Integration of Optical and Microwave Remote Sensing Data for Agricultural Land Use Classification

An agricultural land use classification of Oltrepo' Pavese region (in Northern Italy) is performed through integration of remote sensing data from optical and radar sensors. The source of optical data was a Landsat-TM image acquired on April 1994, while the source of microwave data was a contemporaneous image of the new radar sensor SIR-C/X-SAR which was flown on-board the Space Shuttle during an experimental mission over the chosen test site. Then, they were combined through calculation of the principal components of the multidimensional data sets and a final classification was carried out and compared with the classifications obtained from optical and radar recordings separately. Results showed remarkable improvement in the classification accuracy of seedbeds and uncultivated fields with radar recordings and of herbaceous crop type with integrated data. Potential ability of a multi-sensor classification and limits of a single-temporal approach are discussed.     

基于数字锁相技术的飞机货舱火灾烟雾光学参数方法研究*

为解决飞机货舱火灾光学探测易受环境杂光和空气中灰尘、水汽干扰,误报率高的问题,提出1种基于数字锁相的双波长火灾烟雾探测方法。利用数字锁相技术调制双波长光源,选择性地提取微弱光散射信号,并设计前、后双向散射光探测光路。采用常见火灾材料及干扰源进行真假火源实验,依据米氏散射理论及不同粒径气溶胶颗粒对不同波长光的散射效应差异,以不对称比（AR）和双波长光强比（DWIR）作为火灾检测参数对不同粒径颗粒进行区分,根据2种火灾检测参数建立数据样本,利用BP神经网络进行分析,并加入复合式传感器实验作为对比。研究结果表明:基于数字锁相技术的火灾烟雾光学探测方法能够在一定程度上区分火灾烟雾和干扰源,误报率小于3.5%。     

The Importance of Mixing Height in Characterising Pollution Levels from Aerosol Optical Thickness Derived by Satellite

In the present study the horizontal distribution of columnar aerosol optical thicknessderived at high spatial resolution from Earth observation satellite data in the Lombardy area (Italy) was converted to the horizontal distribution of optically effective aerosols concentration at the ground level. This was achieved by incorporating information on atmosphere's mixing height, at which pollutants released at ground level are vertically dispersed by convection or mechanical turbulence. The resulted fields compared favourably to pollutant concentration measurements provided by the ground stations. These results show that it is possible to calculate mean concentration fields by using the spatial distribution of aerosol optical thickness (AOT) measured by satellite normalized by the atmospheric mixing height. The advantage of satellites in measuring AOT is that they can capture all actual emissions compared to the models, which are based on inventoried data.     

基于气溶胶光学特性垂直分布的一次浮尘过程分析

为了进一步认识上海地区浮尘污染的垂直分布特征,利用地面微脉冲激光雷达(MPL)和CALIPSO星载激光雷达对2009年10月19日远程输送到上海的一次典型浮尘过程的气溶胶光学特性进行分析.结果表明,此次浮尘过程气溶胶层主要存在于2km以下低空中,气溶胶后向散射系数范围0~0.015 km-1·sr-1,MPL消光系数范围0~0.32 km-1.浮尘过程中消光系数先增加后降低,气溶胶层不断抬升.浮尘天气2km以下大气中存在大量小粒径气溶胶颗粒,而0~0.5 km近地面则以颗粒较大的气溶胶为主;2~10 km大气中仅存在少量不规则气溶胶,其中4~6 km高度范围的大气由不规则气溶胶和规则气溶胶混合组成,球型和非球型粒子均存在.CALIPSO星载激光雷达532 nm总后向散射系数和MPL归一化相对后向散射系数的垂直分布特征基本一致.CALIPSO和MPL获得的消光系数垂直分布均随着高度增加而减少,但消光系数值存在较大差异.两者结合起来可以较全面客观地对上海地区浮尘天气进行观测.     

Characterization of aerosol optical properties, chemical composition and mixing states in the winter season in Shanghai, China

Physical and chemical properties of ambient aerosols at the single particle level were studied in Shanghai from December 22 to 28, 2009. A Cavity-Ring-Down Aerosol Extinction Spectrometer（CRD-AES） and a nephelometer were deployed to measure aerosol light extinction and scattering properties, respectively. An Aerosol Time-of-Flight Mass Spectrometer（ATOFMS）was used to detect single particle sizes and chemical composition. Seven particle types were detected. Air parcels arrived at the sampling site from the vicinity of Shanghai until mid-day of December 25, when they started to originate from North China. The aerosol extinction,scattering, and absorption coefficients all dropped sharply when this cold, clean air arrived.Aerosol particles changed from a highly aged type before this meteorological shift to a relatively fresh type afterwards. The aerosol optical properties were dependent on the wind direction.Aerosols with high extinction coefficient and scattering Angstrom exponent（SAE） were observed when the wind blew from the west and northwest, indicating that they were predominantly fine particles. Nitrate and ammonium correlated most strongly with the change in aerosol optical properties. In the elemental carbon/organic carbon（ECOC） particle type, the diurnal trends of single scattering albedo（SSA） and elemental carbon（EC） signal intensity had a negative correlation. We also found a negative correlation（r =-0.87） between high mass-OC particle number fraction and the SSA in a relatively clean period, suggesting that particulate aromatic components might play an important role in light absorption in urban areas.     

