共查询到18条相似文献，搜索用时 328 毫秒
1.
为了更好应用国产高分辨率遥感影像监测评价南方路域植被环境,研究南方路域针叶植被叶面积指数遥感反演.该文以长益高速研究区域的高分六号影像(GF-6)为基础,提出了可适用于针叶叶片的LIBERTY+ SAIL耦合模型并结合多元线性回归、局部加权回归反演路域植被针叶LAI的方法.研究中以耦合模型模拟的冠层光谱反射率、GF-6影像和野外实测生化参数为数据源,通过相关性分析,将与LAI相关性较高的SAVI、RVI和EVI 3种植被指数作为反演因子,结合组合模型反演LAI并评定模型的反演精度.结果 表明,耦合模型对南方路域针叶植被LAI的估算精度整体较高,对比分析两种叶面积指数的组合预测模型,耦合模型结合局部加权回归组合反演LAI具有优越性,可更好地反演路域植被针叶LAI. 相似文献
2.
利用1982-2012年的GLASS LAI数据,结合世界粮农组织(FAO)2000年发布的全球生态环境分类图,对亚马逊热带雨林31年的植被变化进行了综合分析,采用点与面相结合的分析方法,全面地反映雨林植被的变化情况。不同于过去研究中固定研究范围或直接研究整个南美洲区域,本文采用动态静态边界相结合的方法,在考虑热带雨林动态范围变化的同时也强调研究区域的内部变化。结果显示,亚马逊热带雨林叶面积指数在31年中整体呈现波动变化,进入2000年以后,热带雨林范围内平均叶面积指数先下降后增加,整体相对稳定。在空间分布上,由于人类毁林开荒,巴西境内的热带雨林以及热带雨林部分边缘地带的叶面积指数在31年中明显下降,热带雨林东南边界持续收缩;除此之外,雨林内部的叶面积指数波动上升,这是受到全球气候变暖的影响。结果与过去的研究进行对比,具有较好的一致性。研究论证了利用具有中国自主知识产权的GLASS LAI数据可以进行长时间序列大尺度的地表植被状况监测。 相似文献
3.
4.
基于MODIS叶面积指数时序数据集,运用变异系数、Mann-Kendall趋势检验和相关分析等主要方法,对2001—2019年湖南省植被时空特征、变化趋势及其与气象因子的对应关系进行了研究。结果表明：1)湖南省叶面积指数保持在较高值,整体植被LAI呈增加趋势,速率为0.57%/10a;西部植被生长好于东部,高植被生长区及中高植被生长区占整个省域面积的80.5%;2)省内植被LAI与气象关系不显著,且与降水、气温呈正相关,与日照时数呈负相关。 相似文献
5.
光学与微波植被指数协同反演农作物叶面积指数的可行性分析 总被引：1，自引：0，他引：1
光学遥感是目前反演植被叶面积指数LAI（Leaf Area Index）的主要手段,但是当叶面积指数较大时存在光学遥感信息饱和、反演精度显著降低的问题。叶面积指数和平均叶倾角对光学、微波波段范围内反射和散射特性都有重要影响,主要表现在植被结构参数的变化可以引起冠层孔隙率和消光截面大小的改变。本文以典型农作物玉米为例,通过构建统一的PROSAIL和MIMICS模型输入参数,生成一套玉米全生长期光学二向反射率和全极化微波后向散射系数模拟库和冠层参数库。通过对模拟数据与LAI敏感性和相关性分析得出：（1）光学植被指数MNDVI(800 nm,2000 nm),在LAI为0—3时敏感,基于MNDVI与LAI的回归模型可以估算LAI变化 0.4的情况,RMSE是0.33,R2是0.958。（2）微波植被指数SARSRVI(1.4 GHz HH,9.6 GHz HV),在LAI为3—6时敏感,基于SARSRVI与LAI的回归模型可以估算LAI变化1的情况,RMSE为0.22,R2是0.9839。研究表明,采用分段敏感的植被指数,协同光学和微波遥感反演玉米全生长期叶面积指数是可行的。 相似文献
6.
叶面积指数LAI(Leaf Area Index)是表征植被冠层结构特征的一个重要参数，已经成为多个对地观测系统的陆表参数标准产品，也是定量遥感模型的重要输入参数。快速、准确地获取植被LAI对于开展遥感产品验证、促进遥感模型的发展具有极为重要的意义。随着传感器性能与应用软件功能扩展，智能手机已经成为植被LAI测量的新选择。然而，由于手机成像传感器窄视场角的限制，现有算法依赖于叶倾角分布函数为球型分布的假设，即G函数(单位叶面积在垂直于观测天顶角的平面上的投影)恒等于0.5。因而，传统算法无法解决植被叶倾角分布未知的情况。本文提出了一种基于形状匹配的G函数估算方法，基于有限长度方法和多幅影像间隙率，计算样方内的植被冠层聚集指数，利用泊松分布模型分别得到了植被冠层有效叶面积指数(LAIeff)和真实叶面积指数(LAItru)，并用黑龙江海伦农场两种农作物类型(玉米和大豆)的破坏性测量得到的时间序列真实LAI数据(LAIdes)对算法进行了验证。结果表明，算法改进之前的均方根误差(RMSE)分别是0.84(垂直拍摄)和1.33... 相似文献
7.
