热红外核驱动模型在垄行植被热辐射方向性特征拟合中的精度分析     

曹彪  杜永明  卞尊健  董亚冬  赵峰  胡添  冉雪婷  秦伯雄  历华  肖青  柳钦火 《遥感学报》2021,25(8):1710-1721

垄行种植是果园及农作物的常见种植结构,其冠层比连续和离散植被冠层具有更强的热辐射各向异性,开展垄行植被冠层的热辐射方向性校正对干旱监测等应用具有重要意义。热红外核驱动模型是热辐射方向性校正的基础,但现有核驱动模型在垄行植被冠层中的拟合精度未被讨论过。本文以在法国波尔多获取的两组不同朝向葡萄园冠层航空实测方向性特征为基础,对比分析了现有8个模型的拟合精度（含隶属可见光近红外核驱动建模扩展框架的Ross-Li、LSF-Li模型及隶属热红外核驱动建模通用框架的Vinnikov、RL、Vinnikov-RL、Vinnikov-Chen、LSF-RL、LSF-Chen模型）,结果表明现有模型均无法拟合出垄行植被的行效应特征,精度整体较低（RMSE高达2 K,R²低于0.7）且各个模型之间的拟合能力差异小,现有热红外核驱动模型均不适用于垄行植被冠层,有待在核驱动建模通用框架下发展可刻画垄行特征的新核。  相似文献   

Sentinel-3 SLSTR数据的组分温度反演     

康童健  郭明珠  曹彪  任华忠  范闻捷 《遥感学报》2021,25(8):1671-1682

陆表温度是全球气候观测系统的基本变量。由于地表目标多数为具有三维结构、组成成分复杂、温度分布不均一的混合像元,因此相较于平均温度,组分温度具有更明确的物理意义和应用价值,对地—气相互作用过程和水分循环的定量分析研究具有重要意义。本研究针对Sentinel-3 SLSTR数据,基于CBT-P模型和CE-P模型构建了植被—土壤组分温度反演框架,并分析了劈窗算法和LAI对反演误差的影响。使用小汤山、漯河、塞罕坝3地实测数据进行结果验证,结果表明,5个验证点的植被组分温度反演结果的绝对偏差在0.1—1.6 K之间,平均绝对偏差为1.1 K,土壤组分温度反演结果的绝对偏差在0.5—1.4 K之间,平均绝对偏差为0.8 K,在中纬度的稀疏连续植被和垄行植被冠层中取得了较高的精度,初步证明了本研究提出的Sentinel-3 SLSTR双通道双角度地表组分温度反演算法的可行性。  相似文献   

面向地理国情监测的房屋建筑区树冠覆盖多特征协同提取     

陈根良  董胜光 《测绘通报》2021,(10):73-77

针对全国地理国情监测工作新增树冠覆盖提取这一全新的工作任务,本文通过深入分析房屋建筑区主要地物光谱特征和纹理特征,确定以光谱特征归一化植被指数（NDVI）,以及对比度（contrast）信息熵（entropy）两个纹理特征作为判断规则,按照面向对象的思路,设计了一种综合应用高分辨率遥感影像光谱特征和纹理特征的房屋建筑区树冠覆盖范围提取方法。试验结果表明,该方法能够自动提取房屋建筑区树冠覆盖范围,大幅降低了当前常用的目视解译方法的工作量,与采用单一影像特征的提取方法相比,本文方法能够有效地区分房屋建筑区内与树冠覆盖光谱特征相近的地物要素。  相似文献   

CLM4.5冠层截留方案的敏感性试验与改进          下载免费PDF全文

陈海山  穆梦圆  尹伊  朱司光  李兴  孙善磊 《大气科学学报》2019,42(3):334-347

为探究陆气系统对于冠层截留过程敏的感性,研究基于NCAR CAM-CLM陆气耦合模式探讨了截留参数对于全球陆地蒸发、降水、径流及气温的可能影响,揭示了冠层截留与植被光合作用之间的潜在联系。通过GLEAMv3.0a陆面蒸散发数据评估了CLM4.5冠层截留方案,并指出该方案高估了低茎叶面积指数植被的冠层蒸发,而低估了高茎叶面积指数植被的冠层蒸发。在CLM4.5中引入冠层截留偏差校正方案则可在一定程度上提高了全球林区冠层蒸发和陆面蒸散发的模拟能力。  相似文献   

