| 1. | Advances in drought monitoring by using remotely sensed normalized difference vegetation index and land surface temperature products
基于植被指数和土地表面温度的干旱监测模型 |
| 2. | Then based on the method of dimidiate pixel model , the current model is improved , and the model of deriving vegetation fraction from normalized difference vegetation index ( ndvi )
然后在像元二分模型的基础上对已有模型进行改进，建立用ndvi归一化植被指数估算植被覆盖度的模型。 |
| 3. | This technique is mainly involved two steps : 1 ) vegetation effects correction : we used ndvi ( normalized difference vegetation index ) derived from tm and avhrr measurements for spatial and temporal variations of vegetation covers at different scales
但由于电磁波与地表相互作用的复杂性，雷达后向散射系数除受地表介电常数(土壤水分)影响外，还受到地表粗糙度、土壤类型、植被覆盖以及雷达入射角、频率、极化等多种因素的影响。 |
| 4. | After analysis of tm / etm + data ' s advantage over the forest change detection , tasseled cap transformation , principal component analysis and normalized difference vegetation index were chosen to enhance the vegetation spectral information . expert classification system was adopted to extract the main tree species in the littoral shelter forest
在分析etm +数据在森林资源监测中的优势的基础上，通过缨帽变换、主成分分析和植被指数法增强植被光谱信息，结合专家分类系统对沿海防护林主要树种进行提取。 |
| 5. | The authors have developed a device for measuring the normalized difference vegetation index ( ndvi ) by using four specially designed photoelectric detectors ; the ndvi can reflect the growing information and seasonal nitrogen fertilizer requirement of crops , and offers guidance for rational application of nitrogen fertilization
文中提出了一种由4个专门设计的光电探测器直接得到归一化植被指数的测量方法，该参数能够反映作物的生长状态，知道不同季节的农作物对氮的需求量，对实施变量精准施肥具有重要的指导作用。 |
| 6. | Firstly , this dissertation estimated the size of carbon source ; sink and net carbon sink of farmland ecosystems in china costal regions ( including ten provinces ) with statistic data from 1981 to 2001 , which include data of crop yield and agricultural consumptions . then analyzed the temporal - spatial differences of carbon source , sink and net carbon sink of china costal farmland ecosystems . secondly , estimated npp ( net primary productivity ) of farmland ecosystems in china costal regions with per month noaa - avhrr ndvi ( normalized difference vegetation index ) data and estimation model
本文首先运用1981 - 2001年的统计资料(作物产量和各种途径的农业投入数据) ，对沿海十省区农田生态系统碳源汇及净碳汇进行了估算，并分析了其时空差异；然后运用1998年逐月ndvi数据通过建模对沿海地区农田生态系统npp进行了估算，并分析了npp分布与农田生态系统碳吸收的相关性；最后通过对农田生态系统碳源汇的影响因素分析，提出了不同的农田生态系统碳增汇减排技术。 |