《测绘与空间地理信息》2013,(11)
遥感定量分析方法能够通过生物量相关因子直观反映路域植被的生长过程,为探索公路建设运营对自然环境的影响及其影响的复杂性提供强有力的技术手段。利用高分辨率IKONOS影像,研究两种遥感解译方法反演路域植被叶面积指数(LAI),对比分析其结果与精度,探索适用于路域生态环境这一特殊生态区域植被LAI的反演方法。研究表明,物理模型法较经验模型法更具有适普性和准确性,更适用于路域植被LAI的反演,精度更高。 相似文献
8.
9.
10.
11.
木里煤田地处青藏高原典型生态环境脆弱地带的大通河源头,本文以Landsat影像为数据源,基于归一化植被指数像元二分模型估算木里煤田矿区1990-2016年植被覆盖度,监测其动态变化及时空发展规律。研究发现,1990-2016年矿区裸土及低植被覆盖面积增加156.60 km^2,中植被覆盖面积增加153.37 km^2,高植被覆盖面积减少309.99 km^2。动态监测结果表明,1990-2016年木里煤田植被覆盖呈现严重退化趋势,退化最明显区域出现在矿区周边;时空格局变化分析结果表明,矿区植被覆盖等级逐渐向低植被覆盖等级转变,植被覆盖区域面积逐渐缩小。通过监测木里煤田矿区植被覆盖动态变化并分析其时空变化特征,为研究区生态环境修复,土地复垦等工作提供相关数据参考及技术支撑。 相似文献
12.
Pavel Propastin Stefan Erasmi 《International Journal of Applied Earth Observation and Geoinformation》2010
A time series of leaf area index (LAI) has been developed based on 16-day normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) at 250 m resolution (MOD250_LAI). The MOD250_LAI product uses a physical radiative transfer model which establishes a relationship between LAI, fraction of vegetation cover (FVC) and given patterns of surface reflectance, view-illumination conditions and optical properties of vegetation. In situ measurements of LAI and FVC made at 166 plots using hemispherical photography served for calibration of model parameters and validation of modelling results. Optical properties of vegetation cover, summarized by the light extinction coefficient, were computed at the local (pixel) level based on empirical models between ground-measured tree crown architecture at 85 sampling plots and spectral values in Landsat ETM+ bands. Influence of view-illumination conditions on optical properties of canopy was simulated by a view angle geometry model incorporating the solar zenith angle and the sensor viewing angle. The results revealed high compatibility of the produced MOD250_LAI data set with ground truth information and the 30 m resolution Landsat ETM+ LAI estimated using the similar algorithm. The produced MOD250_LAI was also compared with the global MODIS 1000-m LAI product (MOD15A2 LAI). Results show good consistency of the spatial distribution and temporal dynamics between the two LAI products. However, the results also showed that the annual LAI amplitude by the MOD15A2 product is significantly higher than by the MOD250_LAI. This higher amplitude is caused by a considerable underestimation of the tropical rainforest LAI by the MOD15A2 during the seasonal phases of low leaf production. 相似文献
13.
秦岭地区植被覆盖动态变化对其生态环境有重要影响。本文利用Google Earth Engine云平台,选取1986—2019年Landsat TM/OLI地表反射率数据,结合像元二分模型估算秦岭地区植被覆盖度(FVC);通过年际变化斜率、变异系数、Hurst指数等评价指标,对FVC的时空变化、稳定性和持续性变化进行分析。此外,探究FVC与气温、降雨的耦合关系,并分析土地利用变化对FVC的影响。结果表明:34年间,秦岭地区FVC整体上呈现良好的状况,中高等及以上植被覆盖区达73.11%;FVC由1986年的62.86%增长到2019年的70.01%,植被活动在不断增强;FVC的变异系数均值为0.34,标准差为0.45,其稳定性与其空间分布呈高度自相关性;秦岭地区的植被覆盖变化受气候变化和人为因素的共同影响。 相似文献
14.
Gap probability theory provides a theoretical equation to calculate fractional vegetation cover (FVC). However, the main algorithms used in present FVC products generation are still the linear mixture model and machine learning methods. The reason to limit the gap probability theory applied in the product algorithm is the availability and accuracy of leaf area index (LAI) and clumping index (CI) products. With the improvement of the LAI and CI products, it is necessary to assess whether the algorithm based on gap probability theory using the present products can improve the accuracy of FVC products. In this study, we generated the FVC estimates based on the gap probability theory (FVCgap) with a resolution of 500 m every 8 days for Europe. FVCgap estimates were validated with field FVC measurements of ImagineS from 2013 to 2015 for crop types. Two existing FVC products, Geoland2 Version1 (GEOV1) and Multisource data Synergized Quantitative remote sensing production system (MuSyQ), were used to inter-compare with the FVCgap estimates. FVCgap estimates showed a better agreement with field FVC measurements, with lowest root mean square error (RMSE) (0.1211) and bias (0.0224), than GEOV1 and MuSyQ FVC products. The inter-annual and seasonal variations of FVCgap estimates were also showed the most consistent with field measurements. 相似文献
15.
