AIRBORNE MONITORING AND SMOKECHARACTERIZATION OF PRESCRIBED FIRES

ON FOREST LANDS IN WESTERN WASHINGTONAND OREGONFINAL REPORT---Eo---LOCKHEED-EMSCO

PROJECT NUMBERS AM526 AND AM680

Lawrence F. Radke, Jamie H. Lyons,Dean A. Hegg and Peter V. Hobbs

Apri 1983

(corrected version)

TABLE OF CONTENTS

1. INTRODUCTION

2. AIRCRAFT INSTRUMENTATION

2.1 Overview2.2 Particle Measuring System2.3 Trace Gas Measuring System2.4 General Meteorological Instrumentation2.5 Data Processing System

3. SUMMARY OF RESEARCH FLIGHTS

4. INSTRUMENT CALIBRATION AND QUALITY CONTROL

4.1 Di scussion of Interim Cal ibration PerformedIn-house (19 July 1982)

4.2 Research Triangle Institute Fi el d Audit4.3 Comparison of Pl ume-Ambient CO^ Concentrations

as Measured by OGU and Lockheed-EMSCO

5. FLIGHT PROCEDURES AND DATA PROCESSING

5.1 Fl ight Procedures5.2 Data Processing5.3 Physical Interpretation of b^at Al gorithms

6. PRELIMINARY RESULTS AND ANALYSIS

6.1 Characterization of Cross Sections of the Plumes6.2 Some Characteri sti cs of the Particles in the Plumes6.3 Analysis and Cross Comparisons of Bul k Ai r Samples6.4 Plume Tracers6.5 Emission Factors for Total Suspended Particulates (TSP)6.6 Aerosol Mass Fl ux

7. TOPICS FOR FURTHER STDY

8. SUMMARY AND CONCLUSIONS

REFERENCES

APPENDIX I Corrected Data Sets (Mi ssions 1-6)

APPENDIX II Sampl e Information Table (Missions 1-6)

LIST OF TABLES AND FIGURES

TABLE

2 1 Speci fications of research instruments aboard theUniversity of Washington’s B-23 ai rcraft

3.1 Summary of research fl ights

4.1 Summary of audit of instrumentation

4 2 Comparison of OGC and Lockheed-EMSCO measurements of plumeminus ambient C02 concentrations col lected in stainless steelcanisters via the polyethylene bag

4 3 Compari son of OGC and Lockheed-EMSCO measurements of pl umeminus ambient C02 concentrations col lected in stainless steelcanisters via the stainless steel loop with those col lected

in stainless steel canisters via the polyethyl ene bag

5. 1 Al gorithms relating b ^to mass concentration

6.1 Compilation of ai r volume flux and its associated valueof light-scattering coeffi cient (bgcat)

6.2 Apparent density of particles in pl ume

6.3 PIXE analyses of the emissions from the sl ash burns

6 4 Comparison of Oregon Graduate Center and Lockheed-EMSCOmeasurements on ai r samples col lected in canisters fromthe polyethyl ene bag sampler

6 5 Comparison of Oregon Graduate Center measurements onsampl es col lected in canisters from the stainless steelsampl ing loop with the Lockheed-EMSCO measurements onsampl es col lected in canisters from the polyethyl ene bagsampler

6.6 Emission factors for TSP derived by carbon bal ance methodusing weighed fi lters

6. 7 Comparison of emission factors for particle mass usingthe carbon balance method and various techniques formeasuring particle mass concentration

6.8 Correlation coefficients for TSP emission factorsfrom data in Table 6.7

6.9 Particle mass fluxes in pl umes calculated from fi lters,mass monitor and particle size measurements

A.I The corrected data set used in cal cul ation of emissionfactors for Total Suspended Parti cul ate (TSP) derivedby the carbon balance method.

A.2 Sample Information Table. Mi ssions 1-6

FIGURE

2 1 Aerosol and trace gas instrumentation aboard theUniversity of Washington’ s B-23 ai rcraft

2 2 Measurement ranges of the particle sizing instrumentsaboard the University of Washington’ s B-23 ai rcraft

2.3 The batch ai r sampler aboard the University ofWashington’ s B-23 ai rcraft

2.4 Fl ow chart for aircraft instrumentation tape to a7-track computer tape and voice transcripts

2.5 Flow chart for conversion of 7-track computer tapes andfl oppy di sks to 9-track tapes and prel imi nary analysishard copies

2.6 Fl ow chart for processing 9-track tapes into finalhard copy printouts and graphics

5. 1 A plot of the weighed fi lter mass concentration versus

^scat ^or the 0^9" data set

5.2 A plot of the weighed fi lter mass concentration versus^scat ^or t1ne Washington data set

5.3 A pl ot of the mass monitor mass concentration versus

^cat for the Q^0" data set

5.4 A plot of the mass monitor mass concentration versusbgcat for the Washington data set

6.1 Vertical cross section of the light-scatteringcoefficient of the plume from the 23 July 1982burn, sequence 1

6.2 Vertical cross section of the light-scatteri ngcoefficient of the pl ume from the 23 July 1982burn, sequence 2

6.3 Vertical cross section of the light-scatteringcoefficient of the pl ume from the 23 July 1982burn, sequence 3

6.4 Vertical cross section of the light-scatteringcoefficient of the plume from the 23 July 1982burn, sequence 4

6.5 Vertical cross section of the light-scatteringcoefficient of the plume from the 25 July 1982burn, sequence 2

6.6 Vertical cross section of the light-scatteringcoefficient of the pl ume from the 26 July 1982burn, sequence 5

FIGURE PAGE

6 7 Verti cal cross section of the light-scattering 51coeffi cient of the pl ume from the 15 September 1982burn, sequence 4

6.8 Vertical cross section of the light-scatteri ng 52coefficient of the plume from the 23 September 1982burn, sequence 3

6.9 Particle size distribution measured 3.3 km downwind 58of burn on 23 July 1982

6.10 Number concentration versus size of particles measured 60near pl ume center on the 23 July 1982

6.11 Shadow images of airborne particles in plume on 6215 September 1982

6.12 Number concentration versus size of particles measured 64with laser camera near the center of the pl ume on15 September 1982

6.13 Number concentration versus size of particles measured 65with aerosol system near the center of the plume on15 September 1982

6.14 Characteristi cs of the particles near the center of the 67pl ume as a function of time after ignition on 23 July1982

6.15 Characteristics of the particles near the center of the 68plume as a function of time after ignition on25 July 1982

6.16 Characteristics of the particles near the center of 69the pl ume as a function of time after ignition on26 July 1982

6. 17 Characteristics of the particles near the center of 70the plume as a function of time after ignition on15 September 1982

6.18 Characteristics of the particles near the center of 72the pl ume as a function of time after ignition on23 September 1982

6.19 Volume concentration versus size of particles measured 76near plume center on 25 July 1982 and 23 September 1982

6.20 Emission factors for Total Suspended Particul ate (TSP) 89as a function of time after ignition for Oregon burns

^ on 23 July, 24 July and 26 July 19826.21 Emission factors for Total Suspended Particul ate (TSP) 90

as a function of time after ignition for Washington burnson 15 September and 23 September 1982

v

Particle mass fl uxes derived from particle massmeasurements

AIRBORNE MONITORING AND SMOKE CHARACTERIZATION OF PRESCRIBED FIRES

ON FOREST LANDS IN WESTERN WASHINGTON AND OREGON

1. INTRODUCTION

The combination of wi ld forest fi res prescribed burning of forest logging

wastes and agricultural burning, constitutes one of the largest sources of

di rectly injected particles into the atmosphere (SCEP, 1970). In a recent

report from the Southern Forest Fi re Laboratory (Ward et a1 1976) it was noted

that about 10 hectares of forest land are burned annual ly in the United States

but that estimates of the quantity of particles emitted into the atmosphere from

this source range from 0.5 to 50 mi ll ion metri c tons per year. The Envi ronmental

Protection Agency has estimated the total di rect emission of particulate from al

sources in the United States to be 20 mi ll ions metric tons per year (SCEP, 1970).

Cl early, the upper limit for estimates of particles from the burns of forest land

s inconsi stent with the EPA estimate for total emissions. The uncertainties are

due to the limited data base and al so to the di ffi culty of obtaining good

measurements of particle emission rates from large areal sources such as forest

fi res.

The present study is concerned with an effort to characterize particle

emissions from the prescribed burning of forest biomass (harvesting residues) as

functions of time, combustion character, fuels, and forestry practices. The

studies invol ved detai led ai rborne measurements of the pl umes from seven

prescribed burns in Washington and Oregon. Five of these tests were designed to

ncrease knowl edge of the effects of residue removal to various size

speci fications, on emissions (one of the major problem areas being researched by

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the USOA Forest Service, Forest Residues and Energy Program, Paci fic Northwest

Forest and Range Experiment Station. The other two tests were conducted to

examine "mass ignition" techniques (such as helitorch) as an emissions-reduction

method. It was hypothesized by the Forest Service that rapid ignition of areas

of timber harvest residues may be one way of reducing the composite emissions

factor and of limiting the period of smoldering combustion. The combined data

set suppl ements work completed duri ng 1981, in which two prescribed fi res were

sampled by another contractor. Results of this earl ier work have been reported

by Anderson et a1 (1982) Ward and Sandberg (1982) and Sandberg and Ward

(1982).

The University of Washington’ s (UW) role in this study was to obtain air-

borne measurements of the emissions from prescribed burns. The prel iminary

resul ts of this study which are reported here, are confined to the ai rborne

data col lected by the UW together with some di scussion of sampl es col lected by

the UW but analyzed by Lockheed Engineering and Management Services (Lockheed-EMSCO)

the Oregon Graduate Center (OGC) and the Crocker Laboratory of the University of

Cal fornia at Davis.

In this report we wi characterize the fi res with respect to pl ume

dimensions, particle size distributions, particle densities and particle

emission fluxes. In order that our analysis of the emissions be as independent

as possible, this prel iminary report was prepared without detai led information

on ignition techniques, "yarding" preparation, fuel moisture and other surface

measurements related to the prescribed burns. A report relating emissions to

ignition techniques and other factors wi be prepared at a later date.

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In addition to the emissions characterizations discussed in this report.

a large number of other types of data were col lected by a number of cooperators

working under the leadership of the USOA Forest Service, Pacific Northwest Forest

and Range Experiment Station. The overal data col lection, data reduction and

analysis is being coordinated by David V. Sandberg and Darold E. Ward of the

Forest Service (see Ward and Sandberg, 1982. The study was cooperatively funded

and administered by the U.S. Forest Service; the Envi ronmental Protection Agency

(EPA) Region X; the Department of Energy, Region X, through Bonnevil le Power

Administration; and the EPA Envi ronmental Monitoring Systems Laboratory of Las

Vegas Nevada.

