The FLuorescence EXplorer (FLEX) mission proposes to launch a satellite for the global monitoring of steady-state chlorophyll fluorescence in terrestrial vegetation. Fluorescence is a sensitive probe of photosynthetic function in both... more
The FLuorescence EXplorer (FLEX) mission proposes to launch a satellite for the global monitoring of steady-state chlorophyll fluorescence in terrestrial vegetation. Fluorescence is a sensitive probe of photosynthetic function in both healthy and physiologically perturbed vegetation, and a powerful non-invasive tool to track the status, resilience, and recovery of photochemical processes and moreover provides important information on overall photosynthetic performance with implications for related carbon sequestration. The early responsiveness of fluorescence to atmospheric, soil and plant water balance, as well as to atmospheric chemistry and human intervention in land usage makes it an obvious biological indicator in improving our understanding of Earth system dynamics. The amenability of fluorescence to remote, even space-based observation qualifies it to join the emerging suite of space-based technologies for Earth observation. FLEX would encompass a three-instrument array for m...
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As a case study, a reconstructed PAL NDVI time series during 1982 to 2001 is used to monitor vegetation cover change in the Heihe river basin. Linear regression is used to characterize trends in vegetation cover change. The yearly Maximum... more
As a case study, a reconstructed PAL NDVI time series during 1982 to 2001 is used to monitor vegetation cover change in the Heihe river basin. Linear regression is used to characterize trends in vegetation cover change. The yearly Maximum Normalized Difference Vegetation Index (MNDVI) in the Heihe river basin elicits an explicit inter-annual change in the period 1982 - 2001. An increase in MNDVI occurs in mid-basin oases manly, while a decrease in MNDVI is observed mainly in the mountainous and Alxa's natural oasis regions of the Heihe river basin. Precipitation is the major climate driving force for vegetation cover changes in the Heihe River Basin. Precipitation also elicits a lag with respect to the MNDVI with a length of one year. The MNDVI is sensitive to precipitation and its sensitivity decreases with increasing precipitation . Anthropogenic influence seems to increase the MNDVI in the oasis in the middle Heihe river basin. This increase results from i.e. oasis expansion,...
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Research Interests: Geophysics, Image Processing, Time Series, Biomass, Performance, and 23 moreSouthern Africa, Time series analysis, Geometry, Variability, Calibration, Regression, Ndvi, Geomatic Engineering, Root-Mean Square Error, Performances, Reduction, Accuracy, Vegetation, Radiometry, Geometric correction, Reflectance, Spot, Vegetation dynamics, Spatial resolution, Precision, Electrical And Electronic Engineering, Normalized Difference Vegetation Index, and Spectral Response
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Aerosol pollution attracts a growing interest from atmospheric scientists with regard to their impact on health, the global climate and vegetation stress. A hypothesis, less investigated, is whether atmospheric aerosol interactions in the... more
Aerosol pollution attracts a growing interest from atmospheric scientists with regard to their impact on health, the global climate and vegetation stress. A hypothesis, less investigated, is whether atmospheric aerosol interactions in the solar radiation field affect the amount of radiation absorbed by vegetation canopies and hence terrestrial vegetation productivity. Typically, aerosols affect vegetation canopy radiation absorption efficiency by altering the physical characteristics of solar radiation incoming on for example a forest canopy. It has been illustrated, that increasing mixing ratio's of atmospheric particulate matter lead to a higher fraction of diffuse sunlight as opposed to direct sunlight. It can be demonstrated, based on the application of atmospheric (MODTRAN) and leaf/canopy radiative transfer (LIBERTY/SPRINT) models, that radiation absorption efficiency in the PAR band of Picea like forests increases with increasing levels of diffuse radiation. It can be documented - on a theoretical basis - as well, that increasing aerosol loads in the atmosphere, induce and increased canopy PAR absorption efficiency. In this paper it is suggested, that atmospheric aerosols have to be taken into account when estimating vegetation gross primary productivity (GPP). The results suggest that Northern hemisphere vegetation CO2 uptake magnitude may increase with increasing atmospheric aerosol loads. Many climate impact scenario's related to vegetation productivity estimates, do not take this phenomenon into account. Boldly speaking, the results suggest a larger sink function for terrestrial vegetation than generally accepted. Keywords: Aerosols, vegetation, fAPAR, CO2 uptake, diffuse radiation.
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ABSTRACT Leaf modelling software and dataset
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Full Practical Seminar Package, with model source codes, templates and instructions for the Liberty and WinSAIL models. Tha package is a rar archive which can be downloaded.
A short overview of different Radiative Transfer Modelling techniques and approaches is given for leaves and canopies. An extended literature overview gives access to many models developed by several authors. Some basic principles in RTF... more
A short overview of different Radiative Transfer Modelling techniques and approaches is given for leaves and canopies. An extended literature overview gives access to many models developed by several authors. Some basic principles in RTF modelling are shortly outlined.
In former work (Khavanin Zadeh A-R, 2012), demonstrated that the NDAI (Normalized Difference Asymmetry Index) an index related to leaf structural asymmetry, responds significantly to increased levels of pollution in urban areas using an... more
In former work (Khavanin Zadeh A-R, 2012), demonstrated that the NDAI (Normalized Difference Asymmetry Index) an index related to leaf structural asymmetry, responds significantly to increased levels of pollution in urban areas using an imaging camera. Klumpp et al. (2006), demonstrated that it is possible to perform bio-monitoring based on the hypothesis that:”The relationship between leaf structure (mesophyllness) and reflectance (NDAI) allows to monitor leaf structural changes by measuring adaxial and abaxial leaf reflectance as a proxy for leaf structural changes. In the work presented here we go a step further in the sense that we use a leaf bifacial model (ABM, Baranoski G.V.G., 2006), to investigate the relationship between bifacial leaf morphology (its asymmetry) by means of its mesophyllnes, to relate this with the NDAI in function of wavelength. This approach should corroborate that the pollution effects measured by using the NDAI, are related to leaf structural adaptation...