FASST Vegetation Models

Abstract

The one-dimensional dynamic state of the ground model FASST (Fast All-season Soil Strength) is a state of the ground model developed by Frankenstein and Koenig (2004) as part of the Army's Battlespace Terrain Reasoning and Awareness (BTRA) research program. In its original form, the only effects vegetation had on FASST were to change the surface albedo and emissivity. Recently, a two tier, multilayer vegetation algorithm was added. These can be implemented separately or together. Both alter the soil surface energy and moisture budgets. In this report we will discuss the energy balance equations used to solve for the low vegetation, canopy and ground temperatures. In solving these equations, the effects of precipitation interception and soil moisture modification attributable to rootuptake are incorporated. DISCLAIMER:The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. FASST Vegetation Models iii CONTENTS

Development and validation of a coupled heat and mass transfer model for green roofs

“…Despite irregularities and amplitude variations of the temperature, the mean difference is 0.8°C, and 80% of the computed temperatures are significantly close to the experimental measurements with a relative precision of ±10% throughout the period under review, which highlights the accuracy of the model for predicting changes in the soil temperature over a long period (19 days). We also observed that, in contrast to other models [14,15,17], this model accurately predicts the temperature at night.…”

“…(14) and (27) are discretized using the implicit finite difference method, which has excellent stability and convergence. In contrast, the shortwave radiation and the latent terms are linearized at the iteration m using the same method performed in [17]:…”

“…To validate the model experimentally, the numerical results are compared with experimental data obtained from a one-tenth-scale model built at the University of La Rochelle in France. Table 1 summarizes various existing green roof models [13][14][15][16][17][18][19][20], which differ in their approaches. For example, some models treat the air inside the foliage canopy as a thermal zone that is renewed by urban air [18] or as a mixture with constant proportions below the aerodynamic boundary layer that is formed by the air flow over the vegetation [15,21].…”

Substrate Depth, Vegetation and Irrigation Affect Green Roof Thermal Performance in a Mediterranean Type Climate

“…The internal boundary conditions were set as 21 • C for heating and 20.9 • C for cooling. The energy fluxes (Equations (1)- (6)) in Sailor's model [28] were developed from FASST vegetation model by Frankenstein and Koenig [36]. Sailor's model highlights two main fluxes: one for the soil (substrate) layer (Equation (1)) and the other for the vegetation (Equation (4)).…”

Phase change and thermal performance analysis for green roofs in cold climates

“…On the other hand, the computational models include heat and moisture transfer in the soil and radiant heat exchange in the canopy layer, as well as the analysis of the growth substrate in green roofs to quantify the possible reduction [1,17,19]. Among them, the most commonly used and comprehensive green roof model is the Fast All-season Soil STrength (FASST) model, established by Frankenstein and Koenig [20,21]. A large number of researchers were based upon this model to conduct analysis and simulation of green roofs [22,23].…”