2. AIRCRAFT INSTRUMENTATION SYSTEM2.1 Overview

The ai rcraft used in this study was the DM B-23, which is maintained and

operated by the Cl oud and Aerosol Research Group of the Atmospheric Sciences

Department at the UW.

The trace gas and aerosol instrumentation aboard the ai rcraft is shown in

Fi g. 2. 1 and descriptions of the instruments are given in Table 2.1. The pri-

mary measurements of interest in this study were concentrations of ozone and

particle size di stributions. Measurements of total suspended particulates (TSP)

using weighed fi lters were augmented by a mi crobalance cascade impactor (with a

di ffusion drier) and a mass monitor (with a 2 pm diameter cutoff inlet impactor

and diffusion drier)

The overal performance of the compl ete measuring system was excel lent

during the several experiments.

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ASASP-X

BATCH SAMPLER

^-INTEGRATING NEPMELOMETERISOKINETICPROBE

STATICPRESSURETRANSDUCER

30L HEATEDCHAMBER

\ C

SEAT SEAT SEAT

^ISOKINETICPUMP

1 FB(

STAINLESS STEEL-HYDROCARBON SAMPLE

INTEGRATINGNEPHELOMETER- /-AX ALLY

^ SCATTERINGSPECTROMETERPROBE

HEATEDPLENUMCHAMBER

^ HYDROCARBON ’-CLOUD< STAINLESS STEEL WATERIDFTAI CAUDIMETAL BELLOWSSAMPLE PUMP SAMPLER-WAND FORIMPACTIONSAMPLING

ROYCO 245SAMPLE HEAD

Figure 2. 1 Aerosol and trace gas instrumentation aboard the University ofWashington’ s B-23 research aircraft. Meteorological navigational cloud andprecipitation instrumentation are not shown.

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TABLE 2.1 SPECIFICATIONS OF RESEARCH INSTRUMENTS ABOARDTHE UNIVERSITY OF WASHINGTON ’S B-23 AIRCRAFT

Parameter

Total ai rtemperature1’

Static airtemperature

Dew point

Pressureal titude1"

True ai rspeed1’

Ai r turbul ence1’

Liquid watercontent^

Electric field^

Instrument type

Platinum wi reresistance

Computer value

Dew condensation

Variablecapacitance

Variablecapacitance

Di fferential

Hot wi re resistance

Rotary field mil

Manufacturer

Rosemount Model102CY2CG + 414 LBridge

In-house

Cambridge SystemsModel TH73-244

RosemountModel 830 BA

RosemountModel 831 BA

MeteorologyResearch, Inc.Model 1120

Johnson-Wi iams

MeteorologyResearch, Inc.Model 611

Range (and error)*

-70 to 30C(< 0. 1 C)

-70 to 30C(< 0.5C)

-40 to 50CC)

150 to 1060 mb(< 0.2%)

0 to 230 m s-1(< 0.2%)

0 to 10 cm2/3 s-1(< 10%)

0 to 2 g m-30 to 6 g m"3

0 to 110 kV(< 10%)

Types and sizesof hydro-meteors1’

Ice particleconcentrations1’

Metal foi impactor

Optical polarizationtechnique

MeteorologyResearch, Inc.

Model 1220A

In-house

Detects particles(> 250um)

0 to 1000 &-1detects particles(> 50um)

* Al particle sizes refer to maximum particle dimensions.+ Data displ ayed or avai lable aboard the ai rcraft.++ Not relevant to this study.

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TABLE 2. 1 (CONTINUED

Parameter Instrument type Manufacturer Range (and error)^

Concentration ofcloud condensa-tion nucleus...spectrometer

Ice nucleusconcentrations^ t^

Ice nucleusconcentrations TT

Concentrations ofsodium-containingparti cles’*" "^Al titude aboveterrain1’

Weather radar1’

Ai rcraftposition andcourse pl otter1’

Time^

Time T

Ground communi-cation1’

Light-scatteringcoefficient1’

Four verticalthermal diffusionchambers

NCAR acousticalcounter

Polarizing

Fl ame spectrometer

Radar altimeter

5 cm gyro-stabi ized

Works off DMEand VOR

Time code generator

Radio WWV

FM transceiver

Integrating nephelo-meter

In-house

In-house

Mee Industries

In-house

AN/APN22

Radio Corp. ofAmerica AVQ-10

In-house

Systron DonnerModel 8220

Gertsch RHF 1

Motorola

Meteorology Res.Inc. Model 1567(modified forincreased stabil ityand better responsetime)

0 to 5000 cm-3(< 10%)Simultaneous measure-ments at 0.2, 0.5, 1.0,1.5% supersaturation

0.01 to 500 &-1

0.1 to 10,000 A-1

0 to 10,000 fc-11%)

0 to 6 km5%)

100 km

180 km(1 km)

h, min, s(1: 105)

min

200 km

0 to 1.0 x 10-4 m-1or

0 to 2.5 x 10-3 m-1

* Al particle sizes refer to maximum particle dimensions.!’Data displ ayed or avai lable aboard the ai rcraft.+t Not relevant to this study.

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TABLE 2.1 (CONTINUED)

Parameter

Heading1’

Ground speed anddri ft angle1’

Ul travioletradiation1’

Angle of attack1’

Photographs1’

Total gaseoussul fur

Ozone t"

NH3, NO. N02, N0^Si ze spectrum ofaerosol particles1’

Si ze spectrum ofaerosol parti cles1’

Si ze spectrum ofaerosol particles

Si ze spectrumof aerosolparticles

Si ze spectrumof aerosolparticles!

Instrument type

Gyrocompass

Doppler navigator

Barrier-layerphotoelectric cel

Potentiometer

35mm time-lapsecamera

FPD flamephotometric detector

Chemi umi nescence(C2H4)

Chemi luminescence(03)

Electric aerosolanalyzer

90 ight-scattering

Forwardight-scattering

Di ffusion battery

35-120 light-scattering

Manufacturer

Sperry Model C-2

Bendi x ModelDRA-12

Eppley Laboratory,Inc. Model 14042

RosemountModel 861

AutomaxModel GS-2D-111

Mel oy Model 285

Monitor LabsModel 8410 A

Monitor LabsModel 8440

Thermal Systems,Inc. Model 3030

Particle MeasuringSystem (LAS-200)

Royco 245(in-house modi fied)

Thermal SystemsInc. Model 3040with in-houseautomatic valves &sequencing

Particle MeasuringSystems, ModelASASP-X

Range (and error)*

0 to 3602%)

0 to 6 km altitude

0.7 J m-2 s-1(< 5%)

+/- 23(< 0.5)

s to 10 mi n

0.5 ppb ppm

0 to 5 ppm(< 7 ppb)

0 to 5 ppm10 Ppb)

0.0032 to 1.0 urn

0.5 to 11 urn

1.5 to 40 urn

0.01 0.2 urn

0.09 3.0 urn(

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TABLE 2. 1 (CONTINUED)

Parameter

Size spectrumaerosol andcloud particles!"

Size spectrumcloud parti cles

Si ze spectrum ofprecipitationparticles’*"

Images ofcl oud particles

Images ofprecipitationparticles^

Instrument type

Forward light-scattering

Diodeocculation

Diodeoccul tation

Diode occulationimaging

Diodeimaging

Manu1

ParticleSystems,FSSP

ParticleSystems,OAP-200X

ParticleSystems,OAP-200Y

ParticleSystems,OAP-2D-C

ParticleSystems,OAP-2D-P

’acturer

MeasuringModel

MeasuringModel

MeasuringModel

MeasuringModel

MeasuringModel

Range (and error)*

2 to 47 urn

20 to 300 urn

300 to 4500 pm

Resolution25 urn

Resolution200 urn

Concentrationsof Aitken nucl ei^

Concentrationsof Ai tken nuclei’*’

Si zes and typesof aerosolparticles f

Concentrations ofce nuclei^"*"

Mass concentrationaerosol particles1’

Particulate sul fur

SO^. NOg", C1 ",Na^ K^ NH^

++

Light transmission

Rapid expansion

Di rect impact ion

Di rect impact ion

Electrostatic depo-sition onto matchedoscil lators

Tefl on fi ltersCSI & Dionex XRFspectroscopy andion exchangechromatography

General El ectri cModel CNC II

Gardner

Glass sl ides

Nuclepore/Mi Hi port

Thermal Systems,Inc. Model 3205

In-house

102 to 106 cm-3(particles >0.005 urn)

2 x 102 to 107 cm

5 to 100 ym

0.1 to 3000 yg m"3(< 0.1 ug m-3)

0. 1 to 50 urn m"3(for 500 literair sample)

* A1 particle sizes refer to maximum particle dimensions.+ Data displayed or available aboard the aircraft.++ Not relevant to this study.

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TABLE 2. 1 (CONTINUED)

Parameter

Cl oud watersamples

Instrument type

Centri fuge

Manufacturer

In-house

Range

Col lectsdropletswith an> 50%.

*(and error)

cloud> 3 um radius

efficiency

Si ze-segragated-’concentrations ofaerosol particles

Cascade impactiononto matchedoscil lators

Cal iforniaInstruments

0.05-25 um

Size-segregatedconcentrationsof aerosolparticles

++ Cascade impactor Sierra InstrumentsInc.

0. 1 3 urn(6 size fractions)

HNO. ++

Hydrocarbons

CO^

co^Total suspendedparti cul ate

t+

Nylon fi lters withteflon pre-fi lterfol lowed by ionchromatography

Gas chromatograph(flame ionizationdetection)

El ectrochemicaloxidation

IR absorption

Hi gh volumesampler

Dionex

Analytical InstrumentDevelopment Inc.Model 511

EcoloyzerModel 2000

Foxboro Mi ran IA

Nucleom’c Corp.Model HA69

Variable

0.5(as

100 ppmCHJ

0.100 and 0.600 ppm

3 2x10 ppm

Total suspendedparticulate (TSP)

25 mm Teflon filter Analysis to be(electrobalance provided byanalysis) Lockheed-EMSCO

* Al particle sizes refer to maximum particle dimensions.+ Data displ ayed or avai lable aboard the ai rcraft.++ Not relevant to this study.

Suppl ied by EPA/Lockheed-EMSCO.

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2.2 Particle Measuring System

The particle light-scattering coefficient of ai r is measured with an

in-nouse modi fied, MRI 1567 integrating nephelometer, which samples from a 30

iter plenum chamber maintained at 5C above ambient temperatures. Outside

ambient air is introduced into this chamber isokinetical ly by means of a pump

connected to a static pressure transducer that maintains zero overpressure in

the head and line of the sample probe to the plenum chamber. The above ambient

temperature of the plenum chamber ensures that only dry particles enter the

*ntegrating nephelometer.