Rainfall partitioning into throughfall,stemflow, and interception within a single beech (Fagus sylvatica L.) canopy: influence of foliation,rain event characteristics,and meteorology   总被引：2，自引：0，他引：2  

Jeroen Staelens  An De Schrijver  Kris Verheyen  Niko E. C. Verhoest 《水文研究》2008,22(1):33-45

While the hydrological balance of forest ecosystems has often been studied at the annual level, quantitative studies on the factors determining rainfall partitioning of individual rain events are less frequently reported. Therefore, the effect of the seasonal variation in canopy cover on rainfall partitioning was studied for a mature deciduous beech (Fagus sylvatica L.) tree over a 2‐year period. At the annual level, throughfall amounted to 71% of precipitation, stemflow 8%, and interception 21%. Rainfall partitioning at the event level depended strongly on the amount of rainfall and differed significantly (p < 0·001) between the leafed and the leafless period of the year. Therefore, water fluxes of individual events were described using a multiple regression analysis (r_a² > 0·85, n = 205) with foliation, rainfall characteristics and meteorological variables as predictor variables. For a given amount of rainfall, foliation significantly increased interception and decreased throughfall and stemflow amounts. In addition, rainfall duration, maximum rainfall rate, vapour pressure deficit, and wind speed significantly affected rainfall partitioning at the event level. Increasing maximum hourly rainfall rate increased throughfall and decreased stemflow generation, while higher hourly vapour pressure deficit decreased event throughfall and stemflow amounts. Wind speed decreased throughfall in the growing period only. Since foliation and the event rainfall amount largely determined interception loss, the observed net water input under the deciduous canopy was sensitive to the temporal distribution of rainfall. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Comparison of three models to estimate evapotranspiration for a temperate mixed forest   总被引：2，自引：0，他引：2  

Tingting Shi  Dexin Guan  Anzhi Wang  Jiabing Wu  Changjie Jin  Shijie Han 《水文研究》2008,22(17):3431-3443

Forest evapotranspiration is one of the main components in the regional water budget. A comparison between measured and estimated eddy covariance (EC) data, considering the Katerji–Perrier (KP), Todorovic (TD) and Priestley–Taylor (PT) actual evapotranspiration methods, was carried out. These models, relying on more easily obtainable data, are valuable when long‐term direct measurements are not available. The objective of this paper is to compare the effectivity of these three models. In this paper, experimental data were obtained within the temperate mixed forest of broad‐leaved and coniferous trees of the Changbai Mountains in northeastern China during the growing seasons of 2003 to 2005. The KP method gave the most effective values for half‐hourly and daily evapotranspiration computed by summing up half‐hourly estimates, and the TD method overestimated evapotranspiration by about 30%. The diurnal courses of estimated and measured evapotranspiration showed bell curves, similar to that of net radiation, except for a slight increase at about 14:30 solar time due to a peak value of vapour pressure deficit (VPD). For the case of daily evapotranspiration using daily mean micrometeorological variables, the PT method presented the closest values to the measurements. Accuracy of estimation related to VPD negatively (especially for VPD > 1·5 kPa). The KP parameters, considered to be vegetation dependent, were a = 0·545 and b = 1·31 at the experimental site. A constant PT parameter (α = 1·18) was applied to estimated evapotranspiration. Daily values of α responded to VPD (negatively) more strongly than to soil moisture (positively) in this forest. The experiment showed the inherent limits and advantages of the three methods. The KP method, a semi‐empirical approach, was preferred to estimate half‐hourly evapotranspiration. The TD method was a mechanistic approach to estimate reference evapotranspiration and always overestimated actual evapotranspiration. The PT method, being site dependent and the simplest approach, was effective enough to estimate large time‐scale (at least daily) evapotranspiration. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

