Evaluating the Parametrizations of Pressure-Gradient Interaction Terms in Higher-Order Closure Models for Airflows in and Above Plant Canopies

The parameterizations of pressure-gradient interaction terms in both second-order and third-order closure models that have been applied to study airflows in and above plant canopies are largely based on results for the atmospheric boundary layers or engineering flows. Due to the lack of experimental data, such parameterizations have not been formally evaluated until when we used large-eddy simulations (LESs) of airflow in and above forest canopies and presented the results in previous meetings. In this work, we focus on the evaluations of two second-order closure models and one third-order closure model. Given velocity moments from field experiments or LESs, it appears more straightforward to demonstrate differences in pressure-gradient interactions terms directly calculated from the LESs and those based on parameterizations in these existing higher-order closure models. Evaluating the impacts of such differences on the results produced by the higher-order closure models may be less straightforward because of the parameterizations of other terms (including turbulent length or time scales) and assumptions used in each model, as well as the potential compensating effects among the parameterizations of different terms in the budget equations. We will also examine the effects of canopy morphology (canopy height and vegetation density), vertical grid resolution, the depth of the roughness sublayer or the height of the inertial sublayer (upper boundary in these higher-order closure models).