The main fi lter sampl ing system consists of a ~500 iter polyethyl ene bag

whi ch is fil led nearly isokinetical ly by ram ai r through a 2 1/2" diameter

sampl e port, a fi lter sampl ing mani fold with fl owmeter, and an engine-driven

vacuum pump. The bag takes ~5 s to fi and entrains al parti cles 5 urn is not

quanti fied) After the bag is fi led, a sample of the ai r in the bag is pul led

through a 37 mm diameter Teflon filter. Sample fl ow rates and mass flow volumes

are measured by a TSI 2013B mass fl ow sensor interfaced with a microprocessor.

Post-fl ight analysi s of the fi lters was done at the Crocker Laboratory. The

results of these analyses are discussed in this report.

A major sub-unit of the UW particle measurement system is concerned with

measurements of the size spectra of the atmosphere aerosol Because the par-

ticles span a size range of nearly four decades in diameter, several di fferent

sensors must be employed. Thi s is il lustrated in Fig. 2.2 where a typical

* Ai r from the plenum chamber was automatical ly passed through fi lters when theight-scattering coefficient indi cated that the ai rcraft was in the plume

from a burn. These filters were sent for analysis to the Crocker Laboratory,University of Cal fornia, Davis.

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volume di stribution for a power pl ant plume is shown togetherwith the various

instruments that we employ to measure the sizes of the particlesin the

di stribution. These instruments (to be described below) have widely varying

response and analysis times. This variabil ity requi res that they al sample

from a common batch sample of ai r in order to obtain comparablemeasurements.

A batch sample is also necessary if sharp concentration gradientsof particles

exist in the ai r, such as the smoke pl umes described herein.The batch sampler

employed on the B-23 ai rcraft consists of a -90 iter cyl inder (-150 on in

height) with a freely-floating piston capping the sample. Ai r pressureforces

the piston upwards, fi ing the cyl inder with ambient ai r.Because the sample

offers negl igible resistence to the in-coming ai r, sampl ing is essentially

isokinetic. After fil ing, the various particle-sizing instruments samplefrom

the base of the cyl inder (to avoid sedimentation loss) A schematic of this

batch sampler is shown in Fig. 2.3. A brief description of the various

particle-size measuring instruments fol lows.

The smal lest particles measured are sized by means of an electrical aerosol

analyzer (EAA) and a di ffusion battery coupled to an Aitken nucleus counter.

The EAA operation is based on the relationship between a parti cle’ s charge,

size and electrical mobil ity. Particles entering the instrument are charged,

thei r mobi ities in an electrical field are measured, and thei r sizes are

thereby deduced. The diffusion battery measures particle sizes by determining

the number of fine-mesh screens through which the particles can di ffuse. The

greater the screen "penetration", the larger the size of the particles.

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AIR INLET

Figure 2. 3 The batch air sampler aboard the UW B-23 ai rcraft.

-14-

Partide detection is achieved with an Aitken nucleus counter. In this study

the EAA generally functioned wel so the di ffusion battery data, which requi re

extensive computer processing, were not analyzed.

Particles of intermediate size (see Fi g. 2.2) are measured with a Particle

Measuring System’ s (PMS) active scattering laser probe (ASASP-X) This devi ce

is essentially an open-cavity laser; the measuring principle is based on the

fact that a parti cle passing through the pumping cavity of a laser wi ll "detune"

the laser to an extent proportional to the size of the particle.

Medium to large-sized particles are measured with a PMS laser aerosol

spectrometer (LAS-200) and a forward light-scattering spectrometer (Royco 245)

These instruments determine particle sizes by measuring, with a laser and a

fi lament light source, respectively, the quantity of light scattered in the for-

ward di rection.

A microbalance cascade impactor (MCI suppl ied by EPA, was fitted with a

diffusion drier and placed near the inlet port of the large di ffusion drier.

The total length of plumbing from the MCI to the batch sampler port was about 30

cm with a residence time of less than 1 s. The MCI had 10 stages, between 0.05

and 25 pm; however, because of the sampl ing inlet, only a smal fraction of the

aerosol

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The 0,-instrument measures ozone by monitoring the chemiluminescence from3

the ozone-ethylene reaction, excess ethylene being suppl ied to a reaction

chamber through which ambient ai r is drawn.

The NO/NO,, monitor is a dual-reaction chamber device; in one chamber

measurements are made of the chemi uminescence of the NO+Og reaction by

supplying excess 0, to ambient ai r drawn into the chamber. In the other

chamber, excess On s suppl ied to the ambient ai r that has passed over a

catalytic-reducing agent to reduce any NO. present to NO. The difference bet-

ween the NO concentrations measured in the two chambers is attri butable to N0^.

The regul ar sampl ing system for halocarbons and hydrocarbons aboard the B-23

ai rcraft consists of one-half inch diameter stainless steel sampl e loop about

25 cm in length, through which ai r is pumped into stainless-steel canisters with

electropol ished interiors. An over-pressure of roughly 1 atmosphere is pumped

into each canister. Some canisters, fi led through this system, were suppl ied

to the Oregon Graduate Center (OGC for analysis. However, since in this project

we required most of the canister samples to be coincident with the fi lter

samples, the canisters were general ly fi led from the 500 A polyethylene bag

(rather than the stainless steel system). These sampl es were analyzed after

each fl ight by Lockheed-EMSCO, using gas-chromatography coupl ed with appropriate

detectors. Use of the polyethyl ene bag compromised the measurements of some

trace constituents (see Section 4.2).

Measurements of the concentrations of CO? n the ai r (in real time) were

made with a Mi ran/Foxboro long path IR sensor. Carbon monoxide (CO) measure-

ments were made with an Ecolyzer electrochemical oxidation instrument.

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2.4 General Meteorological Instrumentation

The general meteorologi cal instrumentation aboard the B-23 ai rcraft for

measuring temperature, humidity, horizontal and vertical winds, and ultra-violet

ight intensity is isted in Table 2.1. It is al standard equipment.

2.5. Data Processing System

Data flow charts are shown in Figs. 2.4-2.6. In-fl ight comments by the

pilots and crew are recorded on the ai rcraft instrumentation tape (Fig. 2.4).

Later these are reproduced for transcript typing. Hi gh-resolution data and

computer serial digital products (backup to di sk data) are frequency-shift-keyed,

demodul ated and processed into appropriate engineering units on a Raytheon 704

minicomputer (Fig. 2.4) The 7-track computer tape from the Raytheon can be

di rectly reprocessed into printouts or strip charts of the high-resolution data,

or transferred, vi a a PRIME 400 mi ni-computer, to 9-track tapes for further pro-

cessing (Fig. 2.5).

Normal ly, the serial digital stream from the ai rcraft computer is not

recovered from the instrumentation tape but is taken di rectly from floppy di sks

(Fi g. 2.5) and converted to 9-track tape vi a a Computer Automation’ s A-LSI-2

minicomputer.

Major computational efforts and graphics products are al handled on the

A-LSI-2 computer from a 9-track tape (Fi g. 2.6).

This is a well-proven system, which provides both flexi bi ity and redundancy

n data recording and processing.

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Figure 2.4 Flow chart for ai rcraft instrumentation tape to 7-track computertape and voice transcripts.

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A1RCRAFTCOMPUTERFLOPPYDI SKS

COMPUTERAUTOMATIONALPHA LSI 2COMPUTER

Figure 2.5 Flow chart for conversion of 7 track computer tapes and floppy disksto 9 track tapes and preliminary analysis hard copies.

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COMPUTERAUTOMATIONALPHA LSI 2COMPUTER

GRAPHS(Versotec 1110-A)

PRINTOUTS(Tolly T-2000)

Figure 2.6 Flow chart for processing 9 track tapes into final hard copyprintouts and graphics.

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3. SUMMARY OF RESEARCH FLIGHTS

On 2 July 1982 a prel iminary quality control check was made of the

instrumentation aboard the B-23 ai rcraft. The period between 22 July 1982 and

27 July 1982 was spent in Eugene, Oregon, where four research fl ights were made

through smoke plumes from the prescri bed areal burni ng of timber harvest resi-

dues ("broadcast slash burning") on units harvested to di fferent size specifica-

tions in the Wi lamette National Forest (Joule Sale area) During this period a

second qual ity control check was completed on the ai rborne instrumentation

system.

Two research fl ights were made during September 1982 over two prescribed

burns in the Twin Harbors area of Washington State.

Table 3.1 summarizes the research fl ights made in support of this

project.

-21-

TABLE 3. 1 SUMMARY OF RESEARCH FLIGHTS

Date"""OWFl ight Mi ssion Duration Activity

Number Number (Local times)

2 July 1982

19 July 1982 1052

22 July 1982 1053

23 July 1982 1054

24 July 1982 1055

25 July 1982 1056

26 July 1982 1057

(26 July 1982)

27 July 1982 1058

15 Sept 1982 1060

23 Sept 1982 1061

5 Oct 1982 1064

Qual ity control instrumentationcheck on ground.

1137-1506 Ai rborne Instrumentation fl ight check.

1312-1528 Ferry fl ight from Seattle to Eugene.

1 1449-1909 Slash burn fl ight (Oregon)

2 1508-1904 Sl ash burn fl ight (Oregon)

3 0809-1223 Sl ash burn fl ight (Oregon)

4 0926-1328 S1 ash burn f1 ight (Oregon)

Qual ity control instrumentationcheck on ground.

0858-1147 Ferry fl ight from Eugene to Seattle.

5 1313-1845 Sl ash burn fl ight (Washington)

6 1417-1806 Sl ash burn fl ight (Washington)

1310-1506 Sl ash burn fl ight (Washington).Fl ight aborted enroute to fi redue to aircraft enginemalfunction.

-22-

4. INSTRUMENT CALIBRATION AND DATA QUALITY CONTROL

4.1 Interim Calibration Performed In-house (29 June 1982)

(a) Ozone

This instrument was cali brated against a Monitor Labs 8510 Permacal 0^source (UV irradiation) which in turn was cali brated against neutral -buffered

potassium iodide. Ei ght points were used in the calibration. The data produced

the fol lowi ng cal ibration equation:

P (real 1.08 PQ (indi cated) 1.46 ppb

where P (real and Pn (indicated) are the actual concentrations of ozone and, the3 3concentrations as indicated by the instrument in ppb. The correlation coef-

ficient for the cal bration equation was 0.998.

(b) Nitrogen Oxides

The NO analyzer (both channels) was cal ibrated agai nst a Monitor LabsA

Permacal cali bration source (permeation tube and span gas dil ution) which in

turn was cal ibrated against gas-phase titration. Four points per channel were

used in the cal ibration. The resulting cal ibration equation was:

P.,. (real 1.65 P.,. (i ndicated) 7.876 ppb""X Xwhere the concentrations are in ppb. The correlation coefficient in this case

was 0.97.

