Simulation of leaf area index and biomass at landscape scale

The method for simulating the temporal and spatial distribution patterns of leaf area index (LAI) and biomass at landscape scale using remote sensing images and surface data was discussed in this paper. The procedure was: (1) annual maximum normalized difference vegetation index (NDVI) over the landscape was calculated from TM images; (2) the relationship model between NDVI and LAI was built and annual maximum LAI over the landscape was simulated; (3) the relationship models between LAI and biomass were built and annual branch, stem, root and maximum leaf biomass over the landscape were simulated; (4) spatial distribution patterns of leaf biomass and LAI in different periods all the year round were obtained. The simulation was based on spatial analysis module GRID in ArcInfo software. The method is also a kind of scaling method from patch scale to landscape scale. A case study of Changbai Mountain Nature Reserve was dissertated. Analysis and primary validation were carried out to the simulated LAI and biomass for the major vegetation types in the Changbai Mountain in 1995.     

基于遥感和地面数据的景观尺度叶面积指数和生物量的模拟

The method for simulating the temporal and spatial distribution patterns of leaf area index (LAI) and biomass at landscape scale using remote sensing images and surface data was discussed in this paper,The procedure was:(1) annual maximum normalized difference vegetation index (NDVI) over the landscape was calculated from TM images;(2) the relationship model between NDVI and LAI was built and annual maximum LAI over the landscape was simulated;(3) the relationship models between LAI and biomass were built and annual branch ,stem ,root and maximum leaf biomass over the landscape were simulated;(4) spatial distribution patterns of leaf biomass and LAI in different periods all the year round were obtained.The simulation was based on spatial analysis module GRID in ArcoInfo software ,The method is laso a kind of scaling method from patch scale to landscape scale ,A case study of Changbai Mountain Nature Reserve was dissertated ,Aalysis and primary validation were carried out to the simulated LAI and biomass for the major vegetation types in the Changbai Mountain in 1995.     

Methods for calculating glacier area and length in a mountainous area based on remote-sensing data and a digital elevation model

In a mountainous region, the glacier area and length extracted form the satellite imagery data is the projected area and length of the land surface, which can’t be representative of the reality; there are always some errors. In this paper, the methods of calculating glacier area and length calculation were put forward based on satellite imagery data and a digital elevation model (DEM). The pure pixels and the mixed pixels were extracted based on the linear spectral un-mixing approach, the slop of the pixels was calculated based on the DEM, then the area calculation method was presented. The projection length was obtained from the satellite imagery data, and the elevation differences was calculated from the DEM. The length calculation method was presented based on the Pythagorean theorem. For a glacier in the study area of western Qilian Mountain, northwestern China, the projected area and length were 140.93 km2 and 30.82 km, respectively. This compares with the results calculated by the methods in this paper, which were 155.16 km2 and 32.11 km respectively, a relative error of the projected area and length extracted from the LandSat Thematic Mapper (TM) image directly reach to -9.2 percent and -4.0 percent, respectively. The calculation method is more in accord with the practicality and can provide reference for some other object’s area and length monitoring in a mountainous region.     

Detecting biophysical properties of a semi-arid grassland and distinguishing burned from unburned areas with hyperspectral reflectance

This paper examines the utility of hyperspectral remote sensing to detect fresh and dry biomass, water content and plant area index of burned and unburned grassland in southern California. Contrary to many previously published reports, the normalized difference vegetation index (NDVI, a vegetation greenness index) was not a good indicator of any of these important biophysical properties in either the burned or unburned area, especially after regeneration. Rather, the water band index (WBI, an index of water status in vegetation) showed better promise of estimating these biophysical properties in this semi-arid ecosystem. Despite the post-regeneration similarities in visual and harvested values of these two areas, we found that the full range of hyperspectral reflectance in ‘visible to infrared’ (400–1000 nm) wavelengths when used in a cluster analysis can readily differentiate the burned and unburned areas. This demonstrates the utility of hyperspectral remote-sensing in mapping subtle features that may not be detectable from conventional remote-sensing indices (e.g. NDVI) alone.     

