北京地区Landsat 8 OLI高空间分辨率气溶胶光学厚度反演

卫星气溶胶光学厚度(AOD)反演中,传统暗目标方法在反射率较低的水体、浓密植被覆盖区域取得了较好效果,在反射率较高且结构复杂的高反射地表上空目前多采用深蓝算法,但存在空间分辨率较低,对细节分布描述性较差等问题。为解决这一问题,本文首先以5年(2008年—2012年)长时间序列MODIS地表反射率产品为基础,采用最小值合成法建立500 m分辨率逐月地表反射率产品数据集,然后利用地物波谱库中典型地物波谱数据,分析建立MODIS与Landsat 8 OLI传感器蓝光波段反射率转换模型,最后北京地区AERONET地基观测数据确定了气溶胶光学物理参数,并反演获取了北京地区上空500 m分辨率的AOD分布。为验证反演算法的精度,分别将反演结果同AERONET及MODIS/Terra气溶胶产品(MOD04)进行交叉对比,同时利用相关系数R,均方根误差RMSE,平均绝对误差MAE以及MODIS AOD产品预期误差EE共4个指标进行衡量。结果表明:算法反演获取的AOD与AERONET观测值具有较高的一致性,各指标分别为R=0.963,RMSE=0.156,MAE=0.097,EE=85.3%,稍优于MOD04产品(R=0.962,RMSE=0.158,MAE=0.101,EE=75.8%),并且有效的对比点数也高于MOD04。通过与地基观测相比,卫星遥感获取的高分辨率城市地区AOD精度可作为定量评估城市空气质量的有效依据。     

Species diversity and regeneration of native species in Pennisetum ciliare (buffelgrass) pastures from the thornscrub of Sonora,México

To examine the influence of buffelgrass land conversion and pasture management on native species diversity and regeneration patterns, we describe community attributes and population structure in four different active pastures in thornscrub vegetation from eastern Sonora, Mexico. We compare a relatively undisturbed thornscrub community with a contiguous five years old active pasture, to identify species able to regenerate under current management practices. Buffelgrass conversion has a significant influence on species diversity and other community attributes. Active pastures have lower species diversity, crown cover and basal area of native species than the studied native thornscrub. An active pasture subjected to heavy grazing and without management of the thorny legume, Acacia cochliacantha, showed the lower species diversity and an almost monospecific stand of this legume. It is likely that the reduction in species diversity is caused by the conversion process, inadequate management and regeneration barriers that limit seedling establishment in active pastures. Our data recorded eight native species (13%) that were able to regenerate in active pastures. However, the great majority of native species were unable to regenerate under pastures. This study shows that under current management, active buffelgrass pastures maintain only a small fraction of native species with regenerating populations in the thornscrub.     

Stability of arsenopyrite and As(III) in low-temperature acidic solutions

Arsenopyrite is one of the most important pri-mary arsenic mineral. In the Eh-pH diagram of the As-O2-S-H2O system, if the total arsenic concentration (TAs) is taken to be 0.75 mg/L, the total sulfur con-centration, 32 mg/L, the temperature, 25℃and the pressure, one atmosphere pressure for the discrimina-tion of arsenic species, it may be found that under hy-pergene conditions, arsenopyrite is a moderately stable mineral. Only in the strongly alkaline and reducing environment can arsenopy…     

杭州市典型雨转雪天气成因及预报模型

利用2008—2018年的NCEP(1°×1°)再分析资料、常规气象观测资料和降雪加密观测资料,选出杭州地区10次典型的雨转雪天气过程,从大尺度环流背景和动力、水汽以及热力因子等物理量场结构方面展开研究,最终得出杭州冬季典型雨转雪天气的预报模型:①大尺度环流配置需满足能为雨转雪天气的形成提供有利的水汽、动力抬升以及中低层上暖下冷的逆温或等温层结条件;②水汽和动力因子等物理量须满足产生纯雪的特定条件;③杭州温度层结须为T_(2m)≤1.5℃、T_(925)≤-4.0℃、T_(850)≤0℃、T_(700)≤-1.0℃和T_(500)≤-10.0℃。此外,进一步补充了杭州可能产生大雪甚至暴雪量级降雪的特定条件。最终选取2019年初的2次典型降水过程进行预报回报检验。     

快速有效的转换波共转换点叠加技术

转换波共转换点(Common Conversion Point简称CCP)叠加的关键在于CCP抽道集和非双曲线正常时差校正NMO(Normal MoveOut). 目前方法的精度限制了其在中-浅层或大炮检距情况下的应用. 我们对CCP叠加技术进行了系统研究,导出了新的CCP位置计算公式和非双曲线时距关系式,并给出了具体的CCP抽道集方法. 理论模型试验和实验资料处理表明本文方法精度高、简便易行,特别是对于中-浅层和大炮检距情况也能得到良好的叠加效果.     

CuInSe2太阳电池薄膜的制备技术及研究进展

着重介绍了CuInSe2的结构和光、电学特性；讨论了多各上薄膜沉积技术；评价了主要的合成装置及其作途；综述了制备CuInSe2太阳电池器件的工艺和材料，提出了一种能成功地生产大面积太阳电池薄膜的经济有铲的沉积技术。     

Model Simulations on the Variability of Particulate MSA to Non-Sea-Salt Sulfate Ratio in the Marine Environment

A box model was constructed to investigate connections between the particulate MSA to non-sea-salt sulfate ratio, R, and DMS chemistry in a clean marine boundary layer. The simulations demonstrated that R varies widely with particle size, which must be taken into account when interpreting field measurements or comparing them with each other. In addition to DMS gas-phase chemistry, R in the submicron size range was shown to be sensitive to the factors dictating sulfate production via cloud processing, to the removal of SO₂ from the boundary layer by dry deposition and sea-salt oxidation, to the entrainment of SO₂ from the free troposphere, to the relative concentration of sub- and supermicron particles, and to meteorology. Three potential explanations for the increase of R toward high-latitudes during the summer were found: larger MSA yields from DMS oxidation at high latitudes, larger DMSO yields from DMS oxidation followed by the conversion of DMSO to MSA at high latitudes, or lower ambient H₂O₂ concentrations at high latitudes leading to less efficient sulfate production in clouds. Possible reasons for the large seasonal amplitude of R at mid and high latitudes include seasonal changes in the partitioning of DMS oxidation to the OH and NO₃ initiated pathways, seasonal changes in the concentration of species participating the DMS-OH reaction pathway, or the existence of a SO₂ source other than DMS oxidation in the marine boundary layer. Even small anthropogenic perturbations were shown to have a potential to alter the MSA to non-sea-salt sulfate ratio.     

关于MapGIS数据文件转换中色库处理技术探讨

针对不同软件向MapGIS进行文件转换过程中遇到统一色库的问题,本文着重介绍了两种色库的转换方法,并编制了相应的程序,实例测试印证了该方法的正确性与可行性,从而解决了不同软件向MapGIS转换的颜色处理问题。     

MAPGIS的数据转换与使用技巧

数据的共享使用和充分利用软件的优势互补．优化数字化生产的工艺流程．是降低生产成本．提高劳动生产率的有效办法。     

全站仪数据格式转换程序设计与实现

在分析数据存储文件格式的基础上,设计了数据的读取算法,对观测数据进行自动化识别,生成标准记录格式的观测数据文件和CASS通用编码格式的展点数据文件,从而减轻了内业数据处理工作量,提高了工作效率。