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While EVI and LAI are the most widely used vegetation parameters which can be used for remote sensing phenology extraction, this paper aims at assessing the differences of phenology information extracted from EVI and LAI time series and exploring either EVI or LAI time series performs well for all vegetation types over a large scale. To achieve this, GLASS-LAI phenology product(GLP) was generated...
Modeling natural forest is challenging since the vertical and horizontal structural heterogeneity of variations of tree height, scatter shape, and pattern resulted from different tree species, growth stage, and environmental variables. The heterogeneous effect of mix-scene is not well understood quantitative so far, which might cause substantial uncertainty in the soil moisture and biomass estimations...
Synthetic aperture radar (SAR) raw signal simulation is very useful for validating SAR system design parameters, for testing the effectiveness of different processing algorithms, and for other applications. If a nominal sensor rectilinear line of flight is assumed, frequency domain raw signal simulation can be used to generate the raw data with high efficiency compared with time domain simulation...
To obtain downward longwave radiation (DLR) product at high resolution and good quality, a method of calculating global DLR was proposed. Global geostationary and polar-orbiting satellite observations were used to cover the whole world, and several DLR algorithms and two atmospheric datasets were combined used to satisfy different conditions. The global DLR at 5 km was produced using Multi-source...
Landscape heterogeneity is a common natural phenomenon but is seldom considered in current radiative transfer models for predicting the surface reflectance. This paper developed an analytical Radiative Transfer model for heterogeneous Agro-Forestry scenes (RTAF). The scattering contribution of the non-boundary regions can be estimated from the SAILH model as homogeneous canopies, whereas that of the...
There has been growing interest in the investigation of vegetation using polarimetric remote sensing techniques. During the past several decades, a number of theoretical models have been proposed to study the scattering mechanisms in the vegetation medium and are very useful for forest stand or short crops [1]–[4].
Figure 2 shows the observed gap fraction and gap size distribution along with the sampling line. According to the algorithms of LAIcc, LAIlx and LAIpl, the results are obtained using the observed gap fraction and gap size distribution. respectively. Although the difference between Ωee and Ωlx is only smaller than 0.1. the difference between LAIcc and LAIlx can reach up to 0.36. Path length algorithm...
In this study, a single-channel parametric model (SC-PM) algorithm were used to produce 300m LST product from HJ-1B IRS data. The NCEP atmospheric profiles and a parametric model were used for atmospheric correction. In order to improve the accuracy of the land surface emissivity (LSE), the 1km ASTER Global Emissivity Dataset (GED) and self-developed 5-day 1km vegetation cover product were used for...
A stripmap-mode raw data generator of an extended scene taking into consideration trajectory deviation with a non-zero squint angle is proposed. The approach utilizes a new approximation for trajectory deviations in the conical reference system. It relies on one-dimensional azimuth Fourier domain processing followed by range time-domain integration. Several simulation results are finally presented...
Mix-scene of forest with the combination of different land cover types, such as grass, or crop, in one pixel is common, especially for the low resolution SAR images. Various radar models have been developed through years. However, the heterogeneous effect of mix-scene is not well understood quantitative so far, which might cause substantial uncertainty in the soil moisture and biomass estimations...
Land surface temperature (LST) is a key parameter for a wide number of applications, which include hydrology, meteorology and model validation. In this paper a physical single channel algorithm was developed for retrieving LST from the Landsat 8 TIRS data. ASTER Global Emissivity Dataset (GED) and Vegetation Cover Method (VCM) were chosen to improve the accuracy of land surface emissivity and the...
The environment of Greater Mekong Sub-region (GMS) was highly payed attention to its economic development. Remote sensing technology was a useful tool for global and regional environment monitor. The fractional vegetation cover (FVC) with 30m spatial resolution for GMS was extracted from the HJ-1/CCD data in this study. The vegetation covers were highly for the entire GMS, and the spatial differences...
Vegetation fraction is an important index for sandy land evaluation, but it changes with time and precipitation obviously, especially the annual ephemeral plants. How to choose the best time for vegetation coverage to evaluate the sandy land degree is an imperative question. In this paper, soil adjusted vegetation index (SAVI), pixel dichotomy model and pixel unmixed model for multi-endmumber were...
Leaf area index (LAI) is a critical parameter in many terrestrial ecosystem models. Continuous LAI measurements from global sites are an important dataset for the validation of remotely sensed LAI products. However, the spatial scale mismatch between the site measurement and the product pixel grid hinders the utilization of multi-temporal ground LAI measurements. In this study, a pragmatic method...
This study analyzed the relationship between the spatial heterogeneity of land surface temperature (LST) and the spatial scale using the Thermal Airborne Hyperspectral Imager (TASI) and satellite-based Advanced Spaceborne Thermal Emission Reflection (ASTER) data. The spatial heterogeneity of LST was quantified using variogram modeling in univariate and multivariate method. The results show that in...
Fraction of Absorbed Photosynthetically Active Radiation (FPAR) is the fraction of the incoming solar radiation in the Photosynthetically Active Radiation spectral region that is absorbed by a photosynthetic organism. This biophysical variable is directly related to the primary productivity of photosynthesis and some models use it to estimate the assimilation of carbon dioxide in vegetation. The solar...
Leaf area index is a key parameter to describe physical and biological processes of plants. Remote sensing technology offers a new method to obtain LAI at regional scales, but it generally records plants information in horizontal. Therefore, the canopy reflectance is easier to reach saturation when plants growth flourished. This paper firstly defines the issues of canopy reflectance saturation, and...
HJ-1/CCD data has both high spatial resolution and high temporal frequency. By using NDVI time series and SVM classifier with HJ-1/CCD data source, this paper proposed a new resolution for land use classification of Dahuofang Reservoir, Liaoning Province, China. The validation result demonstrates that this resolution could obtain finer result than others.
Leaf area index is usually estimated by gap fraction measurement. The mean projection of the unit leaf area on a plane normal to view direction is dependent with the view zenith angle except the view zenith angle is equal to 57.5°. Researchers tried to use this particular angle to overcome the influence of the leaf inclination distribution function. However, the ring of 57.5° is relative to the normal...
Normalized difference vegetation index is a key parameter to describe physical and biological processes of plants. Vegetation compositing technology offers a new method to obtain NDVI products with special consistency and continuity. MODIS BRDF compositing scheme reduces angular, sun-target-sensor variations with use of a BRDF model, but the Walthall BRDF model inversion required at least five good...
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