近地机载激光雷达棉花LAI提取方法研究     

陈洪  韩峰  赵庆展  刘伟  张天毅 《干旱区地理》2017,40(6):1256-1263

棉花叶面积指数（LAI）是描述其长势的重要指标,准确获取冠层结构参数是叶面积指数反演的必要条件。以ScoutB-100油动单旋翼无人机为飞行平台,搭载RIEGL VUX-1激光雷达,精确获取棉花高密度点云数据,得到研究区棉田数字表面模型（DSM）和数字高程模型（DEM）,通过差值运算获得其冠层高度模型（CHM）,进而提取有效的冠层结构参数。利用相关性分析法选取相关系数大于0.2的激光穿透力指数（LPI）、回波点云密度（D）、孔隙率（f_gap）、归一化高程值（V_nDSM）构建棉花LAI反演模型,并与实测叶面积指数进行精度验证与评价。实验结果表明：模型估算的LAI与实测LAI之间的决定系数为0.824,均方根误差为0.072,验证了模型的可靠性。  相似文献   

用拱棚法对极干旱区沙地水分来源的定性分析   总被引：1，自引：1，他引：0  

李红寿  汪万福  张国彬  邱飞  詹鸿涛 《中国沙漠》2010,30(1):97-103

在潜水埋深超过200 m的敦煌莫高窟极干旱沙漠区,用拱棚法和微型空气湿度监测仪对流沙水分的时空分布格局进行监测,并对水分的来源进行分析。拱棚膜面凝结水分的持续抽取表明,在典型干旱气候条件下,有源源不断的沙地水分蒸发,其中1.25 g·m-2·d-1的水分在膜面凝结。沙地水分的时空动态分布格局表明,存在水分向上运移的温湿度条件。由此判定,除降水之外地下潜水蒸发是沙地水分最基础的来源。实验表明,干沙层虽然对沙地水分蒸发具有极强的抑制作用,但在升温过程中仍存在水分蒸发;在降温过程不但可从下层流沙吸收大量的水分,而且可吸收大气水分。沙地的蒸发量大于来自大气的吸湿量,总有少量的水分流失。沙地水分潜水来源的确定,不但对沙漠化的治理提供了新思路,而且对莫高窟文物的保护具有十分重要的意义。  相似文献   

计算机自动识别分类技术在森林遥感中的应用     

谈正  杜春华 《遥感学报》1988,(1)

本文叙述应用计算机自动识别分类技术在航天遥感图像中对森林资源进行分类的一些探索研究。本文介绍了采用自编程序“地理坐标系和图像坐标系的精密仿射变换”、“识别型增强技术”、“多光谱信息的特征提取”、“多光谱模糊算法聚类分析”等一系列算法后所取得的分类图像结果,与实地及目视解译相比较,森林分类相对精度达90％。  相似文献   

遥感模型多参数反演相互影响机理的研究   总被引：2，自引：0，他引：2  

姚延娟  刘强  柳钦火  李小文 《遥感学报》2008,12(1):1-8

遥感数据具有覆盖范围广、时间与空间分辨率高的特点,被广泛应用于提取区域范围内的一些重要的生物物理参数.为提高参数的提取精度,需要制定正确的反演策略.了解影响参数提取精度的因素、反演过程中各反演参数之间如何相互作用是制定合理反演策略的关键.本文通过数学推导与物理机理的分析,证明了影响参数反演精度的因素不但有冠层反射率数据的质量,还有反演过程中参与反演的未知参数的个数、参与反演的每个参数的敏感性及各个参数敏感性之间的相关性.最后通过对反演不同参数个数、不同数据质量进行了叶面积指数反演的精度分析,验证影响参数反演精度的各个因素.  相似文献