利用2000-2015年植被生长季(4~10月)MODIS/NDVI产品反演生成同时相的植被覆盖度数据,运用趋势性分析方法和皮尔逊相关系数法,进行了不同类型自然植被覆盖度时空变化特征及其与降水量、平均气温的驱动因素分析。结果表明从多年平均状态看,针叶林的植被覆盖度高于其他天然植被,灌丛类的最低,荒漠和灌丛类的植被覆盖度总体呈递增趋势;从年际尺度上看,草原和灌丛类植被对气温和降水量的响应规律大致呈反方向;不同类植被在春季(4月)对气温和降水量反映的差异性最大,与春季为新疆融雪高峰期有一定关系。 相似文献
16.
Linsheng Huang Furan Song Wenjiang Huang Jinling Zhao Huichun Ye Xiaodong Yang Dong Liang 《Journal of the Indian Society of Remote Sensing》2018,46(11):1907-1914
Vegetation index-based methods have been widely used to determine the leaf area index (LAI). Nevertheless, under the high canopy coverage, the estimation ability of current inversion models has been profoundly decreased, due to the “saturation” phenomenon. In this study, the LAI of maize was investigated under various growth conditions. Two new triangular vegetation indices were proposed to improve the inversion ability and estimation accuracy of LAI on maize. The triangle difference vegetation index (TDVI) and triangle ratio vegetation index (TRVI) were constructed, and their accuracies were compared with the present spectral vegetation index models. The result shows that TDVI and TRVI are highly linearly correlated with LAI. The coefficients of determination (R2) and root-mean-square errors are, respectively, 0.92 and 0.94, and 1.42 and 0.92 using the simulated data, while they are, respectively, 0.83 and 0.77, and 0.98 and 1.05 using the measured data. In comparison with other vegetation indices (e.g. MSR, MTVI2, RTVI), TDVI is better able to estimate the LAI of maize. Conversely, TRVI has better inversion ability when the LAI is more than 3. Overall, TDVI is an accurate and robust approach for estimating the LAI of maize. The proposed TDVI and TRVI can be jointly used to retrieve LAI at various canopy coverages. 相似文献
17.
采用遥感技术对矿区生态环境进行监测与评价,对矿区生态环境的保护和可持续发展具有重要意义。本文首先提出了一种遥感生态指数（RSEI）改进方案,除了采用原模型的绿度指标、湿度指标、热度指标及干度指标4个生态指标外,引入植被净初级生产力（NPP）指标,并对矿区生态环境进行各单生态指标评价分析,然后采用改进后的遥感生态指数,对神府矿区2000—2016年的生态环境变化进行综合评价。评价结果表明,2000—2016年,神府矿区的遥感生态指数呈整体升高趋势,RSEI增幅约为0.1/10 a,大部分区域植被生产力逐渐增强,生态环境得到恢复,生态环境质量逐渐提升。 相似文献
18.
A leaf area index is a key parameter reflecting the growth changes of vegetation and one of the most important canopy structural parameters for performing quantitative analyses of many ecological and climate models. Although using high-resolution satellite data and the radiative transfer model (RTM) can be used to generate high resolution LAI products, the RTM method has some problems because its temporal resolution is low, the input parameters are more appropriate for a physics model, and some parameters are difficult to obtain. Problems that urgently need to be solved include improving the temporal-spatial resolution for LAI products and localizing LAI products. To explore an applicable method for the high-resolution LAI products in a small basin and to improve the inversion accuracy, we propose an approach for GF-1 WFV LAI retrieval using MOD15A2 data and the measured LAI of the Poyang Lake watershed. Empirical models were used to retrieve high resolution LAI values, and the results show that these models are well designed for analyzing time-series satellite data. Good correlations were obtained between the NDVI of the GF-1 WFV data, the retrieved LAI values and the MODIS LAI data from samples acquired in both summer and winter. The exponential NDVI model obtained the best LAI value estimation results from the GF-1 WFV data (R2 = 0.697, RMSE = 1.100); the best synthetic validation of the RMSE is 0.883, close to the optimum model. Therefore, the retrieval results more fully reflect the growth process of the different features. This study proposed an upscale method for developing a high spatial resolution GF-1 satellite standard LAI products retrieval model using MODIS data. The proposed method will be helpful for efficiently improving the temporal-spatial resolution of LAI products to benefit the extraction of vegetation parameter information and dynamic land use monitoring. 相似文献