Modeling flow patterns in a small vegetated area in the northern Chihuahuan Desert using QUIC (Quick Urban & Industrial Complex)

Sandstorms are frequent in the northern Chihuahuan Desert in New Mexico, an area characterized by open areas lacking vegetation, individual mesquite bushes, and mesquite coppice dunes. Field measurements of sand fluxes and wind velocities over a two year period provided a description of the area - suggesting that the "streets", the flat, elongated, non-vegetated areas aligned with the dominant wind directions are the principal sources of wind-dispersed soil and dust. However, since soil erosion and dust movement depend on the pattern, strength, and gradients in the wind field, modeling soil erosion and dust movement requires a continuous wind velocity field. Consequently, air flow patterns at this site were simulated using a semi-empirical mass-consistent diagnostic wind field model: QUIC version 3.5 (Quick Urban & Industrial Complex). Two hundred and fifty-one simulations were run encompassing several dust storms occurring in April 2003. Wind velocity vectors were compared between the model and field data at three heights for six locations and were found to correlate well for a majority of the situations suggesting that the flow patterns are consistent throughout the domain. In particular, good agreement was found for wind speeds at 0.75 m, the height for which the model was tuned. However, it overestimated velocities at 1.5 m (10%) and 3.15 m (13%). Generally, the model successfully identified locations of the highest wind velocities and wind stresses, predominately found in "streets" aligned with the driving wind, and locations of wake flow downwind of mesquite bushes where there was separation flow or otherwise shelter from the wind.