Toward an integrated system for fire, smoke and air quality simulations

Abstract

In this study, we describe how WRF-Sfire is coupled with WRF-Chem to construct WRFSC, an integrated forecast system for wildfire and smoke prediction. The integrated forecast system has the advantage of not requiring a simple plume-rise model and assumptions about the size and heat release from the fire in order to determine fire emissions into the atmosphere. With WRF-Sfire, wildfire spread, plume and plume-top heights are predicted directly, at every WRF time-step, providing comprehensive meteorology and fire emissions to the chemical transport model WRF-Chem.Evaluation of WRFSC was based on comparisons between available observations to the results of two WRFSC simulations.The study found overall good agreement between forecasted and observed fire spread and smoke transport for the Witch-Guejito fire. Also the simulated PM2.5 (fine particulate matter) peak concentrations matched the observations. However, the NO and ozone levels were underestimated in the simulations and the peak concentrations were mistimed. Determining the terminal or plume-top height is one of the most important aspects of simulating wildfire plume transport, and the study found overall good agreement between simulated and observed plume-top heights, with some (10% or less) underestimation by the simulations. One of the most promising results of the study was the agreement between passive-tracer modeled plumetop heights for the Barker Canyon fire simulation and observations. This simulation took only 13h, with the first 24h forecast ready in almost 3h, making it a possible operational tool for providing emission profiles for external chemical transport models.

Modeling Wildfire Smoke Feedback Mechanisms Using a Coupled Fire‐Atmosphere Model With a Radiatively Active Aerosol Scheme

“…The WRF-SFIRE-CHEM modeling framework (WRFSC), which couples a fire-atmosphere model with a chemical transport model (WRF-CHEM; Grell & Baklanov, 2011), was used to simulate smoke-induced inversions observed across Northern California on 19-20 August 2015. The integration of the atmospheric, fire, and chemical transport models enables WRFSC to explicitly simulate the fire propagation, plume rise, and smoke dispersion and chemistry (Kochanski et al, 2016). For the purpose of this study, WRFSC's integration with the RADM2 (Stockwell et al, 1990) and MOZART (Emmons et al, 2010) chemical mechanisms was extended to the Goddard Chemistry Aerosol Radiation and Transport (GOCART) scheme (Chin et al, 2000).…”

Wildfire and Weather Radar: A Review

“…Various approaches have been taken to the coupled modeling of wildfires with the atmosphere. However, this research is hindered by the lack of data to validate pyrogenic processes and deep pyroconvection on the scale at which they occur (Coen et al, 2013;Coen & Schroeder, 2015;Kochanski et al, 2013Kochanski et al, , 2016Peace et al, 2015). Data sets on fire behavior and spread (e.g., isochrones and heat release rate) are also scarce from large events, as most data are collected from smaller experimental fires (Achtemeier, 2013;Filippi et al, 2013;Kochanski et al, 2012;Peterson et al, 2017).…”

Modeling Study of the Air Quality Impact of Record‐Breaking Southern California Wildfires in December 2017

“…There have been numerous modeling studies investigating the impact of wildfires on the air quality over different scales (Herron-Thorpe et al, 2014;Reid et al, 2016). However, only a few studies (Kochanski et al, 2016;Pfister et al, 2008) have specifically simulated the air quality consequences of Santa Ana wind-driven fires, the most costly and dangerous fire regime over Southern California. For example, using a global chemical transport model and surface O 3 observations, Pfister et al (2008) found that fire emissions enhanced afternoon 8-hr O 3 concentrations by about 10 ppb during a fall 2007 California wildfire event.…”