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