遥感分景数据的剖分索引模型

随着空间技术和对地观测技术的飞速发展,海量遥感影像索引成为目前国内外学术界和应用部门面临的一大难题,地球剖分系统的产生为这一难题的解决开辟了新的途径。本文首先研究了遥感分景数据的特征和EMD全球剖分的特征,然后针对现有遥感影像数据索引方法的不足,提出了基于EMD剖分系统的三种索引模型:基于影像—面片映射关系的索引模型、基于EMD数据模型的索引和剖分数据标识索引模型,从三个不同的方面探讨了解决索引问题的方法和思路。并给出了利用遥感分景数据的剖分索引模型对线状对象和面状对象进行索引应用的实例。遥感分景数据的剖分索引模型的建立为遥感影像数据的高效存储和索引提供了一种有益的新思路。     

基于多源遥感的聚落与多级人口统计 数据的关系分析

在四川省市州、区县和典型村等三级尺度上,探讨了基于多源遥感的聚落面积与多级人口统计数据的关系。首先,从LANSAT TM影像中提取农村和城镇聚落信息,从Quickbird 影像上提取农村聚落及其房屋地基信息。其次,通过叠加统计得到各级统计单元内的聚落面积;再次,在四川省市州和区县尺度上,分别对城乡聚落面积和总人口数、城镇聚落面积和非农业人口数、农村聚落面积和农业人口数等进行相关性分析, 城镇聚落和非农业人口数的相关系数最高,分别为0.962和0.791,并建立了基于城镇聚落面积的非农业人口数估算模型,其模型的判定系数分别为0.926和0.625;最后,在村级尺度上,对农村聚落及其房屋地基面积与农村人口数之间的相关性进行分析,其相关系数分别为0.806和0.825,分别建立基于农村聚落及其房屋地基面积的农村人口数估算模型,其模型的判定系数分别为0.65和0.68。研究表明,LANDSAT TM适用于大尺度的非农业人口估算,估算效果随尺度的降低而有所降低;Quickbird适合于精细尺度的农业人口估算。     

基于ETM+与MODIS数据融合的伊洛河流域地表蒸散估算

MODIS数据时间分辨率较高,在对地能量和水分变化监测应用中具有不可比拟的优势。但其空间分辨率较低,混合象元效应显著,尤其在地表土地利用类型复杂和空间异质性较大时,会带来较大的误差。而ETM+数据具备较高的空间分辨率,但其单一的热红外波段导致反演的地表温度精度不高,且时间分辨率低,因而限制了在地表蒸散监测中的应用。本文探讨了将TM/ETM+与MODIS数据相融合估算区域地表蒸散的一种多尺度遥感方法,利用TM/ETM+计算得到的植被指数,基于空间增强方法将MODIS反演的地表温度尺度提高到30 m,并结合SEBS模型对伊洛河流域的地表蒸散进行了估算。验证与分析的结果表明,估算精度得到提高,研究区当日蒸散量在0～5.32 mm/d之间,空间分布具有明显的地域性差异,区域分布不均衡。     

基于过程模型的河北平原冬小麦产量和蒸散量模拟

本文结合作物参数的遥感信息反演和气象要素的空间尺度扩展方法 ,建立以GIS背景数据库为支撑的冬小麦生长模型 ,研究河北平原农田生态系统生物量和蒸散量的区域分布特征。结果显示 ,河北平原 1990年高产区主要集中在保定中南部、石家庄中部、邢台中部和邯郸东部的南北条带上 ,单产在 6 0 0 0～ 84 0 0kghm- 2 之间 ,廊坊东部、沧州大部分、衡水中部、邢台东部和西部太行山区等是低产区 ,单产低于 30 0 0kghm- 2 。总体而言 ,该地区实际产量与光温生产潜力对比仍有较大差距。在冬小麦生长期 ,蒸散量主要在 30 0～ 5 0 0mm之间 ,水分利用效率低于2 0kghm- 2 mm- 1,其中小于 8kghm- 2 mm- 1的概率分布占 4 2 %左右。农业水资源不足 ,水分利用效率低 ,是该地区冬小麦生产面临的严重问题。     

Extracting urban areas in China using DMSP/OLS nighttime light data integrated with biophysical composition information

DMSP/OLS nighttime light (NTL) image is a widely used data source for urbanization studies. Although OLS NTL data are able to map nighttime luminosity, the identification accuracy of distribution of urban areas (UAD) is limited by the overestimation of the lit areas resulting from the coarse spatial resolution. In view of geographical condition, we integrate NTL with Biophysical Composition Index (BCI) and propose a new spectral index, the BCI Assisted NTL Index (BANI) to capture UAD. Comparisons between BANI approach and NDVI-assisted SVM classification are carried out using UAD extracted from Landsat TM/ETM+ data as reference. Results show that BANI is capable of improving the accuracy of UAD extraction using NTL data. The average overall accuracy (OA) and Kappa coefficient of sample cities increased from 88.53% to 95.10% and from 0.56 to 0.84, respectively. Moreover, with regard to cities with more mixed land covers, the accuracy of extraction results is high and the improvement is obvious. For other cities, the accuracy also increased to varying degrees. Hence, BANI approach could achieve better UAD extraction results compared with NDVI-assisted SVM method, suggesting that the proposed method is a reliable alternative method for a large-scale urbanization study in China’s mainland.