhythmic layering) was newly found. The sub-rhythmic layering consists of five typical rocks: biotite clinopyroxenite, biotite rock, biotite-apatite rock, alternation biotite-apatite rock and apatite rock. The thickness of layers varies from four millimeters to several meters. Six units of sub-rhythmic layering were distinguished. Each unit consists of biotite clinopyroxenite (or biotite rock and biotite-apatite rock) layer at the bottom and apatite rock layer at the top.
Major element compositions of biotite and clinopyroxene were analyzed. The trends of Mg/(Mg+Fe*+Mn) atomic ratio (Fe*: total iron) of biotite and clinopyroxene indicate that the magma evolved markedly from relatively magnesian bottom layer to less magnesian top layer in each sub-rhythmic unit. A general trend, however, through the whole sub-rhythmic layering sequence shows that the both minerals become relatively magnesian upwards. The hypotheses of liquid immiscibili-ty, gravitational settling and magma mixing are against with the results obtained in the present study. This study suggests that the apatite (-magnetite) deposit is formed through fractional crystallization process.     

地表油气化探异常的解释与评价

油气化探中地表地球化学异常大量呈环形分布。在二连盆地桑根达来工区进行地表化探中，发现不同地球化学指标形成的地球化学异常的空间分布上表现为正环形组合和反环形组合。文中结合石油地质条件，通过数字模拟和异常形成的时间序列分析得出：正环形异常组合表示油气向地表微渗漏持续进行，下部可能存在工业聚集的油气藏；反环形异常组合表示油气向地表微渗漏正在减弱，历史上普经存在的油气藏已经消失。     

交互四元体系Li~+,Mg~(2+)//SO_4~(2-),B_4O_7~(2-)-H_2O 288K时相平衡研究

采用等温溶解平衡法研究了288K时Li+,Mg2+//SO42-,B4O72--H2O四元体系的固液相平衡关系,测定了该四元体系在288K时平衡液相的溶解度和密度。依据实验测定的平衡溶解度数据及对应的平衡固相,绘制了该四元体系的平衡相图及密度组成图。研究结果表明:交互四元体系Li+,Mg2+//SO42-,B4O27--H2O288K时平衡相图中有2个共饱点,5条单变量曲线,4个结晶区对应的平衡固相分别为Li2B4O7.3H2O,Li2SO4.H2O,MgB4O7.9H2O和MgSO4.7H2O。