干旱对华北地区植被变化的影响

利用中分辨率成像光谱仪(moderate-resolutionimagingspectroradiometer,MODIS)归一化植被指数 (normalizeddifferencevegetationindex,NDVI)数据产品和气象站点的帕尔默干旱指数(thepalmerdroughtseverity index,PDSI)数据,分析了2001-2013年华北地区及3个主要地表覆盖类型区植被变化的时空特征和干旱的变化特征, 并以不同时间尺度分析了干旱对植被变化的影响.结果表明:1)华北地区植被NDVI空间分布差异较大,NDVI总体上 呈东南高、西北低的分布特点.2001-2013年,华北地区植被活动呈增强的趋势,其中秋季植被活动的增强趋势最明显. 2)2001-2013年,华北地区的干旱总体上有所减轻,其中秋季干旱减轻的趋势最明显.3)华北地区植被年际变化与干旱 有显著的正相关关系,干旱对植被生长状态有较大影响.北部草原区和中部落叶阔叶林带的植被年际变化与干旱的正相 关性显著;而南部农作物区不显著,干旱对农作物生长状态影响较不明显.4)在季节尺度上,华北地区夏季植被变化与干 旱的正相关性最为显著,夏季植被生长状态最容易受到干旱的影响;以16d的植被数据分析表明,NDVI距平值更适合 表征华北地区植被生长状态与干旱的关系.      

Simulation and evaluation of the quality and availability of typical GLI ocean image

ADEOS-II satellite will be launched in the near future. It collocates many remote sensing instruments in the same platform. Among them, Global Image (GLI) is considered to be a main sensor which will play a key role. In order to understand the characteristics of future GLI ocean color images, a simulation and evaluation of the quality and availability of GLI typical ocean image has been done. In the paper, we first introduce the simulation models briefly, and simulate typical cases of radiance images at visible channels, in which the radiance distribution is based on geographic location, the satellite orbital parameters and sensor properties. A method, complex signal noise ratio (CSNR) to evaluate the image quality and availability, is developed according to the characteristics of image. Meanwhile, a series of CSNR images are generated from the simulated radiance components for different cases, which can be used to evaluate the quality and availability of GLI images before the ADEOS-II is placed in orbit. Finally, the quality and availability of GLI images are quantitatively analyzed by the simulated CSNR data. The results will be beneficial to the people who are in charge of GLI mission or plan to use the data from GLI.     

基于RS与GIS的麻阳河黑叶猴自然保护区植被覆盖动态变化监测研究

为了研究麻阳河保护区植被覆盖度变化情况,采用2004、2007、2010年多源遥感影像的NDVI数据,运用arcgis软件计算出保护区植被覆盖度,分析麻阳河保护区植被覆盖度变化情况。结果显示,2004～2010年保护区植被覆盖变化总趋势是低、中低植被覆盖度往中、中高植被覆盖度转化,占保护区总面积的69.04%。受到保护区下游彭水电站施工影响,只有9.17%的中高植被覆盖度转化为中低植被覆盖度。保护区森林、灌丛植被覆盖面积大,植被覆盖度趋于正向转换,呈良性恢复趋势。     

高光效对吉林省玉米气候资源利用效率的影响

为研究在东北半干旱地区大田种植条件下,不同种植方式的玉米群体气候资源利用效率、干物质积累情况和产量等特征,为区域玉米高效栽培模式技术提供理论依据。2014—2016年,在吉林省公主岭市进行大田试验,选取先玉335为研究对象,通过田间对照试验方法,分别设置了垄向南偏西20°、种植间距为0.4～1.25 m的高光效和垄向南偏西20°的高光效小垄处理,研究了不同种植方式下玉米气候资源利用情况。结果表明：高光效处理与高光效小垄和对照比,有较高的气候资源利用效率,收获指数最高,产量最高,产量性状表现更好,抽穗之后的干物质积累速率更高。可见,高光效种植方式对于产量有提升作用;垄向调整和株行距共同作用对于干物质积累和雌穗性状有一定的影响,实际生产中可根据需求选择种植方式。     

基于透射率模型和极值先验的杂散光消除方法

针对杂散光对空间光学系统的影响,结合实际研究中光机结构无法更改,且无法精确估计系统点扩散函数的情况,提出了一种基于透射率模型和遥感图像极值先验知识的消除遥感图像杂散光的新方法。该方法能够有效地消除杂散光对遥感图像的影响,提高图像对比度,使图像细节变清晰。实验中使用多个图像清晰度评价函数对图像的清晰度进行了计算。实验结果表明,采用此方法使图像清晰度提高了15%以上。     

Remote sensing of environmental change over China: A review

China is a large country by area. In situ monitoring of the environment cannot meet the demand of the society. For large areas, remote sensing is the only viable technology for environmental monitoring of the entire area. Although satellite observation capabilities as well as remotely sensed data acquired on board of satellites from both within and outside China are widely available, research is rare that targets the entire territory of China for environmental monitoring. In this paper, the process of environmental change has been categorized into changes in driving forces, environmental change, materials transport and transformation, concentration and abundance change, exposure and infection change of human and ecosystems, and impacts. The potential in monitoring changes in these various aspects is assessed. The progress of environmental change monitoring over the entire territory of China is reviewed. It is suggested that at the methodological level, remote sensing should not only be applied to observation and experiments as well as understanding the change mechanism, but also be coupled with environmental simulation and forecasting so as to support environmental policy making. At the application level, remote sensing should be used beyond its traditional application fields to include species diversity, biological invasion, public health, air and water quality monitoring. Finally, at the technical level, systematic research should be devoted to the improvement of operational and automatic use of remotely sensed data.     

