نتایج جستجو برای: داده های ndvi

تعداد نتایج: 523517  

Journal: :Remote Sensing 2014
Jorge E. Pinzón Compton J. Tucker

The NDVI3g time series is an improved 8-km normalized difference vegetation index (NDVI) data set produced from Advanced Very High Resolution Radiometer (AVHRR) instruments that extends from 1981 to the present. The AVHRR instruments have flown or are flying on fourteen polar-orbiting meteorological satellites operated by the National Oceanic and Atmospheric Administration (NOAA) and are curren...

Journal: :Remote Sensing 2013
Fan-Wei Zeng G. James Collatz Jorge E. Pinzón Alvaro Ivanoff

Satellite observations of surface reflected solar radiation contain information about variability in the absorption of solar radiation by vegetation. Understanding the causes of variability is important for models that use these data to drive land surface fluxes or for benchmarking prognostic vegetation models. Here we evaluated the interannual variability in the new 30.5-year long global satel...

Journal: :Remote Sensing 2016
Erica L. Garroutte Andrew J. Hansen Rick L. Lawrence

The Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) have gained considerable attention in ecological research and management as proxies for landscape-scale vegetation quantity and quality. In the Greater Yellowstone Ecosystem (GYE), these indices are especially important for mapping spatiotemporal variation in the forage available to migratory elk (Cervus e...

Journal: :Remote Sensing 2010
Chai K. Lim

Pathfinder Normalized Difference Vegetation Index (NDVI) derived from Channel 1 (Red) and Channel 2 (near-infrared) of Advanced Very High Resolution Radiometer (AVHRR) onboard NOAA 14 became abnormally high for the 10-day composite from February 11 to 20 in 1999 for Western Australia. There was a solar eclipse in the satellite path on February 16 about the same time when NOAA 14 was above the e...

2009
Temuulen Tsagaan Sankey Keith T. Weber

Extensive livestock production has been Mongolia’s major industry for centuries and traditional nomadic herding lifestyle and Mongolia’s expansive rangelands sustain this industry. After the democratic election and economic liberalization in 1992, formerly state-owned collectives were disbanded and Mongolia’s livestock population was privatized. There was no longer a state institution to formal...

2004
Alexia M. Kelley Howard E. Epstein Donald A. Walker

The active layer is the top layer of permafrost soils that thaws during the summer season due to increased ambient temperatures and solar radiation inputs. This layer is important because almost all biological activity takes place there during the summer. The depth of active layer thaw is influenced by climatic conditions. Vegetation has also been found to have a strong impact on active layer t...

Journal: :Environmental entomology 2016
Francis P F Reay-Jones Jeremy K Greene Philip J Bauer

A 3-yr study was conducted to determine the degree of aggregation of stink bugs and boll injury in cotton, Gossypium hirsutum L., and their spatial association with a multispectral vegetation index (normalized difference vegetation index [NDVI]). Using the spatial analysis by distance indices analyses, stink bugs were less frequently aggregated (17% for adults and 4% for nymphs) than boll injur...

ژورنال: :جغرافیا و توسعه 0
سیدحسین میرموسوی دانشگاه زنجان حمیده کریمی دانشگاه

یکی از مهم ترین پیامدهای خشکسالی، کاهش مقدار پوشش گیاهی است. با کاهش پوشش گیاهی، شرایط محیطی برای بروز مشکلات مختلف نظیر فرسایش خاک، افزایش میزان رواناب سطحی و خطر بروز سیل و... فراهم می شود. بر این اساس، ارزیابی اثرات خشکسالی بر روی پوشش گیاهی از اهمیّت زیادی برخوردار است. در این رابطه، استفاده از روش های سنجشازدورانعکاسی، جهت ارزیابی اثرات خشکسالی، بهعنوانیکی ازکارآمدترینروش هاشناختهشدهاست. در...

Journal: :Remote Sensing 2014
Fernando Sedano Pieter Kempeneers George Hurtt

A data assimilation method to produce complete temporal sequences of synthetic medium-resolution images is presented. The method implements a Kalman filter recursive algorithm that integrates medium and moderate resolution imagery. To demonstrate the approach, time series of 30-m spatial resolution NDVI images at 16-day time steps were generated using Landsat NDVI images and MODIS NDVI products...

Journal: :Ying yong sheng tai xue bao = The journal of applied ecology 2012
Xiao-Peng Sun Tian-Ming Wang Jian-Guo Wu Jian-Ping Ge

The MODIS-NDVI data from 2000 to 2009 were used to analyze the temporal dynamics and spatial distribution of the vegetation cover in the Beijing metropolitan region before and after the 2008 Olympics. During the study period, the proportion of the significantly increased pixels of NDVI occupied 20.7% while that of the significantly decreased pixels only occupied 4.1% of the total, and the decre...

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