Air Quality Effects of Prescribed Fires Simulated with CMAQ
Yongqiang Liu, Gary Achtemeier, and Scott Goodrick
Forestry Sciences Laboratory, 320 Green St., Athens, GA
Third Annual CMAS Models-3 Conference Chapel Hill, October
18-20, 2004
Background
SHRMC-4S: A framework for smoke/air
quality simulation
Daysmoke: A model for fire plume rise
Case simulation of CMAQ with Daysmoke
Outline
Wildfire
Prescribed burning
Fire and Air Quality
Emission of smoke particles and gases
-PM, CO, SO2, NOx, VOC
Degradation of air quality
-PM2.5, smog, regional haze
SHRMC-4S(Southern High-Resolution Modeling Consortium-
Southern Smoke Simulation System)
A research tool for investigating air quality
effects of wildland fires, especially prescribed
burning in the South
Assisting fire and smoke managers and policy
makers in meeting air quality regulations and
developing implementation plans
Fire Data
Emissions Calculation
SMOKE
CMAQ
Visualization
Weather D
ata
EmissionsCalculation
Fuel Load
HourlyEmissions
Fire Behavior
FuelConsumption
EmissionFactors
PlumeParameters
Emissions Output(hourly Emissions, phase, area,
vertical velocity and dT)
Type Feature Stack Fire
Empirical Statistical correlation and regression
Holland 1953 Harrison and Hardy 2002
Similarity Similarity theory & dimensional analysis
Briggs 1968
Dynamic Conservations of mass, energy, and momentum
Briggs 1984 Daysmoke (Achtemeier 1998)
Plume Rise
Daysmoke as a Smoke Injector for CMAQ
Smoke plume riseVertical distribution
Daysmoke Components
Entraining turret plume model Detraining particle transport model Large eddy parameterization Vertical profile specification
Entraining turret model
The plume is assumed to be a succession of rising turrets.
The rate of rise of each turret depends on
•initial temperature
•initial vertical velocity
•effective diameter
•entrainment
Plume boundary
Plume boundary
The turrets sweep out a 3-D path that defines the plume boundary.
Particle movement within the plume is described by
• horizontal & vertical wind velocity within the plume,
• turbulent horizontal and vertical velocity within the plume,
• particle terminal velocity.
Detrainment occurs when
•Stochastic plume turbulence places particles beyond plume boundaries
•Plume rise rate falls below a threshold vertical velocity
•Absolute value of Large Eddy velocity exceeds plume rise rate
Large eddy parameterization
• Eddy size and strength are proportional to depth of PBL.
• Eddy growth and dissipation are time-dependent
• Eddies are transported by the mean wind in the PBL.
Constructing Vertical Plume Profiles
3 miles
“Wall” carries particle counters as function of height
Group the particles by CMAQ sigma level and insert into CMAQ each hour.
Running CMAQ with Daysmoke Plume Profiles
Florida March 6, 2002 12 km resolution 21 layers Plume rise is estimated using -Daysmoke -Briggs scheme
Vertical distribution of smoke particles estimated using Daysmoke. (Average over all fires in FL on 3/6/2002)
Normalized vertical distribution of smoke particles estimated using Daysmoke (pink) and Briggs scheme (green). (Average over all fires in FL on 3/6/2002)
CMAQ simulation of PM2.5 concentration with plume rise estimated using DAYSMOKE (top) and Briggs scheme (bottom) (σ=1.0; t=2pm; d=3/6/2002)
CMAQ simulation of PM2.5 concentration with plume rise estimated using DAYSMOKE (top) and Briggs scheme (bottom) (σ=0.91(~1000 m); t=2pm; d=3/6/2002)
CMAQ simulation of PM2.5 concentration with plume rise estimated using Daysmoke (pink) and Briggs scheme (green). (Average over the northwestern FL on 3/6/2002)
CMAQ simulation of O3 concentration with plume rise estimated using DAYSMOKE (top) and Briggs scheme (bottom) (σ=1.0; t=3pm; d=3/6/2002)
CMAQ simulation of O3 concentration with plume rise estimated using DAYSMOKE (top) and Briggs scheme (bottom) (σ=0.91; t=3pm; d=3/6/2002)
CMAQ simulation of O3 concentration with plume rise estimated using Daysmoke (pink) and Briggs scheme (green). (Average over the northwestern FL on 3/6/2002)
Concluding Remarks
CMAQ with DAYSMOKE would produce more particles near the ground
This study represents the first run with Daysmoke connected with CMAQ.
Daysmoke validation: – 3mm radar observations of prescribed burn plumes
scheduled for 2005 at Savannah River Forest– Comparisons with WRF simulations of smoke plumes– Matching with aerial photographs of smoke plumes