Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Evaluating Optical Remote Sensing Methods For Estimating Leaf Area Index For Corn And Soybean, Rohit Nandan, Varaprasad Bandaru, Jiaying He, Craig Daughtry, Prasanna Gowda, Andrew E. Suyker
Evaluating Optical Remote Sensing Methods For Estimating Leaf Area Index For Corn And Soybean, Rohit Nandan, Varaprasad Bandaru, Jiaying He, Craig Daughtry, Prasanna Gowda, Andrew E. Suyker
School of Natural Resources: Faculty Publications
The leaf area index (LAI) is a key crop biophysical variable influencing many vegetation processes. Spatial LAI estimates are essential to develop and improve spatial modeling tools to monitor vegetation conditions at large regional scales. Numerous optical remote sensing methods have been explored to retrieve crop-specific LAI at a regional scale using satellite observations. However, a major challenge is selecting a method that performance well under various conditions without local scale calibration. As such, we assessed the performance of existing statistical and physical approaches, developed based on parametric, non-parametric and radiative transfer model (RTM)-look-up-table based inversion, using field observations from …
Revisiting The Use Of Red And Near-Infrared Reflectances In Vegetation Studies And Numerical Climate Models, Garik Gutman, Sergii Skakun, Anatoly Gitelson
Revisiting The Use Of Red And Near-Infrared Reflectances In Vegetation Studies And Numerical Climate Models, Garik Gutman, Sergii Skakun, Anatoly Gitelson
School of Natural Resources: Faculty Publications
Surface reflectance data acquired in red and near-infrared spectra by remote sensing sensors are traditionally applied to construct various vegetation indices (VIs), which are related to vegetation biophysical parameters. Most VIs use pre-defined weights (usually equal to 1) for the red and NIR reflectance values, therefore constraining particular weights for red and NIR during the VI design phase, and potentially limiting capabilities of the VI to explain an independent variable. In this paper, we propose an approach to estimate biophysical variables, such as Leaf Area Index (LAI), Canopy Chlorophyll Content (CCC) and Fraction of Photosynthetically Active Radiation (FPAR) absorbed by …
Parameterization Of The Satellite-Based Model (Metric) For The Estimation Of Instantaneous Surface Energy Balance Components Over A Drip-Irrigated Vineyard, Marcos Carrasco-Benavides, Samuel Ortega-Farias, Luis Octavio Lagos, Jan Kleissl, Luis Morales-Salinas, Ayse Kilic
Parameterization Of The Satellite-Based Model (Metric) For The Estimation Of Instantaneous Surface Energy Balance Components Over A Drip-Irrigated Vineyard, Marcos Carrasco-Benavides, Samuel Ortega-Farias, Luis Octavio Lagos, Jan Kleissl, Luis Morales-Salinas, Ayse Kilic
School of Natural Resources: Faculty Publications
A study was carried out to parameterize the METRIC (Mapping EvapoTranspiration at high Resolution with Internalized Calibration) model for estimating instantaneous values of albedo (shortwave albedo) (αi), net radiation (Rni) and soil heat flux (Gi), sensible (Hi) and latent heat (LEi) over a drip-irrigated Merlot vineyard (location: 35°25′ LS; 71°32′ LW; 125 m.a.s. (l). The experiment was carried out in a plot of 4.25 ha, processing 15 Landsat images, which were acquired from 2006 to 2009. An automatic weather station was placed inside the experimental plot to measure αi, …
Tree Canopy Effect On Grass And Grass/Legume Mixtures In Eastern Nebraska, Michael El. L. Perry, Walter H. Schacht, Gregory A. Ruark, James R. Brandle
Tree Canopy Effect On Grass And Grass/Legume Mixtures In Eastern Nebraska, Michael El. L. Perry, Walter H. Schacht, Gregory A. Ruark, James R. Brandle
School of Natural Resources: Faculty Publications
A study to determine the feasibility of producing forage for grazing livestock under trees was conducted as a step toward evaluating the potential for silvopasture systems in the northern and central Great Plains. The effects of overstory leaf area index (LAI), percentage understory light transmittance (LT), and soil moisture (SM) on yield and crude protein (CP) of big bluestem [Andropogon gerardii Vitman; (BB)], smooth bromegrass [ Bromus inermis Leyss.; (SB)], and mixtures with birdsfoot trefoil [ Lotus corniculatus L.; (BFT)] were examined. The study was conducted in both Scotch pine (Pinus sylvestris L.) and green ash (Fraxinus …
Scaling Up Of Co2 Fluxes From Leaf To Canopy In Maize-Based Agroecosystems, Timothy J. Arkebauer, Elizabeth A. Walter-Shea, Mark A. Mesarch, Andrew E. Suyker, Shashi Verma
Scaling Up Of Co2 Fluxes From Leaf To Canopy In Maize-Based Agroecosystems, Timothy J. Arkebauer, Elizabeth A. Walter-Shea, Mark A. Mesarch, Andrew E. Suyker, Shashi Verma
School of Natural Resources: Faculty Publications
Carbon dioxide fluxes are being measured in three maize-based agroecosystems in eastern Nebraska in an effort to better understand the potential for these systems to sequester carbon in the soil. Landscape-level fluxes of carbon, water and energy were measured using tower eddy covariance systems. In order to better understand the landscape-level results, measurements at smaller scales, using techniques promoted by John Norman, were made and scaled up to the landscape-level. Single leaf gas exchange properties (CO2 assimilation rate and stomatal conductance) and optical properties, direct and diffuse radiation incident on the canopy, and photosynthetically active radiation (PAR) reflected and …