Validating the QUIC Dispersion Model in Sparse Canopy Settings: Particle Release Experiments in Vineyards

The QUIC (Quick Urban and Industrial Complex) Dispersion Modeling System is a building-resolving fluid simulation environment that uses empirical flow parameterizations constrained by mass conservation to create realistic flow fields and plume concentration fields with minimal computational expense. Typical QUIC domains are on the order of 1 kilometer with resolutions of ~0.5 m. Originally developed to predict the aerial spread of biological or chemical agents in cities, QUIC is now being modified for use as a decision aid by vineyard managers. At the project's completion, this tool will consist of a number of integrated models that collectively simulate wind fields, water vapor and CO2 exchange, heat transfer, plant growth, and dispersion of plant pathogens and pests for an entire growing season. The system is being designed with plant pathologists so that results from this modeling system will be able to inform management decisions involving pesticide application, airborne pathogen dispersion, and general canopy management.

Though QUIC's existing Lagrangian dispersion model (QUIC-PLUME) has been validated with data from field experiments mimicking urban settings, the present study is the first to validate it with field experiments performed in an agricultural setting with sparse canopies. The field data come from experiments carried out in 2011 and 2013 in a vineyard near Monmouth, Oregon. Fluorescent microbeads were released from a stationary point and collected with a 3D array of 100 impaction traps across 20 towers. Temperature, H2O flux, CO2 flux, and wind data were also collected. QUIC-PLUME output was compared with the field data using a variety of quality metrics (FAC2, FAC10, GME, and r^2). Discrepancies between field data and simulations are thought to be due in part to insufficiencies in the deposition model as well as QUIC's representation of a phenomenon known as channeling — the shunting of wind down rows of vines regardless of prevailing wind direction. Parameter optimization or implementation of alternative deposition models (based on work by Moran and Price) may increase the realism of the QUIC output.