土壤铅含量高光谱遥感反演中波段选择方法研究

利用高光谱遥感数据进行了南京郊外土壤重金属元素铅的含量反演,由于高光谱数据波段众多,波段选择或变换至关重要。比较了基于次贪婪的前向选择模型的最小角度拟合和基于遗传算法进行波段选择的最小二乘和偏最小二乘拟合,结果发现基于遗传算法的偏最小二乘反演结果优于全波段的偏最小二乘,表明波段选择在高光谱反演重金属中是有益的。尽管采取了波段选择后的各方法在反演时均能达到70%以上的训练精度,但因遗传算法搜索的解空间范围更宽广,使得基于遗传算法的偏最小二乘优于前向选择模型的最小角度拟合。最后还比较了基于遗传算法的普通最小二乘和偏最小二乘拟合,结果表明偏最小二乘更优,因此在高光谱反演重金属含量当中,偏最小二乘精度较高,而在波段选择方法中,遗传算法更优。     

基于ALOS光学影像的2008年汶川地震震害信息提取

本文基于ALOS光学影像对2008年5月12日发生的四川汶川大地震灾区进行了震害信息提取。由于本次地震造成了大范围的山体滑坡,我们尝试利用震前和震后获取的ALOS/AVNIR-2影像进行滑坡区域信息提取。首先利用分级方法提取植被和水体信息,对植被和水体进行掩膜之后通过基于像元的分类将裸地信息从震前和震后的影像中提取出来,两幅影像中裸地信息的差异则被认为是滑坡。同时在被滑坡阻塞的河流地区,水平面的上升情况也被提取出来。除此以外本文利用由SRTM获得的DEM数据对坡度和滑坡发生之间的关系进行了研究。     

Recent Changes Occurred in the Terminus of the Debris-covered Bilafond Glacier in the Karakoram Himalayas Using Remotely Sensed Images and Digital Elevation Models (1978-2011)

Recent changes occurred in terminus of the debris-covered Bilafond Glacier in the Karakoram Range in the Himalayas, Northern Pakistan was investigated in this research. Landsat MSS, TM and ETM＋ images were used for this study. Digital elevation models derived from ASTER GDEM and SRTM were also utilized. Visible, infrared and thermal infrared channels were utilized in order to get accurate glacier change maps. Three methods were tried to map this debris-covered glacier in this research. The glacier has been mapped successfully and the changes in the glacier terminus from 1978 to 2011 have been calculated. Manual, semi-automatic and thermal methods were found to give similar results. It was found that the glacier has undergone serious ablation during this period despite of the fact that many of the larger glaciers in the Hindu Kush and Karakoram mountain regions in the Upper Indus Basin were reported to be expanding. The terminus has been moved back about 600 meters during this period and there was an abrupt change in the glacier terminus during 1990-2002. We propose that debris thickness is not the only factor that influences the glacier ablation but the altitude of the debris-covered glacier as well. Many glaciers in the Karakoram region reported to be expanding were having higher altitudes compared to the study area.     

三体散射长钉（TBSS）在C波段雷达中的应用研究

利用普洱CIND3830-CC天气雷达资料、地面观测资料进行统计分析,研究2004-2013年普洱C波段天气雷达中27次三体散射长钉(TBSS)的统计特征、地面降雹与TBSS的对应关系,并对TBSS在冰雹预警方面的应用进行探讨,结果表明:(1)C波段雷达中,产生TBSS的回波的反射率因子范围为55.0~68.4 dBz,70%的TBSS出现在反射率因子≥60 dBz时。(2)TBSS的维持时间为10~79 min,63%的TBSS维持时间超过20 min。(3)TBSS一般出现在4.0~9.5 km,最低出现在2.6 km,最高出现在11.4 km。(4)TBSS长5.6~22.4 km,宽1.5~14.6 km,TBSS宽度与强回波区径向外侧的60 dBz以上回波的面积成正比,但TBSS的长度与反射率因子核心的强度和宽度无明显对应关系。(5)出现TBSS时,59%的回波出现了降雹,11%的回波出现了强冰雹。(6)出现TBSS且出现降雹的过程中,TBSS预报冰雹的时间提前量为5~100 min,平均为34.5 min。(7)在出现TBSS且出现降雹的过程中,TBSS的宽度与冰雹的大小或降雹密度成正比。此外,分析了出现TBSS但未降雹的原因,找出了TBSS配合垂直液态水含量密度(D_(VIL))和45 dBz伸展高度、TBSS配合回波宽度和45 dBz伸展高度的预报冰雹的方法,在出现TBSS特征的回波中,上述方法的预报准确率分别达89%和94%(临界成功指数为0.89和0.94)。     

