...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>International journal of remote sensing >Variation in NDVI values with change in spatial resolution for semi-arid savanna vegetation: a case study in northwestern South Africa
【24h】

Variation in NDVI values with change in spatial resolution for semi-arid savanna vegetation: a case study in northwestern South Africa

机译：半干旱热带稀树草原植被NDVI值随空间分辨率变化的变化：以南非西北部为例

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Natural vegetation and crop-greening patterns in semi-arid savannas are commonly monitored using normalized difference vegetation index (NDVI) values from low spatial resolution sensors such as the Advanced Very High Resolution Radiometer (AVHRR) (1 km, 4 km) and Moderate Resolution Imaging Spectroradiometer (MODIS) (250 m, 500 m). However, because semi-arid savannas characteristically have scattered tree cover, the NDVI values at low spatial resolution suffer from the effect of aggregation of near-infrared and red energy from adjacent vegetated and non-vegetated cover types. This effect is seldom taken into consideration or quantified in NDVI analyses of the vegetation of semi-arid lands. This study examined the effect of pixel size on NDVI values of land-cover features for a semi-arid area, using the 1000 m, 250 m and 10 m pixel sizes. A rainy season Systeme Pour l'Observation de la Terre 5 (SPOT 5) High Resolution Geometric (HRG) image at 10 m spatial resolution was utilized. Following radiometric and geometric preprocessing, the 10 m pixel size of the image was aggregated to 250 m and 1000 m to simulate imagery at these pixel sizes, and then NDVI images at the spatial resolution scales of 10 m (NDVI_(10m)), 250 m (NDVI_(250 m)), and 1000 m (NDVIi_(1000M)) derived from the respective images. The simulation of the NDVI_(250 m) image was validated against a concurrent 16 day MODIS NDVI composite (MOD13Q1) image, and the accuracy derived from the validation was generalized to the NDVIiooom image. With change from low to high spatial resolution, extreme magnitude NDVI values shifted towards the centre (mode) of the resulting approximately Gaussian NDVI distributions. There was a statistically significant difference in NDVI values at the three pixel sizes. Low spatial magnitude vegetation sites (woodland, cropland) had reductions of up to 28% in NDVI value between the NDVI_(10m) and NDVI_(1000M) scales. The results indicate that vegetation monitoring using low spatial resolution imagery in semi-arid savannas may only be indicative and needs to be supplemented by higher spatial resolution imagery.
机译：通常使用来自低空间分辨率传感器（例如超高分辨率高分辨率辐射计（AVHRR）（1 km，4 km）和中等分辨率）的归一化植被指数（NDVI）值来监控半干旱稀树草原的自然植被和农作物绿化模式成像光谱仪（MODIS）（250 m，500 m）。但是，由于半干旱热带稀树草原通常具有分散的树木覆盖，因此低空间分辨率下的NDVI值会受到来自邻近植被和非植被覆盖类型的近红外和红色能量聚集的影响。在半干旱地区植被的NDVI分析中很少考虑或量化这种影响。这项研究使用1000 m，250 m和10 m像素大小检查了半干旱区域像素大小对土地覆盖特征NDVI值的影响。利用雨季的Systeme Pour l'Observation de la Terre 5（SPOT 5）高分辨率几何（HRG）图像，其空间分辨率为10 m。在进行辐射度和几何预处理之后，将图像的10 m像素大小聚合为250 m和1000 m，以模拟这些像素大小的图像，然后以10 m的空间分辨率比例（NDVI_（10m）），250拍摄NDVI图像m（NDVI_（250 m））和1000 m（NDVIi_（1000M））。针对同时存在的16天MODIS NDVI复合图像（MOD13Q1）验证了NDVI_（250 m）图像的仿真，并将从验证中得出的精度推广到NDVIiooom图像。随着从低空间分辨率到高空间分辨率的变化，极端的NDVI值朝着所得的近似高斯NDVI分布的中心（模式）移动。在三种像素尺寸下，NDVI值存在统计学上的显着差异。在NDVI_（10m）和NDVI_（1000M）尺度之间，低空间量级植被场所（林地，农田）的NDVI值降低了多达28％。结果表明，在半干旱稀树草原中使用低空间分辨率图像进行植被监测可能仅是指示性的，需要通过较高空间分辨率图像进行补充。

著录项

  • 来源
    《International journal of remote sensing》 |2013年第8期|2253-2267|共15页
  • 作者

    C. Munyati; G. Mboweni;

  • 作者单位

    Department of Geography and Environmental Science, School of Environmental and Health Sciences, North West University (Mafikeng Campus), Mmabatho, South Africa;

    Department of Geography and Environmental Science, School of Environmental and Health Sciences, North West University (Mafikeng Campus), Mmabatho, South Africa;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号