Yongqiang Liu, Gary L. Achtemeier, and Scott L. Goodrick

Center for Forest Disturbance ScienceUSFS Forestry Sciences Laboratory

Athens, GA 30602, USA

Sensitivity of CMAQ Simulations to Prescribed Burn Emissions under Varied Plume Core Numbers

OutlineOutline

Multiple cores of smoke plumes:

A feature of Daysmoke

Sensitivity analysis of Daysmoke

Impacts on CMAQ simulations:

Brush Creek burn

Summary and Conclusions

Emissions from Forest Fire

•Elevated emission source

•Plume rise and vertical profile are needed for air quality models

Point vs Area Source

Air quality effects in burn areas are reduced as point source

Air quality effects in burn areas are reduced as point source

Area

Point

Simulation with VISTAS Data (Fire as an Area Source)

Over-prediction of ground concentrations at most sites(from Wang et al.)

March 2002

DaysmokeDaysmoke

Developed from an ash dispersion and deposition

model for sugar cane burn (Achtemeier 1998)

A smoke particle transport and dispersion model

A smoke injection scheme for air quality models

DaysmokeDaysmoke

SMOKE

CMAQ

DAYSMOKE

A unique feature with SHRMC-4S is coupling of Daysmoke.

A smoke particle transport and dispersion model

A fire plume rise scheme for air quality models

Time-height cross section of PM2.5 concentration (μg m-3)

Emission as area source

Emission as point source with Daysmoke

A Problem with CMAQ-Daysmoke Simulation of Fire Emissions

Multiple-core Updraft of Smoke Plume: A Possible Solution?

Research Issues on MultipleResearch Issues on Multiple--core Updraftcore Updraft

Description of multiple-core plumes in Daysmoke

Importance relative to other properties

Impacts on Daysmoke simulation

Gary Achtemeier et al.

Impacts on CMAQ-Daysmoke simulation

This presentation

Processes Processes

Particles dropping out of plume

Particles moving up with plume

Plume deformationdue to turbulent

fluctuation Plume rise

Vertical profile

Components of Components of DaysmokeDaysmoke

FactorFactorMajor Major ProcessProcess

FunctionFunctionModelModel

U, hU, hConvectionConvectionEstimate Estimate uu’’LEDLEDLEPLEP

Fuel and burn Fuel and burn propertiesproperties

CONSUMECONSUMEEPMEPM

Emissions, Emissions, initial values, initial values, plume riseplume rise

REMREM

U, U, uu’’turbturb, , uu’’LEDLED

RR00 ((DD), w), w00, , ΔΔTT00

MomentumMomentum

BuoyancyBuoyancy

Displacement Displacement of particlesof particles

BoundariesBoundaries

DPMDPM

ETMETM

Description of Daysmoke

Comparison with Briggs scheme

Plume risePlume riseStatic Static similarity similarity relationship relationship

StackStackBriggsBriggs

Plume risePlume riseProfileProfile

Feature Feature ProvidedProvided

3D dynamic3D dynamic--stochasticstochastic

Model TypeModel Type

FireFire

EmissionEmissionSourceSource

DaysmokeDaysmoke

SchemeScheme

Description of Multiple Cores in Description of Multiple Cores in DaysmokeDaysmoke

D = [ 4 F / ( c D = [ 4 F / ( c ππ n ) ]n ) ]1/31/3

D D —— effective plume diametereffective plume diametern n —— the number of coresthe number of coresF F —— volume fluxvolume fluxc c —— coefficientcoefficient

The larger n, the smaller D, The larger n, the smaller D, the lower plume risethe lower plume rise

DaysmokeDaysmoke Parameters Parameters Parameter Meaning Parameter Meaning RangeRange

Cp Plume turbulence coefficient Cp Plume turbulence coefficient 0.050.05--0.20.2Cu Air horizontal turbulence coefficient Cu Air horizontal turbulence coefficient 0.050.05--0.20.2CwCw Air vertical turbulence coefficient Air vertical turbulence coefficient 0.010.01--0.080.08KxKx Thermal horizontal mixing rate Thermal horizontal mixing rate 0.50.5--1.51.5KzKz Thermal vertical mixing rate Thermal vertical mixing rate 0.50.5--1.51.5WcWc PlumePlume--toto--environ. cutoff velocity 0.1environ. cutoff velocity 0.1--0.50.5w* Air induced ash downdraft velocity w* Air induced ash downdraft velocity 0.00.0--0.010.01WrWr Maximum rotor velocity Maximum rotor velocity 0.250.25--0.750.75PkPk Entrainment coefficient for plume Entrainment coefficient for plume 0.050.05--0.250.25W1 Initial plume vertical velocity W1 Initial plume vertical velocity 1.01.0--3.03.0TD Initial plume temperature anomaly TD Initial plume temperature anomaly 2.02.0--8.08.0FdFd Diameter of flaming area Diameter of flaming area 2.52.5--100.0100.0Tm Surface temperature Tm Surface temperature 75.075.0--85.085.0Dm DewDm Dew--point temperature 60.0point temperature 60.0--80.080.0Wm Surface wind Wm Surface wind 1.01.0--5.05.0