(c) Carbon Dioxide

This instrument was cal ibrated against an in-house dynamic di lution system

employing concentrated CO. and ultra-pure nitrogen, whi le seven cal bration

poi nts were employed, the inherent nonl inearity of the instrument rendered a

single li near cal bration over the entire range of cal bration (0-4000 ppm)

-23-

impractical For example, the cali bration equation for the enti re range (based

on inear regression) was:

P 7.395 x 103 (absorption) 323.6 ppmLi’ft

with a linear regression coefficient of 0.937. This equation predi cts values

of P.. as much as 68% too high at lower P^ (relative to the actual cal ibra-CO^ 2tion values). If the linear regression is appl ied only up to 1000 ppm (a value

sti much in excess of any CO^ measured during the study) the calibration

equation becomes:

P 3.6514xl03(abso^ption) 7.939 ppmLUrt

with a correlation coefficient of 0.99. This equation predi cts P^ to within

16% of the actual cal ibration values and was employed in the data reductionfor

this project.

(d) Carbon Monoxide

No attempt was made to cali brate this instrument prior to the audit per-

formed by the Research Triangle Institute (RTI Therefore, the RTI audit

constitutes the cal ibration. It should be noted that this instrument suffers

from excessive zero drift and must be constantly re-zeroed in order toobtain

accurate readings.

(e) Integrating Sephelometer

The integrating nephelometer was cal ibrated by comparing the instrumentout-

put when viewing clear ai r and Freon 12 with the expected b^ values for these

substances. The fol lowing results were obtained:

-24-

Clear Air Freon 12

Observed: (1 .8+/-1.0) x 10" m"

Expected: 1.5 x 10"

3.4 x 10"4 m"12.4 x 10"4.

The di fferences between the observed and the expectedvalues were used to adjust

the data col lected in this field project.

4.2. Research Triangle Institute Field Audit

The results of the second audit of the instrumentationused aboard the UM ’s

*B-23 ai rcraft and by Lockheed-EMSCO are summarized in Table

4.1. The audit was

made at Mahlon Sweet Ai rport at Eugene, Oregon on 26 and27 July 1982. The

table lists the name, model and serial number of theinstrument the parameters

that were subject to audit, the range of themeasurements, and the slope, inter-

cept and correlation coefficient of the regression equationcalculated from the

audit data.

(a) Uni versity of Washington’ s Ai rborne Instrumentation

The ambient ai r qual ity analyzers aboard the UW s B-23 aircraft were

audited for measurements of the concentrations of carbon dioxide,carbon

monoxide, nitrogen oxides and ozone. The carbon di oxide, carbonmonoxide and

the total oxide of nitrogen (N0^) measurements exhibited satisfactory perform-

ance. The ozone analyzer reads systematical ly 15% higher thanthe RTI standard,

* Data taken from Murdock, R. W. (1982) "Second Audit of Ai rborneMon1tonng

Prescribed Fi res in the Mi llamette National Forest". Research TriangleInstitute Report No. RTI/NIX 26/00-02F. No unresol ved di fferences were notedbetween fi rst and second audit.

Organization

Universityof Washington’sB-23 Ai rcraftInstrumentation(at MahlonSweet Field,Eugene, Oregon)

Total oxides

Model 3205

Ghia Fi lter Sampler

TAB

Manufacturer ofInstrument, Modeland Serial Number

Foxboro Mi ran1A

Ecolyzer 2700S/N 1686

Monitor Labs8440 S/N 169

Monitor LabsS/N 1686

MRI NephelometerModel 1567

Rosemount

Cambridge SystemsModel TH73-244

TSI Quartz CrystalMi crobalance

LE 4. 1 SUMM;

Parameter

Carbondioxide

Carbonmonoxide

Nitric oxideNitrogen dioxide 0-0.2 ppm

of nitrogenOzone

^cat

Temperature

Dew point

Flow rate

Flow rate

t\RY OF AUDIT OF IN

Range ofMeasurement

0-50000ppm

0-10 ppm

0-0.2 ppm

0-0.2 ppm

0-0.2 ppm

Satisfactory

0-1 Lpm

0-100 Lpm

ISTRUMENTATI

RegressicAudit

Slope (m)

0.8877^0.6097^0.8573

1.1685AUDIT INCOMPLETE (see0.9366

1. 1548

ii

,i

+14.5+263.9

+0.11

-0.011 0.9994

Satisfactory

ON

n of Instrumeor’s "Standar

Intercept

-0.007

+0.001

Satisfactory

Satisfactory

Satisfactory

ntation Response tod" (y=mx+c)

Correlation(c) Coefficient

0.99270.9645

0.9996

text)0.9974

0.9999

POen

a/ Linear regression of CO^ based only on lower range of concentrations (0-2700 ppm) measured by instrument.j)/ Linear regression of CO^ based on ful range of concentrations (0-5000 ppm) measured by instrument.

TABLE 4. 1 (CONTINUED)

OrganizationLockheed-EMSCO

Manufacturer ofInstrument Modeland Serial NumberByron 401S/N 0306

ParameterTotal hydro-carbons (asmethane)

Total hydro-carbons (aspropane)

Non-methanehydrocarbon

Methane

Carbonmonoxide

Carbondioxide

Range ofMeasurement0-20 ppm

0-20 ppm

0-10 ppm

0-5 ppm

0-10 ppm

0-500 ppm

RegressionAuditor

Slope (m)1.0821

0.8514

0.963

0.9247

0.9403

0.9709

of Instrumental’s "Standard"

Intercept (c)+0.18

+0.11

-0.46

-0.11

-0.28

-2.53

.ion Response to(y=mx+c)

CorrelationCoefficient

0.9997

0.9984

0.9936

0.9987 ^0.9973

0.9998

-27-

with excel lent traceabi lity (correlation coefficient 0.9999) If the RTI stan-

dard is accepted, then the ozone concentrations reported hereafter shoul d be

reduced by 15%.

The audit showed the fl ow rates on the quartz crystal mi crobalance and the

Ghia fi lter sampler to be satisfactory.

The Rosemount temperature sensor, Cambridge Instruments dew point sensor

and the integrating nephelometer aboard the B-23 ai rcraft exhibited satisfactory

performance. The problem with the nitrogen oxides analyzer was not resol ved; we

accept RTI ’s analysis that the converter (NO to N0^) does not function linearly.

This results in NO? measurements which are systematical ly low relative to the

cal ibration values. The error woul d be of order 10% for concentrations of

NO n the sub-ppm range. The measurements of N0^ were, however, in excel lent

agreement with the cal ibration. These problems have no impact on the data

presented in this report.

(b) Lockheed-EMSCO Instrumentation

The Byron Model 401 gas chromatograph operated by Lockheed-EMSCO was

audited for measurements of the concentrations of carbon monoxide, carbon

dioxide, methane, total hydrocarbons and non-methane hydrocarbons. The

carbon dioxide channel exhibited excel lent performance, and the methane, total

hydrocarbon and carbon monoxide channel s satisfactory performance. The non-

methane hydrocarbon channel exhibited unsatisfactory performance (based on

the intercept of the linear regression equation)

-28-

4.3 Comparison of Plume Minus Ambient C02 Concentrations Measured by the

Oregon Graduate Center (OGC and Lockheed-EMSCO

The data avai lable for the comparison of the CO^ measurements made by OGC

and Lockheed-EMSCO from ai r samples col lected in the stainless steel canisters

via the polyethyl ene bag are shown in Table 4.2. Each of the canister samples

isted was analyzed by both systems with the indicated results. These results

suggest an analytical di screpancy of about +/-20%.

Two samples are avai lable which al low comparison of the polyethylene bag

sampl ing system (employed most of the time) with the stainless-steel sample loop

system (used for some of the OGC samples) The results of these comparisons are

shown in Table 4.3. They suggest an additional di screpancy, this time

systematic, of -20-60%, with the Lockheed-EMSCO concentrations greater than

those of OGC. This could possibly be a bag contamination problem, although it

is unclear how such a large di screpancy coul d arise. The quantity of data is

insufficient to warrant further discussion.

-29-

TABLE 4.2 COMPARISON OF OGC AND LOCKHEED-EMSCO MEASUREMENTS OF PLUME MINUSAMBIENT CO? CONCENTRATIONS COLLECTED IN STAINLESS STEELCANISTERS VIA THE POLYETHYLENE BAG

Date

23 July 1982

24 July 1982

24 July 1982

24 July 1982

24 July 1982

24 July 1982

24 July 1982

24 July 1982

SampleNumber

261

147

155

308

186

112

283

292

OGC Lockheed-EMSCO (L)(ppm) (ppm)

62

43

16

46

9

14

18

74

41

18

50

8

8

22

Ratio L/OGC

1.19

0.95

1. 13

1.09

0.89

0.57

1.22

-30-

TABLE 4.3 COMPARISON OF OGC AND LOCKHEED-EMSCO MEASUREMENTS OF PLUME MINUSAMBIENT C02 CONCENTRATIONS COLLECTED IN STAINLESS STEELCANISTERS VIA THE STAINLESS STEEL LOOP WITH THOSE COLLECTEDIN STAINLESS STEEL CANISTERS VIA THE POLYETHYLENE BAG

Date OGC(ppm)

Lockheed-EMSCO (L) Ratio L/OGC(ppm)

25 July 1982 6

26 July 1982 17

13.3 2.22

25 1.47

-31-

5. FLIGHT PROCEDURES AND DATA PROCESSING

5.1. Flight Procedures

Each plume was studied by flying the UW B-23 ai rcraft at various altitu-

des across the width of the plume, generally at a range of 3.3 km (2 nautical

mi les) from the burn. The range was initial ly determined by use of vi sual

terrain references and quadrangle maps. In cases where the plume fanned, or

ground references became obscured, the range from the burn was computed in

real-time using data from the doppler radar aboard the B-23 ai rcraft. Overall

our position repeatabil ity appeared to be excel lent.

5.2 Data Processing

The traverses of the plume at various altitudes at a given distance down-

wind of a burn were labeled A, B, C, D and E. where A, C and E were the top,

center, and bottom penetrations, respectively. The top and bottom penetrations

were chosen visual ly such that ~10% of the vertical dimension of the pl ume was

above A and below E. The center of the pl ume was estimated visual ly, but it

was general ly about hal fway between A and E. If the plume had suffi cient ver-

tical extent to sample at five levels, the B and n samples were taken midway

between A and C and C and E, respectively. When the pl ume lacked suffi cient

vertical depth for five traverses, the B and D samples were omitted.

