机载激光雷达技术在长江三峡工程库区滑坡灾害调查和监测中的应用研究

机载激光雷达技术是一种利用激光对地表三维坐标精确信息进行采集的新型遥感技术。本文以长江三峡工程库区滑坡灾害调查和监测应用为主要研究目标,通过对试验区的机载激光雷达数据的获取和处理,得到了精度很高的机载激光雷达DEM产品,并从定性和定量两个方面进行了机载激光雷达技术滑坡调查和动态监测应用试验。研究表明机载激光雷达山体阴影图能够直观表达微地貌形态;机载激光雷达坡度和地表粗糙度图像能够提供精确的微地貌特征量;利用多期机载激光雷达数据进行滑坡动态监测,可以掌握一定时间段内滑坡体的变形趋势和特征,并精确测算变形量。     

基于激光雷达遥感和参数化模式研究城市混合层的发展机制

利用北京大学的微脉冲激光雷达(MPL)观测的偏南气流条件下的混合层高度和夹卷层厚度探测资料,研究简单天气条件下城市混合层的发展机制并与GB94的参数化方案相互映证.通过激光雷达遥感的混合层高度和夹卷层厚度计算了混合层顶的夹卷率A,得到其平衡夹卷阶段的值为0.24.在不考虑机械混合前提下反演了地面感热通量,结果表明遥感的反演值与梯度法的计算值有系统性偏差,但总体上仍旧有较好的相关.偏差量的大小反映了影响混合层发展的机械湍流的参数B,进一步通过GB91模式的模拟确定该参数的最佳值约为3.5.在此基础上讨论了混     

武汉上空钠原子层结构短期演化特征

对1996年3月1日～3日钠荧光散射雷达获得的观测数据进行了分析与处理,得到了武汉（30#+[o]32'N,114#+[o]22'E）上空钠原子层结构的短期演化特征分布图,并对它作了初步分析。结果指出,武汉上空钠原子层结构具有显著的时空变化特点,钠原子数密度的变化在1 h之内可达50%。     

Mie 散射激光雷达探测大气气溶胶的进展

简要论述了激光雷达探测大气的优点,以及求解M ie散射激光雷达方程的理论方法,并阐述了国内外近20 a来M ie散射激光雷达探测大气气溶胶的主要成果,及其存在的问题。     

Airborne and lidar measurements of aerosol and cloud particles in the troposphere over Alert Canada in April 1986

As a component of the Canadian Arctic Haze Study, held coincident with the second Arctic Gas and Aerosol Sampling Program (AGASP II), vertical profiles of aerosol size distribution (0.17 m), light scattering parameters and cloud particle concentrations were obtained with an instrumented aircraft and ground-based lidar system during April 1986 at Alert. Northwest Territories. Average aerosol number concentrations range from about 200 cm^–3 over the Arctic ice cap to about 100 cm^–3 at 6 km. The aerosol size spectrum is virtually free of giant or coarse aerosol particles, and does not vary significantly with altitude. Most of the aerosol volume is concentrated in the 0.17–0.50 m size range, and the aerosol number concentration is found to be a good surrogate for the SO₄ ⁼ concentration of the Arctic haze aerosol. Comparison of the aircraft and lidar data show that, when iced crystal scattering is excluded, the aerosol light scattering coefficient and the lidar backscattering coefficient are proportional to the Arctic haze aerosol concentration. Ratios of scattering to backscattering, scattering to aerosol number concentration, and backscattering to aerosol number concentration are 15.3 steradians, 1.1×10^–13 m², and 4.8×10^–15 m² sr^–1, respectively. Aerosol scattering coefficients calculated from the measured size distributions using Mie scattering agree well with measured values. The calculations indicate the aerosol absorption optical depth over 6 km to range between 0.011 and 0.018. The presence of small numbers of ice crystals (10–20 crystals 1^–1 measured) increased light scattering by over a factor of ten.     

A vertical sounding of severe haze process in Guangzhou area

We detected a severe haze process in Guangzhou area with lidar and microwave radiometer, performed an inversion to get boundary layer height by wavelet covariance transform, and analyzed the correlation between meteorological factors of boundary layer and visibility from the perspective of dynamical and thermodynamic structures. Our results indicate that the boundary layer height shows significant daily changes, consistent with ground visibility variation. During the cleaning process, the boundary layer height exceeded 1 km; during severe haze, the height was only 500 m. Temperature gradient of 50–100 m, which was 30 h lag, was remarkably correlated with visibility, with the correlation coefficient of 0.77. High layer visibility(255 m) and low layer stability were significantly anticorrelation, and the maximum anticorrelation coefficient was up to-0.76 in cleaning days and-0.49 in haze days. In the related boundary layer meteorological factors, surface ventilation coefficient was linearly correlated with ground visibility, with the greatest correlation coefficient of 0.88. The correlation coefficients of boundary layer height, ground wind velocity, relative humidity and ground visibility were 0.76, 0.67, and-0.77, respectively. There was a strong correlation between different meteorological factors. The dominant meteorological factor during this haze process was surface ventilation coefficient. In the area without boundary layer height sounding, ground visibility and wind velocity could be used to estimate boundary layer height.     

合成孔径技术在光学领域的应用

介绍了合成孔径技术的发展及其基本原理,对国外合成孔径激光雷达的发展进行了综述,最后对合成孔径激光雷达的优势进行了分析.     

海洋内波活动对多波束测深影响因素的探讨

在多波束测深过程中,海洋内波对多波束测量精度产生影响的程度不同,由此会产生测量的地形出现起伏、扭曲等非正常现象。综合国内外的研究现状,本文大致阐述了目前海洋内波的研究进展,以及海洋内波成因和影响方式的研究程度,对海洋内波的主要基本特征有了一定程度的认识。基于实例分析,对试验海域海洋内波产生的原因进行了合理猜想。本文的分析研究对多波束测深工作具有一定的指导意义。     

基于光谱分层的浅海水深遥感反演方法

卫星水深反演是水深测量的一种重要手段,其中Stumpf比值算法和Lyzenga多项式算法应用广泛并诞生了大量改进算法,但这些算法没有顾及不同光谱的测深极限与适用范围,为此本文提出一种基于光谱分层的水深反演方法。首先,根据红、绿、蓝光谱对水体的穿透能力差异,提出一种基于影像本身的无参数光谱分层策略,提取红光层、绿光层、蓝光层;然后,根据不同光谱层的波段测深性能,分光谱层构建水深反演优化模型,获取浅海水深反演结果。以我国南沙海域长线礁和美属维尔京群岛巴克岛为实验区,本文方法对经典Stumpf比值算法和Lyzenga多项式算法进行改进后,水深均方根误差、平均绝对误差、平均相对误差分别降低了0.41～0.89 m、0.35～0.65 m、4%～19%,尤其在红光层,即水深较浅区域,平均相对误差降低了58%～149%,精度提升明显。因此,改进算法在提高卫星水深反演效果方面具有可行性和有效性。     

顾及局部地形改正的GGM海底地形反演

研究了顾及局部地形改正的GGM(gravity-geologic method)海底地形反演方法,采用该方法反演了印度洋Rodriguez三联点区域的1'×1'海底地形模型,说明了反演计算过程及结果的有效性。同时将该方法应用于南中国海内4°×4°区域的海底地形的反演。与船测海深比较发现,在研究区域内,GGM方法反演得到的海深模型精度优于ETOPO1模型,并且在南中国海研究区域内,改进方法大大提高了海底地形的反演精度。