郑州市城镇用地遥感动态监测研究

随着我国城市化进程的加快，城镇建设中土地利用问题必将日益显现。加强城镇土地利用监测，对于确保在城镇建设中科学合理利用土地将起着不可低估的作用。通过对利用遥感测出的郑州市城镇土地利用变化情况的分析，得出利用遥感对城镇土地利用进行动态监测是一种较为科学的方法。     

Comprehensive analysis of the impact of climatic changes on Chinese terrestrial net primary productivity

Recent climatic changes have affected terrestrial net primary productivity (NPP). This paper presents an investigation of the impact of climatic changes on Chinese terrestrial vegetation NPP by analyzing 18 years’ (1982 to 1999) climatic data and satellite observations of vegetation activity. Results indicate that climatic changes in China have eased some critical climatic constraint on plant growth. (1) From 1982 to 1999, modeled NPP increased by 1.42%·a-1 in water-limited regions of Northwest China, 1.46%·a-1 in temperature-limited regions of Northeast China and Tibet Plateau, and 0.99%·a-1 in radia- tion-limited regions of South China and East China. (2) NPP increased by 24.2%, i.e. 0.76 petagram of carbon (Pg C) over 18 years in China. Changes in climate (with constant vegetation) directly contrib- uted nearly 11.5% (0.36 Pg C). Changes in vegetation (with constant climate) contributed 12.4% (0.40 Pg C), possibly as a result of climate-vegetation feedbacks, changes in land use, and growth stimula- tion from other mechanisms. (3) Globally, NPP declined during all three major El Ni-o events (1982 to 1983, 1987 to 1988, and 1997 to 1998) between 1982 and 2000, but Chinese vegetation productivity re- sponded differently to them because of the monsoon dynamics. In the first three events (1982 to 1983, 1987 to 1988, and 1992), Chinese vegetation NPP declined, while in the later two events (1993, 1997 to 1998) increasing obviously.     

Comparison study on water use efficiency of wheat flag leaf

wild species and cultivars were planted under irrigated and dryland field condition. LCA\|3 model photosynthesis apparatus was employed to measure flag leaf WUE. The results show that WUE of diploid and tetraploid increases as the wild species became cultivated species. WUE of flag leaf increases as the chromosome ploid increases (2\%n\%→4\%n\%→6\%n\%) in the wheat evolution. Among modern cultivars, WUE of most irrigated varieties is higher than that of dryland varieties.     

论基于遥感的矿区土地利用/覆盖分类体系

针对矿区 LUCC 研究中合理确定土地利用/覆盖分类体系的探讨。在国内外分类体系研究现状阐述的基础上,分析了现有土地利用或覆盖分类体系存在的问题,详细分析了基于遥感的土地利用/覆盖分类体系的必要性,提出了制定标准时应遵循的主要原则,最后针对矿区的特点提出了建立分类体系的两种模式。     

多方法集成的土地利用变化信息提取

由于影像噪声、变化信息自动发现方法、图像分割等因素对土地利用动态监测精度有较大影响,当前的动态监测是在变化信息自动发现的基础上,用手工交互式提取变化信息,但该方法不能满足大区域动态监测所需的效率.作者选择多种方法处理两时相遥感影像,以自动发现变化信息,用两种图像分割技术将变化信息自动分割成二值图像,并对多幅二值图像的像素灰度求平均,利用计算的阈值将像素分为目标、不确定类和背景,将与目标相邻的不确定类归入目标,再根据室内资料和野外验证,将不确定类归入目标或背景.用野外实测数据验证,该方法的精度可达91.73%,比常规监测方法(如光谱特征变异法)的精度高5%～6%,并具有较高的效率,能满足大区域动态监测的需要.     

西北地区植被覆盖时空特征及其对气候变化的响应

目的定量分析西北地区地表植被覆盖的时间变化与空间分布,为其合理开展农业生产,进行环境保护和生态建设提供科学的决策依据。方法利用西北地区1982—2006年GIMMS-NDVI数据,以绿度变化率和偏相关分析法为基础,分析了西北地区不同生态地理分区NDVI的年际变化以及植被覆盖变化对气候要素在空间上的响应。结果近25年来,高原植被覆盖整体呈波动增加的趋势。各生态分区的NDVI均呈增长趋势,并且随着湿润程度和温度的降低,年均NDVI随之减小;1982—2000年降水量在减小,但减小幅度不显著;气温呈显著上升趋势,年均NDVI与气温的相关性较好。结论西北地区的东南部和西北部地区水热组合条件相对于中部地区较好;植被覆盖较好的区域,其改善的趋势明显,相反则不明显;西北地区东部水热组合条件向不利于植被生长方向转变,而西部向利于植被生长的方向发展。     

