Terrain Feature Canopy Modeling: Final ReportColorado State University, College of Forestry and Natural Resources, 1979 - Forests and forestry - 192 pages A thermal canopy signature model (TCSM) was developed to approximate the thermal behavior of a vegetation canopy by a mathematical abstraction of three horizontal layers of vegetation. Canopy geometry within each layer is quantitatively described by the foliage and branch orientation distributions. Canopy geometry, solar irradiance, air temperature, horizontal wind velocity, relative humidity, and ground temperature are used to calculate the energy budgets of average leaves within each layer. The resulting system of conservation equations is solved for the average layer temperature. This information, together with the angular distributions of radiating elements, is then used to calculate the thermal exitance as a function of view angle above the canopy. Optical diffraction techniques were developed and employed to measure canopy geometry. Solar radiation absorption with the vegetation terrain elements is calculated using a modification of a Monte Carlo model (SRVC) developed for the reflective energy regime. The models were applied to a lodgepole pine (Pinus contorta) canopy and the results for a diurnal cycle are validated with radiometric measurements. Simulated versus measured radiometric average temperatures of Layer 2 correspond approximately within two degrees centigrade. Simulated results suggest that canopy geometry can significantly influence the effective radiant temperature recorded by a sensor above the canopy as a function of view angle. (Author). |
Contents
Supporting Material for Thermal Exit ance | 2-46 |
A Comparison of Two Photographic Techniques | 3-5 |
Scene Radiation Dynamics Vol I | 3-59 |
3 other sections not shown
Common terms and phrases
absorption coefficient air temperature angle frequency average element temperature azimuthal branch tip C...CALCULATE calculated canopy element reflectances canopy geometry Canopy Model Colorado State University contact thermisters convectional deWit Diffuse/Direct Ratio element transmission elements in layer emissivity energy budget equation FORMAT 1X Fort Collins function of solar global solar irradiance ground hemispherical band horizontal inclination angle input J.A. Smith Kimes leaf area index lodgepole pine canopy mean canopy element mid-elements in layer needles optical parameters PGAP PHIT photographs Pinus contorta plant canopy prediction probability of gap proportion of absorbed radiation transfers radiometer relatively Sensitivity Analysis sensor simulated proportion simulated results solar radiation solar zenith angle spectral irradiance spectral reflectance spectral solar irradiance SRVC SRVC statistical ensemble surface temperature TCSM thermal canopy thermal flux density thermal models thermal radiation three canopy layers total solar transpiration U.S. Army vegetation canopies vertical spectral view angle w/m² water vapor diffusion wavelength wind speed