نتایج جستجو برای: ndvi
تعداد نتایج: 5798 فیلتر نتایج به سال:
In this paper the progress made in producing predictions of the Normalized Difference Vegetation Index (NDVI) over Kenya in the Greater Horn of Africa (GHA) for the October–December (OND) season is discussed. Several studies have identified a statistically significant relationship between rainfall and NDVI in the region. Predictability of seasonal rainfall by global climate models (GCMs) during...
The Consequences of Precipitation Seasonality for Mediterranean-Ecosystem Vegetation of South Africa
Globally, mediterranean-climate ecosystem vegetation has converged on an evergreen, sclerophyllous and shrubby growth form. The particular aspects of mediterranean-climate regions that contribute to this convergence include summer droughts and relatively nutrient-poor soils. We hypothesised that winter-precipitation implies stressful summer droughts and leaches soils due to greater water availa...
In semiarid or arid conditions, the change of root-zone soil moisture can be almost instantaneously reflected by vegetation through biophysical process. This study investigated feasibility of mapping root-zone soil moisture using MODIS-derived NDVI via statistic approach at three sites (New Mexico, Arizona, and Texas) selected from the Soil Climate Analysis Network (SCAN). These three sites rep...
In the last few years, Crimean-Congo haemorrhagic fever (CCHF) has been reported as an emerging tickborne disease in Turkey. This paper deals with the preparation of an early warning system, aimed to predict the beginning of the CCHF season in Turkey based on a clear, simple and repeatable remotely-sensed signal. Decadal (mean of 10 days) values of the normalized difference vegetation index (ND...
We evaluated the initial 12 months of vegetation index product availability from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Earth Observing System-Terra platform. Two MODIS vegetation indices (VI), the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI), are produced at 1-km and 500-m resolutions and 16-day compositing periods. This pape...
BACKGROUND Geographic distribution of West Nile virus (WNV) is heterogeneous in Iran by a high circulation in the southern-western areas. The objective of our study was to determine environmental and climatic factors associated with the risk of WNV equine seropositivity in Iran. METHODS Serological data were obtained from a serosurvey conducted in equine population in 260 districts in Iran. T...
Vegetation dynamics are an important topic in the field of global environment change, which is of great significance to monitor temporal–spatial variability of desertification at regional or global scales. Following the reported desertification reversion in the late 1990s in the Horqin Sandy Land, an issue was concerned for desertification control by decreased water availability. To detect the ...
We review the literature and find 16 studies from across Africa's savannas and woodlands where woody encroachment dominates. These small-scale studies are supplemented by an analysis of long-term continent-wide satellite data, specifically the Normalized Difference Vegetation Index (NDVI) time series from the Global Inventory Modeling and Mapping Studies (GIMMS) dataset. Using dry-season data t...
To evaluate accuracy of low resolution vegetation mapping for hydrological purposes, a comparative study of NDVI images derived from MODIS and Landsat 7 ETM+ data has been done. Main goal is to understand how effective MODIS images can be for vegetation characterization on large areas, as compared to the Landsat 7 ETM+ ones. In this paper a methodology is proposed with the aim of measuring the ...
A large-scale re-vegetation supported by the Grain for Green Project (GGP) has greatly changed local eco-hydrological systems, with an impact on soil moisture conditions for the Chinese Loess Plateau. It is important to know how, exactly, re-vegetation influences soil moisture conditions, which not only crucially constrain growth and distribution of vegetation, and hence, further re-vegetation,...
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