Each cross section of the plume presented in this report consists of at

east the A, C and E traverses. The next cross section (i n time sequence) at

the same range uses the previous traverse (either A or E) as the fi rst

traverse of the new cross section. It is assumed that the burns were suf-

ficiently steady state so that each cross section can be considered as if each

-32-

of the plume traverses that comprise it were madesimultaneously. The bag and

batch samples were obtained as close as possible to the centerof the plume.

However, since they were taken over a minimum of 300 m path length and required

some degree of anticipation, they can be considered as located randomlyabout

the central region of the plume. Si nce each fi lter requi redat least two bag

samples, at least two traverses of the pl ume were made at each altitude.A

canister sample and particle size di stribution measurement were obtainedcoin-

cident with each fi lter bag sample. The cani ster and si zedi stribution data

are averaged when they are compared with the fi lter data.

The light scattering coefficient (b^^) as measured by the integrating

nephelometer. was the parameter selected to be representative of the plume

boundaries. Plume cross sections were created graphical ly by pl ottingthe

value of b every 2 s (130 m path length) for each altitude that wasscat

traversed. Plume center was defined as that where b^ reached peak values.

Multiple traverses at the same altitude were averaged. In documented cases of

substantial pl ume fanning with height, and/or multiple plume cores, thecross-

sections were made logical ly consistent with the avai lable data.

To calculate emission fluxes of any parameter, we assume that the para-

meter can be linearly scaled to b^. Hi gh-resolution data (13 sampl es/sec)

were used for b averages which were computed for times when thebatch

S C3T

sampler switch was in the "fi position. Using a least-squares fit,an

algorithm was derived for the relationship between the average value of

b and each flux parameter.scat

-33-

In the cases of the mass fluxes derived from the fi lters and the mass

monitor, separate algorithms were developed for the Washington and Oregon

units. The b cross sections were contoured, and the grid areas, or areasS CdL

between b contours, were determined. The cross sections were thenS Cd C

divided elevationally by wi ndspeed (which was interpolated from soundings

taken with the pi lot bal loon closest to the time of the cross section). An

average windspeed was determined for each grid area. The emission flux is

given by:

F1 ux=E (gr1d area) x(windspeed) x(average parameter concentration in grid area)."’

where, indi cates the b contour level

Mass fluxes were derived from linear equations relating measurements of

b to the data from the weighed fi lters, the mass monitor (

-34-

TABLE 5.1 ALGORITHMS RELATING b^^ TO MASS CONCENTRATION

a) Filters-3\ i-t. /^~l\n f\ i m-’

*Mass concentration (ug m" [bscat (m" )] (1. 3 x 10 + 150Number of samples 44 (a1 data included)Correlation coefficient 0.78 5 _2Mean mass concentration/mean b ^

1.77 x 10 pg m

Oregon Samples

3 1 5Mass concentration (ug m" [bscat (m" )^ (2-32 x 10 + 24Number of samples 20 (2 extreme values deleted)Correlation coefficient 0.88 5 _^*Mean mass concentration/mean b^^ 2.44 x 10 yg m

Washington Sampl es5

Mass concentration (ug m" [bscat (m- ^ (1*68 x 10 119Number of samples 18 (4 extreme values deleted)Correlation coefficient 0.92 5 _g*Mean mass concentration/mean bscat 1’44 x 10 ^9 m

b) Mass monitor (

OREGON ONLY

5. 1. A plot of the weighed fi lter mass concentration versus the light scattering coefficient (b ^)together with the inear regression and the 95% confidence intervals for the Oregon data set.

NRSH INGTON ONLY

^.^p^^,^^^.^^^^^^

O R E G O N

0 .00083 .00167 .00250 .00333 .00417 .00500

BSCRT (m"1) ,Figure 5. 3. A plot of the mass moni tor mass concentration versus the light scattering

coefficient

(b ) together with the inear regression and the 95% confidence interval for theOregon data set.

scat 3

W A S H I N G T O N

-39-

5.3. Physical Interpretation of b^^ Al gorithms

It must be noted that the relationships between the light scattering

coefficient and aerosol mass that have been reported in the literature have

usual ly been the result of a very limited data set and thei r authors have merely

ratioed b and mass and averaged the result (cal led the ratio method). ForS CBL

2 -1example, in our earl ier work we found values between 1.3 and 5.8 m g for this

2 -1ratio. White (1981) reports a range of values from 1.5-15.4 m g for various

sources. Anderson et at (1982) reports b -to-aerosol mass ratios of

1.9-3.4 m2 g" from a study simi lar to the present one. In the present study2 -1 2 -1

the mean value was 5.6 m g with mean values of 4.1 and 6.9 m g for the

Oregon and the Washington fi res, respectively.

The ratio method assumes that each particle contributes to b^^ in propor-tion to its mass; in fact, we know that this is not the case. As described in

more detai in Section 6.5, for the size distributions observed in this study,

the submicron particle mass completely dominates b It is some combination

of the distribution of supermi cron particles and the data s inherent noise that

produces the signi ficantly non-zero intercepts of the algorithms in Table 5.1.

That this departure from a 1:1 relationship is mathemati cal ly secure for the

fi lter data is indicated by the number of sampl es (44) and the satisfactory

correlation coefficient (0.78). The correlation coefficients are signi ficantly

improved if the data is divided into Washington and Oregon sets and a total of 6

"extreme" values are excluded. The correlations coefficients for the Washington

and Oregon data sets are 0.92 and 0.88, respectively. However, there is no apparent

-40-

basis for excluding the extreme values other than that they appear to be

"outl iers". Thus, for the burns studied, the ^cat"1 1"6^ fit a1gorithm

provides, in some ways, a superior predictor of smoke mass than does the ratio

method. The disadvantage of the algorithm is its questionable value at the

edges of plumes, where b^^ is smal l For both reasons, and also because of

the historical use of the ratio method, we wi use both the ratio method and

the b -l inear algorithm method in later sections.s cdc

As an aside, the b -l inear algorithm that results from Anderson et al ^sS C^L

data is:

mass concentration (ug m’3) -0.042 (b^g^xlO" m" + 990

with a correlation coefficient of -0.13. This result has neither predictive

value nor does it support a 1: 1 relationship between b^^ and mass. This

further indicates the need for a substantial data set in order to reduce

statistical uncertainties.

-41-

6. PRELIMINARY RESULTS AND ANALYSIS

In this section we present some of the results of the ai rborne measure-

ments of the slash burns and some preliminary interpretationsof the data.

6.1. Characterization of the Cross-Section of the Plumes

Using the methods described in Section 5.2, all of the ai rborne measure-

ments (except those which were clearly unsuitable due to non-perpendicular

penetrations of the plumes or gross changes in burn characteristics) were

assembled into cross-sections of ight-scattering coeffi cient. Illustrative*

exampl es are provided below for each of the burns investigated in thisstudy.

6.1.1. 23 July 1982

This burn was on a hil lside, just below a ridgel ine in rough terrain.The

plume initial ly rose nearly verti cally through a boundary layerinversion, and

was then carried off horizontally, at an altitude of 1.7 km by the windsaloft.

The plume was initial ly only -250 m thick with a well-defined axial core(Fig.

6.1 Additional fuel added to the burn after -1640 PST increased thedepth of

the pl ume to -400 m (Fi g. 6.2) but by 1720 PDT the plume had stabil ized back to

a thickness of -280 m. By 1720 PDT the pl ume was substantial ly more complex

(Fig. 6.3) with light winds and terrain features introducing portions of the

pl ume from earlier times into the cross-section. The secondary coreof the plume.

located at an altitude of 1.65 km and 1.2 km to right of center (Fig. 6.3)

was part of the "old" plume. In post-analysis we removed from the data set

* A ful set of cross-sections is on fi le at the USDA Forestry SciencesLaboratory, 4043 Roosevelt Way NE. Seattle. WA, 98105. Copies can beobtained from that source.

2.0 .0 0 1.0 2.0

DISTANCE FROM PLUME CENTER (KM)

3.0

Fig. 6.2dicular toheavy barssection is

Verticalthe longindicatebased on

cross-section of the light-scattering coefficient (in units of 10-3 m-1) measured perpen-axis of the plume from the prescribed burn on 23 July 1982 at 3.3 km from the burn. Thethe regions over which the batch sampler on the B-23 ai rcraft was operated. The crossai rborne measurements taken during sequence Vif. between 1640-1723 POT.

L̂JQD

<

1.0 0 1.0

DISTANCE FROM PLUME CENTER (KM)

Fig. 6.3dicular toheavy varssection is

Vertical cross-section of the light-scattering coefficient (in units of 10-3 m-1) measured perpen-the long axis of the plume from the prescribed burn on, 23 July 1982 at 3.3 km from the burn. Theindicate the regions over which the batch sampler on the B-23 ai rcraft was operated. The crossbased on ai rborne measurements taken during sequence #3 between 1719-1745 POT.

-45-

we removed from the data set encounters with smoke that were obviously separated

from the main plume. However, in this case (and the fol lowing) whenever "old"

smoke merged with "new" smoke, we were unable to objectively partition the data.

Consequently, this cross section and the fol lowing (Fi g. 6.4) tend to exaggerate

the emission fluxes. When the plume sketches and photographs from the patrol

ai rcraft aloft become avai lable it may be possible, through further analysis, to

remove this ambiguity.

^Q=)

<

1.0 0 1.0

DISTANCE FROM PLUME CENTER (KM)

Fig. 6.4dicular toheavy barssection is

Verticalthe longindicatebased on

cross-section of the light-scattering coefficient (in units of 10"3 m"1) measured perpen-axis of the plume from the prescribed burn on, 23 July 1982 at 3.3 km from the burn. Thethe regions over which the batch sampler on the B-23 ai rcraft was operated. The crossai rborne measurements taken during sequence )jt4 between 1744-1814 POT.

-47-

6.1.2. 24 July 1982

Initially, this plume was low and did not rise above local ridgel ines,

making ai rborne sampl ing nearly impossible. An attempt was made to rectify

this by adding more fuel this caused the pl ume to ri se to more than 3500 m.

However, before a series of ai rborne cross-section measurements could be

completed, the plume col lapsed to much lower altitudes. As a result, a steady-

state assumption for this burn was not justi fied and no cross sections were

compiled.

6. 1.3. 25 July 1982

This burn produced a good stable plume for about 2.5 hours. The cross

sections al look similar to the one shown in Fi g. 6.5. Only sequence 3, taken

between 1037 and 1054 PDT, departed from a completely stable appearance; the

plume contained a significant amount of smoke ~300 m below the average base of

the plume at -1900 m MSL.