江南造山带东段鄣源枕状玄武岩的年代学与构造属性研究

江南造山带东段鄣源地区广泛发育呈构造岩块产出的镁铁质岩浆岩,包括空间上密切共生的蚀变枕状-块状玄武岩、辉长岩、辉绿岩等。玄武岩地球化学特征上总体富集轻稀土,亏损重稀土和高场强元素(Nb,P,Ti),类似于岛弧环境下岩浆活动的产物。SHRIMP锆石U-Pb测年结果显示,枕状玄武岩形成于(832±19)Ma,与伏川蛇绿岩和庐山地区枕状玄武岩形成时代一致。结合区域资料,认为鄣源枕状玄武岩形成于弧后小洋盆环境,与其东侧的伏川蛇绿岩和西侧的庐山地区枕状熔岩同属新元古代中期弧后洋盆的产物。     

Synergetic analysis of springtime air pollution episodes over Gwangju, Korea

The characteristics of springtime aerosols,including their optical and microphysical properties,were analyzed for the months of March to May of 2009 in Gwangju(35.23°N,126.84°E),Korea.A high Light Detection and Ranging(LIDAR)-derived aerosol depolarization ratio(δ) of 0.25 ± 0.04 was determined on dust particles during the observation period.The?ngstr?m exponent values of the 440–870 nm wavelength pair(?_(440–870)) and single-scattering albedo at 675 nm(Ω_(675)) measured by a CIMEL sun/sky radiometer were 0.77 ± 0.19 and 0.95 ±0.01,respectively.The elevated dust layers reached a maximum elevation of 4 km above sea level.Anthropogenic/smoke particles that originated from highly populated/industrialized regions could be distinguished by their relatively smaller particle size(?_(440–870) ranged between1.33 and 1.36) and higher light-absorbing(Ω_(675) of 0.92 ± 0.01) characteristics.These aerosols are mostly distributed at altitudes 1.2 km.The root-mean-square deviation(RMSD) between the aerosol optical depth(AOD,τ) derived from LIDAR_((τ_(LIDAR))) and from the CIMEL sun/sky radiometer_((τ_(CIMEL))) varied with respect to the surface PM10 concentration.The RMSD between τ_(LIDAR) and τ_(CIMEL) was as low as 13% under lower PM_(10) concentration levels( 100 μg/m~3).In contrast,the RMSD between τ_(LIDAR) and τ_(CIMEL) increased three times(~31%) under high surface PM_(10) concentration levels(100 μg/m~3).These results suggest that the accuracy of τ_(LIDAR) is influenced by specific atmospheric conditions,regardless of its uncertainty.     

水文模型与生态环境发展纵览

水文模型是水文科学研究的重要方法.文章详细梳理了自1851年Mulvancy推理公式以来水文模型的发展历史,为原始萌芽时期、近代发展时期、现代变革时期三个发展时期,总结了21世纪以来水文模型研究的最新动态,绘制了水文模型发展的时间轴,对生态环境与水文模型的耦合进行了探讨,包括生态环境对人类的影响和水文模型对生态环境的影响,最后给出了未来水文模型发展趋势的展望及所要面对的主要难题;以期推动水文模型研究工作的进一步发展.     

中国气溶胶光学厚度的时空分布及影响因素分析

基于1980~2017年MERRA-2再分析产品中的气溶胶光学厚度（AOD）数据,结合趋势分析和时空地理加权回归模型（GTWR）等方法,分析中国AOD的时空变化特征,从时空异质性视角量化自然地理和人类活动对AOD的综合影响.结果表明,1980~2017年AOD以0.0028a^-1的速率呈显著上升趋势,而2009~2017年AOD以0.0083a^-1的速率呈显著下降趋势.2008年前后为AOD由升到降的转折期,可能与2007年生态文明建设和2008年全球经济危机有关.胡焕庸线以东地区为AOD高值区,以人为气溶胶为主,近40a来AOD值呈显著上升趋势;胡焕庸线以西地区为AOD低值区,以自然气溶胶为主,AOD值基本不变.气温、气压、黑炭气溶胶排放和硫酸盐气溶胶排放与AOD呈正相关,降水、风速、NDVI和GDP与AOD呈负相关.AOD与影响因子间的关系具有时空异质性.从时间变化来看,降水、风速、NDVI、GDP的回归系数具有一致性,而气温、气压、黑炭气溶胶排放、硫酸盐气溶胶排放在不同年份的回归系数有正有负;从空间变化来看,中国北方地区气温与AOD间呈负相关,南方地区二者呈正相关.     

徐州市气溶胶光学厚度与PM2.5相关性及年周期特征

基于徐州市2014～2017年气溶胶光学厚度(AOD)、地面监测站PM_(2.5)浓度及气象数据,构建经标高订正的AOD(AOD/H)与经湿度订正的PM_(2.5)(PM_(2.5)×f_((RH)))之间的5种不同类型的拟合模型,分析两者在不同季节的相关性;同时利用经验模态分解对AOD/H与PM_(2.5)×f_((RH))进行周期变化分析。结果表明:AOD与PM_(2.5)浓度直接相关程度较低,经过订正后两者的相关程度显著提高;选取乘幂模型为最优拟合模型,利用乘幂模型估计得到的PM_(2.5)浓度与地面监测的经湿度订正的PM_(2.5)浓度呈显著正相关,相关系数在四季分别达到0.752、0.650、0.808和0.942;利用经验模态分解分析得到AOD/H与PM_(2.5)×f_((RH))具有显著的年周期变化特征,均在冬季出现高值,后逐渐降低,在6月前后出现极小值,到秋季又逐渐增大;AOD/H与PM_(2.5)×f_((RH))年变化特征表现出很高的一致性(r=0.888),表明在徐州地区AOD/H对PM_(2.5)×f_((RH))在年周期尺度变化特征研究中能起到良好的指示作用。