Sensitivity ExperimentSensitivity Experiment

Fourier Amplitude Sensitivity Test (FAST): identify which parameters mostly affect the plume rise in Daysmoke.

Conditions: The input parameters, assumed to be mutually independent, are varied simultaneously through their ranges of possible values.

Method: Partial variance of model output measures the uncertainty due to the variability of the input parameters.

Advantage: 1027 runs for a model with 15 input parameters (1015

with a sampling technique for 10 values within the range of all input parameters)

Most Important PropertiesMost Important Properties

0

10

20

30

40

50

cp cu cw kx kz wc w* wr pk w1 TD fd tm dm wm

Parameter

Par

tial V

aria

nce

(%) Contribution of

core numberMixing Height

Fire Data

Emissions Calculation

SMOKE

CMAQ

Visualization

Weather Data(MM5)

How to Affect Air Quality Simulation

SHRMC-4S (Southern High-Resolution Modeling Consortium-Southern Smoke Simulation System)

CMAQ: a core component of SHRMC-4S

Examine Impacts with Examine Impacts with Brush CreekBrush Creek Burn CaseBurn Case

LocationBrush Creek unit of the Cherokee National Forest (near Tennessee -North Carolina border)

Date: March 18, 2006

Burned area: 1656 acres

CMAQ SimulationCMAQ Simulation

Resolution: 12 km

Vertical layer: 21

Meteorology: MM5

Emission: Consume and EPM

Chemical Mechanism: Carbon Bond-IV

Asheville, North Carolina PM2.5 Concentrations

0

20

40

60

80

100

120

140

0 4 8 12 16 20 0 4 8 12 16 20 0 4 8 12 16 20 0 4 8 12 16 20 0 4 8 12 16 20

Date and Hour

Con

cent

ratio

n (u

g/m

3)

PM2.5

Unhealthy for sensitive groups

Good

Moderate

3/16/2006 3/17/2006 3/18/2006 3/19/2006 3/20/2006

Satellite remote sensed smoke plume

~ 1700 LST

Side View of the Brush Creek Burn

(a) (b)

Plume Rise and Vertical Profile

PBL

Plume rise

Single-core updraft 10 - core updraft

PM2.5 Concentration at Burn SitePM2.5 Concentration at Burn Sitefrom from DaysmokeDaysmoke

1-core 10-core

Downwind PM2.5 ConcentrationDownwind PM2.5 Concentration

1-core 10-core

Simulated Plume (12-km resolution)

1500 1600

1700 1800

Asheville

Red = 20 ug/m3

1500

1700

1600

1800

Red= 40 ug/m3

ConclusionConclusionThe number of plume cores is an important factor. The number of plume cores is an important factor.

The problem is how to define the correct plume core The problem is how to define the correct plume core numbers for CMAQnumbers for CMAQ--DaysmokeDaysmoke simulations. simulations.

SummarySummaryA new smoke plume feature of multipleA new smoke plume feature of multiple--core core updraft is added in updraft is added in DaysmokeDaysmokeUnlike singleUnlike single--core updraft, core updraft, DaysmokeDaysmoke ejects a ejects a large part of smoke particles within PBL for large part of smoke particles within PBL for multiplemultiple--core updraft.core updraft.Core number is most important factor for Core number is most important factor for

determining plume heightdetermining plume heightCMAQCMAQ--DaysmokeDaysmoke obtains a much larger ground obtains a much larger ground PMPM2.52.5 concentration for multipleconcentration for multiple--core than singlecore than single--core updraft, which is closer to the measurements.core updraft, which is closer to the measurements.

AcknowledgementAcknowledgement

Supports from the National Fire Plan, USDA Supports from the National Fire Plan, USDA Cooperative State Research, Education, and Cooperative State Research, Education, and Extension Service (CSREES) Air Quality Program Extension Service (CSREES) Air Quality Program and EPA.and EPA.Burn information from Florida Division of Forestry.Burn information from Florida Division of Forestry.Satellite images from William Jackson of Cherokee Satellite images from William Jackson of Cherokee National Forest. National Forest.

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