6. 1.4 26 July 1982

Stable weather conditions al lowed good measurements to be obtained on

23 and 25 July. However, on 26 July as broken ci rrus and ci rrocumul us and

towering cumulus on the horizon to the east invaded the sky, sampl ing conditions

deteriorated. Despite changes in atmospheric stabil ity seven cross sections of

good qual ity were obtained in the pl ume from this burn. Only sequences 3 and 4

(from 1114-1159 POT) show signi ficant deviations from an otherwise vi sual ly

steady plume. The thickness of the plume decreased during sequence 3, whi le it

increased during sequence 4; the other cross sections look very much like the

one shown in Fig. 6.6.

c

1.2 .8 .4 0 .4 .8

DISTANCE FROM PLUME CENTER (KM)

Vertical cross-section of the light-scattering coefficient (in units of 10the long axis of the plume from the prescribed burn on 25 July 1982 at 3.3indicate the regions over which the batch sampler on the B-23 ai rcraft wasbased on ai rborne measurements taken during sequence #2 at 1021-1041 POT.

"3 m~1) measured perpen-km from the burn. Theoperated. The cross-

’

2.1

L̂U

2.0

<

.91.2 0.8 0.4 0 0.4 0.8 1.2

DISTANCE FROM PLUME CENTER (KM)

Vertical cross-section of the light-scattering coefficient (in units of 10~3 m~1 measured perpen-the long axis of the plume from the prescribed burn on .,26 July 1982 at 3.3 km from the burn. Theindicate the regions over which the batch sampler on the B-23 ai rcraft was operated. The crossbased on ai rborne measurements taken during sequence #5 between 1157-1219 PDT.

-50-

6.1.5 15 September 1982

This was the fi rst burn in Washington and it was significantly larger than

any of the Oregon burns. The pl ume was visual ly rather stable and steady. The

cross sections show a smal plume initially, fol lowed by a very steady period

from 1500 to nearly 1600 PDT, fol lowed, in turn, by a sl owly shrinking plume.

Fig. 6.7 is representative of the large and complex plume encountered.

6.1.6 23 September 1982

This plume showed large departures from visual steady state. This

situation was further compl icated by a substantial turning of the wind di rection

with height within the range of altitudes occupied by the plume. Obscuration of

surface terrai n features by smoke near the burn, and off-scale readings of the

ight-scattering coefficient at a range of 3.3 km, prompted us to move to a

range of 6.6 km in order to obtain cross-sectional measurements. The results

depicted in Fig. 6.8 are typical of the compl ex plume encountered.

6.1.7 Summary of Plume Cross-Sections

The cross sections shown in Figs. 6.1-6.8 are an important step in quan-

ti fying the nature of the plumes. Further quantitative information is provided

in Table 6.1 which lists the average values of b^^ between contours (shown in

the cross sections) and the area between that contour interval multipl ied by

the wind speed (the ai r volume fl ux) for al val id cross sections. The tables

can be used to compute the emission flux of any parameter that can be related to

^caf

’.

^Q=)

.8 .4 0 .4 .8 1.2

DISTANCE FROM PLUME CENTER (KM)

Fig 6 7 Vertical cross section of the light scattering coefficient (In units of 10-3 m-1) measured perpen-dicular to the long axis of the plume from the prescribed burn on 15 September 1982 at 3.3 km from the burn.

The heavy bars indicate the regions over which the batch sampler on the B-23 ai rcraft was operated.

The cross section is based on ai rborne measurements taken during sequence N between 1525-1610 PDT.

Fig. 6.8 Vertical cross-section of the light-scattering coefficient (in units of 10"3 m-1 measured perpen-dicular to the long axis of the plume from the prescribed burn on 23 September 1982 at 6.6 km from the burn.The heavy bars indicate the regions over which the batch sampler on the B-23 ai rcraft was operated. Thecross section is based on ai rborne measurements taken during sequence #3 at 1608-1647 POT.

2.0 1.6 1.2 .8 .4. 0

DISTANCE FROM PLUME CENTER (KM)

-53-

1 COMPILATION OF THE VOLUME FLUX OF AIR AND THE ASSOCIATED VALUE OFTHE LIGHT-SCATTERING COEFFICIENT (bg^) TAKEN FROM THE CONTOUREDCROSS-SECTIONS OF b AND THE MEASURED HORIZONTAL WINDS

SC3L

Cross-SectionSequence

ht Number

1982 1

2

3

4

1982 1

2

3

4

5

TimeInterval(PDT)

1606-1644

1640-1723

1719-1745

1744-1814

0950-1009

1021-1041

1037-1054

1051-1108

1104-1120

AveragebscatValue forContourInterval(10-3 m- )

2.451 .450.7250.225

2.7252.2251 .450.43

3.7253.2252.451 .450.43

3.7253.2252.451 .450.43

1 .2250.7250.225

1 .7251 .2250.7250.225

2.451 .450.7250.225

2.451 .450.43

2.2251 .7251 .2250.43

AreaofContourInterval

(105 m2)

0.1341 .5843.0402.638

0.2491 .2553.3088.968

0.1040.4202.8822.3343.650

0.0060.2191 .7312.3823.991

0.3510.9681 .545

0.3410.6851 .5452.723

0.0073.4213.4534.213

0.6173.0582.984

0.0361 .0332.5674.016

"TOO-Speed

(m s-1 )

5.04.64.74.8

3.03.03.13.5

1 .01 .61 .71 .71 .9

2.02.02.02.02.0

4.94.44.7

7.07.07.06.8

11 .09.7

10.010.1

10.810.810.8

9.010.410.010.2

Vol ume Fluxof Air

(105 m3 s-1

0.6707.28814.29012.664

0.7473.73510.25631 .390

0. 1040.6734.8993.9686.934

0.0120.4373.4614.7647.981

1 .7224.2607.263

2.3854.79410.81818.508

0.07933.18334.53242.555

6.66033.03032.227

0.32310.74025.67440.963

-54-

TABLE 6. 1 (CONTINUED)

DateMissionNumberUM FlightNumber

25 July 19823

105626 July 1982

41057

Cross-SectionSequenceNumber

6

1

2

3

4

5

6

7

TimeInterval(PDT)

1 11 7-1 1 33

1041-1059

1053-1118

11 14-1124

1140-1200

1 157-1219

1210-1231

1225-1245

Average^catVaTue forContourInterval(10-3 m-1

2.451 .450.43

1 .2250.7250.225

2.7252.2251 .450.43

2.451 .450.43

3.2252.7252.2251 .450.43

2.7252.2251 .450.43

2.7252.2251 .450.43

2.7252.2251 .450.43

AreaofContourInterval

(105 m2)

1 .3703.0004.430

0. 1580.8351 .122

0.0540.3161 .0081 .782

0.0140.4120.818

0.0320.3150.8351 .7612.980

0.0500.4121 .0221 .789

0.1580.5631 .1192.170

0.0970.5201 .1011 .972

"WTnd---Speed

(m s-1)

9.810.19.8

5.05.05.0

5.95.65.45.3

5.05.05.0

8.07.56.26.06.2

6.87.07.27.3

5.75.55.55.4

5.05.05.05.0

Vol ume Fl uxof Air

(105 m3 s-1

13.42630.30043.411

0.7894.1775.61 2

0.3171 .7675.4419.446

0.0722.0624.088

0.2572.3665.18010.56618.475

0.3412.8867.35813.062

0.9003.0966.154

11 .715

0.4842.605.5049.861

-55-

TABLE 6. 1 (CONTINUED)

DateMissionNumberUW Fligl-Number15 Sept

5191

1060

it

embi82

Cross-SectionSequenceNumber

er1

2

3

4

5

6

1416-1428

1421-1501

1459-1529

1525-1610

1608-1645

1644-1721

TimeInterval(PDT)

Averagebscat V811"8for ContourInterval(10-3 m-1

12.9010.908.906.903.250.725

10.908.906.904.902.901 .175

12.910.98.96.94.92.91 .175

12.910.98.96.94.92.91 .175

12.910.98.96.94.92.91 .175

10.98.96.94.92.91 .175

AreaofContourInterval(105 m2)

0.0570.0740.0950.1360.3730.151

0.3580.6461 .6572.4673.7033.641

0.2440.7671 .6352.3103.6792.9983.808

0.0360.2360.5601 .2901 .8502.8692.639

0.1510.1070.5021 .4993.0123.8513.292

0.1220.3230.7964.1743.4782.374

WindSpeed

(m s-1

16.016.016.016.016.016.0

13.311 .911 .811 .210.09.7

14.411 .311 .410.710.312.310.3

17.015.816.014.915.614.013.9

11 .011 .112.612.613.012.912.2

12.712.613.214.313.513.7

Volume Fluxof Air

(105 m3 s-1

0.9121 .1841 .5202.1765.9682.416

4.7617.68719:55327.63037.03035.318

3.5148.66718.63924.71737.89436.87539.222

0.61 23.7298.96019.34028.86040.16636.682

1 .6611 .1886.32518.88739.15649.67840.162

1 .5494.06910.50759.68846.95332.524

-56-

TABLE 6. 1 (CONTINUED)

DateMissionNumberUM Fl ightNumber15 September

19825

1060

23 September1982

61061

Cross-SectionSequenceNumber

7

2

3

4

5

TimeInterval(PDT)

1713-1735

1558-1 612

1608-1647

1642-1710

1709-1716

Average’’scat Valuefor ContourInterval(10-3 m-1 )

8.96.94.92.9

1 .175

6.455.454.453.452.451 .450.725

6.45*5.454.453.452.451 .450.725

7.456.455.454.453.452.451 .450.725

5.454.453.452.451 .450.725

AreaofContourInterval(105 m2)

0.0860.1150.6021 .0040.889

0.0210.2870.5960.6881 .1551 .5631 .112

0.0640.3660.5880.8901 .4121 .5071 .369

0.0430.3730.6091 .5641 .6062.61 12.4601 .879

0.1860.6820.4660.7030.9680.839

UmdSpeed

(m s-1 )

13.013.614.314.114.1

13.012.111 .912.011 .611 .811 .9

13.012.212.311 .911 .712.211 .6

12.012.212.211 .212.01 1 .41 1 .51 1 .6

10.010.110.310.210.210.4

Volof

(105 m3 s-1)

ume FluxAir

1 .1181 .5648.60914.15612.535

0.2733.4737.0928.25613.39818.44313.233

0.8324.4657.23210.59116.52018.38515.880

0.5154.5517.430

17.51719.27229.76528.29021 .796

1 .8606.3434.8007.1719.8748.726

-57-

6.2 Some Characteristics of the Particles in the Plumes

In a previous series of ai rborne measurements that we obtained in the

plumes from prescribed burns (Stith et at 1981) we noted that both the number

and the mass distri butions of the particles in the pl ume were generally domi

nated by a concentration peak at ~0.1 pm diameter; a much less prominent peak at

0.5 urn was also noted. However, with the instrumentation then avai lable,

information on particles > 10 urn present in number concentrations 10 ym can be obtai ned at concentrations down to

~10"3 cm"3. Al so, the avai labi ity of new particle-size measuring instruments(see Section 2) extends our measurements to particles ~3000 urn in diameter pre-

sent in concentrations down to -lO^cm" These new observational capabi itieshave resulted in a revision in our view of the role of supermi cron particles in

smoke from prescribed burns.