A Velocity Dealiasing Scheme for C-band Weather Radar Systems简

A dealiasing algorithm for radar radial velocity observed by C-band Doppler radars is presented as an extension of an existing S-band dealiasing algorithm. This has operational significance in that many portable and many commercial broadcast radars, as well as approximately one half of the Chinese weather radar network （CINRAD）, are C-band radars. With a wavelength of about 5 cm, the Nyquist interval of C-band radars is just about one half that of S-band radars （wavelength of about 10 cm） and thus has more velocity folding. The proposed algorithm includes seven modules to remove noisy data, find the starting radials, dealias velocities, and apply least squares error checking in both the radial and azimuth directions. The proposed velocity dealiasing method was applied to one widespread rain case and three strong convective cases from radars operating in China. It was found that, on average, 92.95% of the aliased radial velocity data could be correctly de-aliased by the algorithm, resulting in 96.65% of the data being valid.     

新疆谢米斯台地区小岩体型矿化遥感探测

中酸性小岩体易被地质填图遗漏,严重制约了该类型矿化的发现。在新疆西准噶尔谢米斯台地区找矿工作中,首先利用ETM+数据进行小岩体扫面,进而选取重点区采用ETM+和中巴资源卫星02B HR数据进行分辨率融合后解译、识别中酸性小岩体,并利用主成分分析法提取蚀变遥感异常,结合地质、化探信息综合分析后确定重点检查区域。利用此方法共解译出14个钾质花岗岩和3个黑云母花岗岩小岩体,这些小岩体大多被野外检查所证实。经野外检查发现了5处铜、金矿化点,证实了该方法的有效性。本研究中采用的方法可以为西部地区地质填图和中酸性小岩体型矿产资源勘查提供借鉴。     

遥感线性构造解译和分形统计方法在沂南金矿及外围的应用

文章以山东沂南金场—铜井矿区及外围为研究对象,利用ETM+遥感数据为基本信息源,首先对遥感影像进行假彩色合成、校正、去除干扰等处理;然后对影像做滤波处理以增强区域构造信息进行线性构造解译,运用分形几何学的原理和计盒维数法求得分维值,得出该区线性构造具有良好的统计自相似性和分形特征;最后综合分析线性构造分维值、岩浆岩资料、已知矿床(点)信息,确定7个成矿远景区,其中Ⅰ号远景区是最有前景的异常区。     

L波段雷达探测资料质量控制方法探讨

<正>目前各探空站L波段雷达—电子探空仪系统的投入使用实现了角度自动跟踪、自动测距、自动数据处理功能,在减少人为失误的同时大幅度提高了工作效率。但是常因复杂天气、探空仪器性能不够稳定等因素造成探测记录出现异常,为此结合基层探空站值班和报表预审中常见问题,总结高空资料质量控制的思路和流程,确保探空资料的完整性、准确性和代表性,为天气预报、气候分析、科学研究和国际交换,提供及时、准确的高空气象探测资料。     

基于经验模型的Hyperion数据植被叶绿素含量反演

对于反演植被叶绿素含量而言,基于Hyperion等高光谱传感器数据、利用经验方法建模是一种快速准确的方法。利用多种植被的实测数据以及Hyperion模拟数据,分析植被反射率及其变化形式与叶绿素含量的相关性,并进一步针对红边参数、植被指数等分析植被反射率与叶绿素含量的关系,选取最准确的经验建模方法。经过对比,改进的简单比值指数(modified simple ratio,MSR)与叶绿素含量相关性最高,其回归模型能比较准确地反演出叶绿素含量。通过Hyperion图像、利用MSR指数与实测叶绿素含量得到回归模型,建立区域叶绿素含量分布图;并对张掖地区植被叶绿素含量进行了反演,反演结果具有较高精度,相对误差低于5%。