NPP distribution related to the terrains along the North-South Transect of Eastern China

Vegetation net primary productivity (NPP) is defined as the accumulative amount of organic matters per unit area and time, which is calculated from the difference between accumulative photosynthesis and accumulative autotrophic respiration by green plants. Since the NPP reflects the physiological and ecological characteristics of the plants and the interactive results of the environmental factors, it is an important index to evaluate a structure of ecological system, functional features and …     

薄靶闪烁探测器荧光接收效率的Monte Carlo模拟

该文给出了一种闪烁探测器荧光接收效率的Monte Carlo模拟方法,模拟了光子在闪烁体中的输运及在闪烁体表面的反射和透射现象,考虑到光在闪烁体表面的漫反射和漫透射,采用Phong反射模型和Hall透射模型,计算了探测器的光阴极在不同方位时对光的接收效率。理论模拟结果表明,荧光的接收效率与闪烁体的表面粗糙度有关,在120°方向附近荧光的接收效率最大,与实验结果符合得较好。     

草原植被遥感监测方法研究进展

在回顾我国草原植被遥感监测方法的基础上,重点介绍目前农业部在草原植被遥感监测中所使用的方法及其局限性。提出我国草原植被遥感监测今后应关注和解决的重点问题,指出草原植被遥感监测方法的研究重点应集中在提高草原植被遥感监测的精度和方法标准化上,并建议应加强我国草原遥感监测和信息化管理平台的建设。     

基于土地利用与地表覆盖遥感信息的洪水过程模拟

基于数字流域平台,将遥感技术获取的土地利用和地表覆盖1km栅格信息与数字高程模型数据进行空间配准,由此直接提取新安江模型参数IMP(不透水面积比),并通过构建林地面积比与新安江模型参数SM(土壤自由水蓄水容量)的关系间接确定各子流域的SM值．汉江褒河流域24场洪水实例研究表明：采用半分布式水文模型,15场洪水的确定性系数增大,22场洪峰流量相对误差显著降低;SM对洪峰流量的影响要比对确定性系数的影响大．     

基于白光干涉与衍射实验的仿真研究

根据惠更斯一菲涅耳原理,应用MATLAB软件编程,模拟了白光通过单缝、双缝、多缝、光栅以及圆孔的干涉或衍射的光强分布图形,通过改变缝宽、缝间距、光强以及圆孔的大小,观察到干涉衍射条纹的相应变化,这与光学理论相符合.这种方法作为辅助教学手段,使抽象而复杂的物理现象变得直观、简单,有助于学生的理解,尤其是对于教学具有非常直观的作用.     

小蓬竹的水分利用效率

以小蓬竹为材料,研究其水分利用率的日变化、季节变化及其与主要环境因子的关系,以了解小蓬竹的水分利用状况,为其作为喀斯特地区恢复树种提供科学依据.结果表明:小蓬竹叶片水分利用效率日变化曲线在1月为单峰型;4月为双峰型;7月和9月早间最高,之后逐渐下降.1年中,夏秋两季水分利用效率较低(日均值分别为1.72,1.99μmol·mmol~(-1)),春季居中(日均值3.71μmol·mmol~(-1)),冬季最高(日均值5.74μmol·mmol~(-1)).不同月份水分利用效率日变化的主要影响因子为空气相对湿度、叶片温度以及气孔导度等;全年尺度上小蓬竹水分利用效率的主要影响因子为胞间CO_2浓度、气孔导度以及叶片温度.     

南京城市热环境与土地利用关系研究

通过Landsat/TM遥感影像反演获取了南京市1988、1998、2002和2010年的地表温度和热岛强度,并进行了城市热环境变化分析。利用NDISI建筑指数获取城市建设用地信息,然后讨论城市地表温度与建筑指数的定量关系。结果表明:归一化之后的南京次高温、高温与特高温呈现明显上升趋势。随着热岛强度的分级越来越高,建设用地面积也越来越大,从定量分析来看,建设用地与地表温度呈线性正相关关系。随着建设用地面积的增加,地表温度上升速率加快。     

内蒙古羊草草原返青期遥感识别方法研究

研究羊草返青期遥感识别方法对于模拟及预测内蒙古草原植被物候变化具有重要意义.为了有效识别内蒙古羊草草原的返青期,本研究基于250m分辨率的MODIS归一化差值植被指数(NDVI)时序数据,首先分别采用双高斯函数、多项式、S-G滤波3种拟合方法对原始NDVI时序数据进行重建,然后进一步分别采用最大斜率阈值法、动态阈值法及滑动平均法对重建的最优NDVI数据进行返青期识别,并利用33个样本点的返青期地面观测数据对遥感监测结果进行了地面验证.结果表明,"基于S-G滤波拟合的滑动平均法"是内蒙古羊草草原返青期的最佳遥感识别方法,可以此为基础开展内蒙古草原主要植被返青期的时空变化规律研究.