6.2.1 Parti cle Size Distributions

The particle size distribution shown in Fi g. 6.9 il lustrates many of the

features that were found to be typical of the smoke from the prescribed burns

investigated in this study. The particle size distribution shown in Fig. 6.9

was obtained on 23 July 1982 at a range of 3.3 km for the burn and near the

plume center on traverse "C". Before discussing some of the features of this

distribution, we need to make a few caveats about the measurements.

* Al of the particle size distributions measured during this project, anda discussion of the di fferently weighted (number, surface and volume)distributions, are contai ned in Data Supplement #3.

-58-

o (5 E^S< i-.’j’i’C^ 2’j2a p.orca c^?

0)

0 -^0 +3"

00

c^"

00

(V"

m

sroy-a""’L3D

Do~-^o

Q0’L3

Sg

00-- \00

"- \\

00

rf-

00

in--------------|-------------n----------- |,.,i..,.,’-3.00 -2.00 -1 .00 0.00 1.00 2.

++

\ :\ t\ t\ t\ .\ .\\ .\ +\ ^\ + .+\ . .

\ 4 .\ ^\ ^ 0\

\ ^\\ .\

\\\

Fig. 6.9 Number concentration versus size of particle measured in the plumefrom the prescribed burn at 1742 PDT on 23 July 1982 3.3 km downwind of theburn. The dashed line shows a typical ambient particle size distribution.

-59-

As discussed in Section 2, the use of the batch samples shoul d resol ve

any timing difficulties resulting from the fact that the four particle-size

measuring instruments operate on di fferent time sequences. Nevertheless, some

oss of data accuracy can occur through operational errors. In order to be con-

sidered valid data, we requi re smooth transitions between the measurements from

the various particle-size measuring instruments. For the ranges shown in Fig.

2.2, each instrument is most accurate at the small size end of its range and

general ly least val id (due to counting statistics and sedimentation) at the

large size end. The most common points of concern in such data are poor tran-

sitions between the measurements obtained with the EAA and ASAS (about 20% of

cases) and a rough transition between the measurements from the ASAS and LAS in

the range 0.7 2 pm. The latter discrepancy is of some importance, since this

is the size range where our previous smoke studies (Stith et a1 1981) showed a

secondary peak in concentrations. Measurements obtained with the ASAS in this

present study tend to support a peak at 0.7 urn, but data from the LAS does not

show this peak.

The measured particle size distri butions showed simi lar shapes and gross

features throughout the duration of each burn, as well as for al of the burns

studied (see for example Fig. 6.10). However, some interesting di fferences were

noted from the studies of Stith et a1 (1981) Although there is a prominent

mass peak centered at 0.1 pm, the peak in the number concentration of 0.1 urn is

now a secondary feature. Measurements from the EAA show concentrations sti ll

increasing below 0.01 urn (the imit of this instrument) indicating the possi bi-

ity of a (nucleation) peak in the number distribution below 0.01 pm.

-60-

0

t^ ^< ccr Er- z ^UJ

^ j-8 "CPLU 0

=> -0; >10-2 10’ 10 10’ 102 10

PART ICLE D A METER D (/im)Fig. 6.10 Number concentrations versus size of particles measured near thecenter of the plume and 3.3 km downwind of the burn on 23 July 1982 at 1636PDT (heavy solid line) IT^tl PDT (dashed line) and 1759 PDT (solid line)The ambient particle size distribution is also shown (dotted line)

-61-

However, since the cumulative particle number from the EAA is in reasonable

agreement with the "total aerosol concentration measured by the Aitken nucleus

counter, the peak must be near 0.01 urn. Furthermore, most of the submi cron par-

ticle mass and ight scattering are stil associated with the 0.1 urn number

peak.

The most dramatic difference between the present measurements and those

reported by Stith et at (1981) has to do with the supermicron particle volume

di stribution, for which our new particle sampl ng system provides superior resolu-

tion for particles with diameters up to ~45 urn. Fi gure 6.10 shows that in our

current data the supermicron particle peak is not resol ved; the volume continues

to increase with increasing size to the limit of the measurements. Our previous

smoke data show a minor mass peak at ~10 pm and the vast majority of the mass

located in the submicron peak. The higher concentrations of supermi cron par-

ticles that we measured in this study, compared to Stith et al ’s measurements,

are almost certainly due to improved sampl ing techniques. These new observations

affect estimates of TSP, as wi be discussed below.

It shoul d be noted that a substantial fraction of the particles in the

plumes had diameters >45 pm; this was supported by the pi lot ’s observation that

we were col lecting mi imeter sized pieces (stil smoldering?) under the

wi ndshield wiper blades of the ai rcraft. The shapes of these parti cles are

shown in Fi g. 6.11. The largest particle in this sample is about 4 mm long.

-62-

FLT*1060. PROBE*5. ID*060. 17; 09:46

rnTirrNOT^^iiiiiirfrriiir’rrir^-";: ;?;; :?;;;s;;;;;;?; ?:i=>::s;;^;:;=;; ;;

FLT*1060, PROBE*4, ID*060. 17: 13:01

T#1060 PROBE*5 ID*060< 17; 13; 13 inii^i ynit/di iii m

ISyiaiiwiiiiwitflteTritLiHr’^HH ^f irWt r hWftLHHt’H l^tiiiiiPBiwff^^’LSiR&l^rl&^^FLT*1060^PROBE#4, ID#060. 17:20:55 1- 1- 11 A ^

^ ILr illLHt f It |l t l l! lilLrHtl[ H lhH4LF IHllKlllK HILWc\ T^IOCCT ponRFA^ TT^ftRfiB 17" 24" 50’’^BBi^raitH’ir^SirnS?ir^mii(H:ikir - iLiHtMrLUii4ii .L^]ri^iL"- ’-. ’-^^-^ ’If naFLi#\Q6Q, PROBE*5/ ID*060. 17:27:20

FLf*i060’," PROBE*5^"iD*060," 17:27:40

rt|i’i!

iH HLri^t [llNll ffiFL:^*1060^">’PROBE*4," ’ID*060. 17:27:45

?’ r i kl i l ^ n ;?-_

FLT*iaG0. PROBE*5, IDw060. 17:33:56

Fig. 6.11 Shadow images of ai rborne particles observed with the laser camera incross-section sequence #2 through the plume from the burn at ~1727 PDT on 15September 1982. For Probe 4, the vertical frame size is 800 urn, and for Probe 5,it is 3200 urn.

-63-

The other three laser cameras aboard the B-23 ai rcraft al so detected the

large particles. Although thei r counting statisti cs are only just satisfactory,

the shape of the distri bution can be seen in the raw data plot taken near pl ume

center at 1427 POT on 15 September 1982 (Fi g. 6.12). The measurements from the

instruments agree reasonably wel with simultaneous measurements obtained from

the aerosol system, but there is a change in slope at the overlapping intersec-

tion of the two data sets (Fig. 6.13). The point to note is that these curves

show that the peak in the volume of the supermi cron particles is stil0

not resolved even by our extended size measurements; the total volume of the

particles is sti increasing for parti cles above 1000 urn in diameter.

While the submicron particles dominate visibi lity reduction by the pl ume,

and the impact of the plume over large travel distances, it is clear that at

3.3 km downwind of the prescri bed burns that we studied the supermicron par-

ticles dominated the total mass of particles in the plume. This result has a

significant effect on our interpretation of the aerosol fi lter data and how we

define the emission factor (see Section 6.5).

-64-

00

OJ

0rS-

0̂0o

Od-0

QQ’^02LCD’T’-CD0

-00

(\1-

0C3

(T>-

00

=r

QQ

LD-

"0

A

..................A...

j!

00

^A

4s.A

............^......

^A

^00

00 2

^ 0̂o^0

00

00 3 00 4 0-’

Fig.. 6. 12 Number concentration versus particle size measured with a lasercamera on the B-23 ai rcraft near the center of the plume 3.3 km downwind of theburn at 1427 PDT on 15 September 1982.

-65.

10’2 0" 10 0’ \02 103PART IC LE DIAMETER D (/iM )

Fig. 6.13 Number concentration versus the size of particles measured withthe aerosol system near the center of the plume 3.3 km downwind of the burnon 15 September 1982 at 1K27 PDT (heavy line) and 1727 PDT (lighter line)The dashed extensions are measurements from the laser cameras.

-66-

6.2.2 Average Characterisitics of the Particle Size Distributions

The characteristics of the particle size distri butions are best seen

in the averaged and summed characteristics of the mean number diameter (MND) of

the particles, thei r mean volume diameter (MVD) and the total particle volume

(TPV) for particles < 43 pm in diameter. Plots of these parameters, as a func-

tion of time after burn ignition, reveal a number of signi ficant di fferences

between the burns that we studied.

Fi gure 6.14 indicates the generally steady-state nature of the pl ume from

the burn on 23 July 1982 over the period 50-140 min after ignition; the MND is

steady between 0.02 and 0.03 urn and the TPV is steady near 200 pm cm" The MVD

is more variable, ranging from 8 17 pm, and is evidently correlated with the

TPV. The altitude of the plume center rose by less than 150 m during this

period.

In contrast, on the 25 July 1982, which also featured a "wel l-behaved"

plume (although it gained substantial ly in altitude as the burn progressed)

shows a general increase in MVD and TPV as a function of time after ignition

(Fi g. 6.15). This behavior was repeated on 26 July 1982 (Fi g. 6.16). In both

cases the MVD was initially ~1 urn and increased to -10 urn by about 2 hours after

ignition. The MND’s show little variation.

The larger burn in Washington on 15 Spetember 1982 (Fi g. 6.17) shows

far more variabil ity, despite a visual ly fai rly steady plume.

SEQUENCENUMBER

iT

S0o

600^3.o^ttinr

400$ ^-i^? S0-1

200 1- 0TOTAL VOLUME

.03

.01

ALTITUDEOF PLUMECENTER

1.8

1.7

1.6

S

ûQ3-<

50 60 70 80 90 100 10 120 130 140

TIME ELAPSED AFTER IGNITION (MIN)

Pig. 6.14 Characteristics of the particles near the center of the plume on

traverse "C" 3.3 km downwind of the burn on 23 July 1982 as a function of

time after ignition.

40 50 60 70 80 90 100 110 120

TIME ELAPSED AFTER IGNITION (MIN)

Fig. 6.15 Characteristics of the particles near the center of the plume ontraverse "C" 3.3 km downwind of the burn on 25 July 1982 as a function oftime after ignition.

