نتایج جستجو برای: ndvi

تعداد نتایج: 5798  

2006
M. K. Raynolds D. A. Walker H. A. Maier

The Circumpolar Arctic Vegetation Map (CAVM) was used to analyze the distribution of NDVI and phytomass in the Arctic, providing data for understanding arctic vegetation patterns, assessing change, and calibrating models. The dominant trend in the analysis of Normalized Difference Vegetation Index (NDVI) was a decrease from south to north, correlating with bioclimate subzones and vegetation uni...

2011
Heng Duan

Based on a long-term vegetation index dataset of NDVI and meteorological data from 68 meteorological stations in the Qinghai-Tibet plateau and their relations with major climate factors were analyzed. The results show the following: 1) The linear trends of temperature in the Qinghai-Tibet plateau indicate that the temperature in the plateau generally increased, but it rose faster in the last 20...

Journal: :ISPRS Int. J. Geo-Information 2016
Pengyu Hao Li Wang Yulin Zhan Zheng Niu

Most methods used for crop classification rely on the ground-reference data of the same year, which leads to considerable financial and labor cost. In this study, we presented a method that can avoid the requirements of a large number of ground-reference data in the classification year. Firstly, we extracted the Normalized Difference Vegetation Index (NDVI) time series profiles of the dominant ...

Journal: :journal of agricultural science and technology 2010
e. javadnia m. r. mobasheri gh. a. kamali

sensors onboard meteorological satellites such as modis and avhrr are able to collect information adequate in frequency but with low spatial resolution. the problem can be overcome, if one finds a way to increase the quality of the vegetation indices through searching in each individual pixel of the images, employing concurrent higher spatial resolution images. the objective of this study was t...

2011
Shushi Peng Anping Chen Liang Xu Chunxiang Cao Jingyun Fang Ranga B Myneni Jorge E Pinzon Compton J Tucker Shilong Piao

Using satellite-derived normalized difference vegetation index (NDVI) data, several previous studies have indicated that vegetation growth significantly increased in most areas of China during the period 1982–99. In this letter, we extended the study period to 2010. We found that at the national scale the growing season (April–October) NDVI significantly increased by 0.0007 yr−1 from 1982 to 20...

Journal: :Int. J. Applied Earth Observation and Geoinformation 2014
Bernt Johansen Hans Tømmervik

Several studies have shown a close relationship between vegetation fertility and different vegetation indices extracted from satellite data. The vegetation fertility in Arctic is at overall scales highly related to temperature. At lower scales surface material, snow cover, hydrology and anthropogenic effects (geese, reindeer) are determinant in constituting the different vegetation communities....

2004
G. J. JIA H. E. EPSTEIN D. A. WALKER

We analysed the Normalized Difference Vegetation Index (NDVI), calculated from biweekly NOAA Advanced Very High Resolution Radiometer (AVHRR) images for northern Alaska at both regional (latitudinal gradients) and site scales. Our objectives were to determine if tundra types and arctic subzones could be differentiated in terms of intra-seasonal patterns of greenness, and to construct the relati...

2003
D. O. FULLER M. FULK

Fire scars in Kalimantan, Indonesia were mapped using optical and thermal data from the NOAA-AVHRR satellite sensor. Forty-four high-resolution picture transmission images mapped at 1 km spatial resolution were selected for a period immediately after intense biomass burning from October–December 1997. Composite images of the Normalized DiŒerence Vegetation Index (NDVI), surface temperature (ST)...

2009
Carlos M. Di Bella Ignacio J. Negri Gabriela Posse Florencia R. Jaimes Esteban G. Jobbágy Martin F. Garbulsky Victor A. Deregibus

Information about forage productivity and its interactions with cultural practices or climatic variation is necessary to plan livestock management and to increase production without damaging the environment. Remote sensing provides a valuable data source to achieve these goals. Here we characterize forage production over a large region (92 million hectares) by analyzing spatial, seasonal, and i...

2016
Lijuan Wang Guimin Zhang Hui Lin Liang Liang Zheng Niu

The Normalized Difference Vegetation Index (NDVI) is widely used for Leaf Area Index (LAI) estimation. It is well documented that the NDVI is extremely subject to the saturation problem when LAI reaches a high value. A new multi-angular vegetation index, the Hotspot-darkspot Difference Vegetation Index (HDVI) is proposed to estimate the high density LAI. The HDVI, defined as the difference betw...

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