Evaluation and development of a high resolution wind model for wildfire applications in complex terrain.

摘要

Accurate modeling of near-surface winds is important for wildfire applications, including wildfire behavior and spread as well as post-fire processes, including wind-driven dust and ash emissions from burned soils. The work presented in this dissertation investigates a high resolution wind model for use in wildfire applications in complex terrain and includes (1) an observational field study to collect high resolution surface wind data from two types of complex terrain features; (2) use of these observed data to evaluate a suite of Numerical Weather Prediction (NWP) model near surface wind predictions and dynamical downscaling of those predictions with a high resolution wind model; and (3) field quantification of wind erosion from soils burned by wildfire. Unique flow features, including upslope, downslope, and synoptically-driven flow events were presented for an isolated mountain and a steep river canyon. Evaluations with these observed datasets indicated that NWP surface winds can be improved in complex terrain via dynamic downscaling with a high resolution wind model, WindNinja, so long as the average approach flow to the area of interest can be reasonably defined (i.e., the initial wind field must be appropriately defined). The biggest improvements occurred during periods of synoptically-driven events when observed winds speeds exceeded 10 m s-1. Results from the post-fire field campaign demonstrated that post-fire landscapes can be significant sources of particulates and that dust emissions can persist for up to a year post-fire. Data collected during this study represents the first real-time measurements of PM10 fluxes from a burned landscape. These data will be useful in evaluating windblown dust emissions algorithms applied to burned landscapes.