7 SEQUENCE(-1 NUMBER

o

u10

>00 3.J 2

^̂t000 $ ^Q. UJ0 ^ 3^2.2

2.0S

^UJQ

1.8 ?

1-6 <

50 60 70 80 90 100 10 120 130 140 150

TIME ELAPSED AFTER IGNITION (MIN)

Fig. 6.16 Characteristics of the particles near the center of the plume ontraverse -C" 3.3 km downwind of the burn on 26 July 1982 as a function oftime after ignition.

Pig. 6.17 Characteristics of the particles near the center of the plume ontraverse "C" 3.3 km downwind of the burn on 15 September 1982 as a functionof time after ignition.

120 140 160 180

TIME ELAPSED AFTER IGNITION (MIN)

-71-

The second Washington burn on 23 September 1982, was studied at 6.6 km

downwind (Fig. 6.18). Visual ly, the plume was less steady than the pl ume on

15 September; again there was only sl ight correlation between MVD and TPV.

The MVD decreased throughout the duration of the burn; it had an initial value

~6 urn and finished at ~2 urn, with a discontinuity at ~100 min after ignition

when both MVD and TPV increased sharply. The MND shows signs of being anti-

correlated with MVD.

An interesting feature of the data sets are the two cases where there is a

clear positive correlation between MVD, TPV and plume rise, and the other three

cases where this is correlation was not evident. The two cases where there was

a positive correlation seem to indi cate a relationship between the intensity of

the burn (as indicated by pl ume rise) and the lofti ng of ever larger debris into

the plume. The fact that there are weak indi cations that the MND decreases as

MVD and TPV increase (see also the 25 and 26 July cases) suggests that com-

bustion efficiency al so played a role. Thus, as the intensities of the burns

increased, more complete combustion produced smal ler "combustion nuclei but

simultaneous increases in the velocity and turbul ence of the ai r increased the

concentrations of partial ly combusted fuel and other debris in the pl umes.

Pig. 6.18 Characteristics of the particles near the center of the plume ontraverse "C" 6.6 km downwind of the burn on 23 September 1982 as a functionof time after ignition.

-73-

6.2.3 Apparent Density of the Particles

Simultaneous measurements of the particle volume distribution, the

particle mass distribution (with the cascade microbalance) and the mass of

particles

-74-

TABLE 6.2. APPARENT DENSITY OF PARTICLES IN PLUME

a) Mass Monitor Data_o

Mass concentration (ug m"3) 2.6 (aerosol volume in urn cm ) + 38Number of sampl es 247Correlation coefficient 0. 90 _^Density of particles 2.6 +/-0.08 g cm"

b) Cascade Microbalance Data

Mass concentration (ug m"3) 2.2 (aerosol Volume in urn3 cm"3) + 35Number of samples 115Correlation coefficient 0.63Density of particles 2.2 +/-0.25 g cm-3

-75-

distributions. we divide by a (rounded-off) particle density of 2.0 g cm"

(We wi use this density in the remainder of this report. However, we must

emphasize both the uncertain value of this density and the fact that it is not

clear to us how the accuracy of the value can be improved. Some results are

shown in Fig. 6.19, where it can be seen that the cascade microbalance reprodu-

ces the submicron mass peak detected by the particle size-measuri ng system.

However, as expected, the very smal sample flow for the cascade mi crobalance

prevents it from col lecting a weighable sampl e for particles >5 urn.

we bel ieve that the measurements of the size spectra of particles converted

to a mass distribution, using a derived apparent particle density, is the more

general ly valid and defensible approach to obtaining size-segregated mass

distributions in the plumes than are the measurements from the cascade

microbalance.

n

160

^ 120=to0>0

o

>̂

80

40

(c)

-3

9/23/821718

-2 0

LOG D (/xM)

Fig. 6. 19 Vol ume concentration versus size of particles measured with the aerosol sizingsystem near the center of the pl ume from the burns (a) at 0954 POT on 25 July 1982; (b)at 1605 POT on 23 September 1982; (c) at 1718 POT on 23 September 1982; and (d) at 1700 PDTon 23 September 1982. The dashed lines show resul ts derived from the cascade microbalanceimpactor (mass/density of particles

-77-

6.2.4 Aerosol Elemental Analysis

In addition to weighing the filters Crocker Laboratory performed an elemen-

tal analysis by Proton Induced X-Ray Emission (PIXE ). Me have appl ied the

matrix correction factors for Na. A1 Si and C1 which had correction factors

>10%, al other elements had correction factors

TABLE 6.3 P.XE ANALYSES OF EMISSIONS FROM THE SLASH ^NS (The numbers 1n th. body of the table are the concentrations or the specified element in .9 m-3)-3,*

(a) UM Flight 1054 on 23 July, .1982 (V. Br- and Ti wre not detected.)

Filter

A5(Amb)A6A7ASA9A10

Time

1526-15351603-16211631-16511733-17451753-18101818-1825

Na’

2.511.3

Mg

0.77t0.391.0U0.68

(b) UW Fl

Al’

1.610.53.710.941.210.95

ight 1055

Si’

1.710.70l.OtO.581.410.443.1t0.712.5t0.721.2tl.O

on 24 July 1982

P

1.6t0.342.1*0.552.010.532.210.65

S

0.510.41.510.41.710.372.510.563.2t0.761.910.74

(Filter A3

C1’

11.72lU.460.8810.411.810.67

had Hi-’ 1

K

2.910.53.210.57.610.94.910.85.96t0.9

.710.55

Ca

6.510.7419.712.043.H4.417.4H.815.111.7

ug m-

Pb

Br’ was

Cr

0.3t0.250.3710.27

1.110.39

not detected

Mn

1.5t0.362.0t0.315.410.682.410.432.610.55

on remaining filters

Fe

5.6t0.65.710.654.810.557.910.908.610.975.310.72

Ni

0.47t0.20.33i0.10.5710.2

.)

Zn

0.4410.1810.7ll.l60.4510.220.64*0.28

Cu

0.26t0.15

Filter

Al(Amb)A2A3A4AllA12A13 1745-1754A14 1801-1824A15(Amb)1820-1824

Time

1557-16011612-16211633-16411650-165917101723-1735

Na+ Mg

4.2H.41.310.76

1.410.92

1.610.68

A!’

1.OtO.77

1.910.933.712.5

2.9H.O

Si’

0.7610.662.610.86

2.210.87

1.910.59

P

0.4610.34

1.310.881.610.595.3H.5

2.510.730.6810.500.7710.37

S

0.6110.401.510.64

1.810.69

1.510.82.910.611.210.610.9110.54

C1’

0.8610.541.710.94

2.1H.4

0.6210.52

K

1.H0.381.610.476.1H.14.910.726.411.42.410.727.210.921.910.490.7010.32

Ca

2.H0.342.210.4116.8H.817.611.912.5U.67.510.9916.9H.84.510.73

Pb

2.9H.1

6.712.2

0.5310.33

0.3410.28

Cr

0.4610.26

Mn

3.2*0.654.H0.642.010.762.010.503.410.520.7210.23

Fe

4.810.592.810.497.710.997.510.905.4H.O4.410.624.510.602.810.482.710.41

Ni

0.5910.251.410.400.4610.22

0.5H0.220.3710.23

Zn

15.6H.7

6.410.90

Cu

0.2310.16

Filter Time Ha Mg A1 Si

(c) UM Flight 1056 on 25 July 1982

s C^ K Ca Pb Cr Mn Fe Ni Zn CuA17A18

1.210.58 2.410.83 1.H0.52 1.010.54 0.8310.38 0.5810 281.810.88 1.410.65 1.310.77 2.610.68 1.H0.44 1.210.46

2.710.432.210.45

Na^!^"^^!^" S^l.^l^" ^’09; C^.O^T^O^ they are 10’- The correction factors are:

TABLE 6.3 Continued

(c) UU Flight 1056 on 25 July 1982 (Continued)Fnter T’"le Na+ "9 Al’ Si’ P S Cl’ K r---__________________________________________________ M" Fe N1 z" cuA19A20A21A23

2.311.9 3.411.8 2.711.0 2.8H.1 Q.O 7S0.92t0.45 n 77n ?;n o’5 5.2l0.98 1.8l0.60

^-^-^^ :: .-.--j;:;i(d) UW Flight 1057 on 26 July 1982 (No Cu measured on this flight.)Filter Time Na’ Mg A1’ Si’ p s Cl’ K r.cl K ca f>b Cr Mn Fe Ni Zn Br-A36A3A38A39A40

:: 2:9^5 2w90 :: :: ?:^423 :: 0-^0-JO ^^J/ 3oto85 o32t()26 37to46 ^0.451.8tl.6 2.210.85 5.3tl.7 5.2U.5 2t0 71 y’lin K3 2’2^’" 2.4*0.372.5tl.l ? o.o lo 410 49 3’Lo’54 M^’. ^56>05() 2.610.51 0.7210.35

1.310.87 1:0-0:82 2 0-54 ^^L l5to34 33to45 2.010.37 1.H0.33Ktn .4 .’., 3-3 0-64 3.510.67 0.7210.34 2.210.58

^ s..;;., "3’ i:f;;:;< ’:^^ -..... I.;;;.;; ^ ,.... :: ;.^ ^"""" ,,;,, ;::::;;:g :: ^J;iK^^^-’" l^ls H 2-"4 :-0-^^;:K!; ";"5 ;-0:"A47(no vol. given) ’-"^"" l./tU.Oi) 3.1tU.56 9.2tl.O 0.8910.33 1.H0.32 2.9+/-0.46 0.73+/-0.22(e) UW Flight 1060 on 15 September 1982 (No Cr or Cu measured on this flight.)Filter Time Na+ Mg A^ Si’ P S C^+ K rCl K Ca Pb v Mn Fe Ni Zn Br"

I1"1 ^^^Si: ?:;f S! Hi;js:r gjf ;:s^;i, |:%!L^:i!;: o""\!S^"w-5 l.^"."^ 4.211.2 4.110.76 1.610 48 4 5t0 71 3 ^0 2 I ’4 11 ^} R d;n 7S o25t()18 24+/-03Z 4lt()46 0.8H0.17 3.810.53s :-- ^^^ ;:;;s:i; 2:;;s:;; ^;^ iij:j !:;isi - j;sS:!s ^S "’:." ;;;^.^S

TABLE 6.3 Continued

,^ ^ ^ ^(e) UH;:^

106U " - ----- 1932 (. . o. .^ on .is ^t.) (confine------------____________________L cl K Ca p v Mn Fe Ni Zn Br-UW-8UM-9UW-10UM-11UW-12UH-13UU-14UW-15UM-16

i^iii ;;^:ls ISiHS^iiii ^T -^..i^pii^^...,i. :^ ,-SH "’"l ?^’ !.l;-^’S:S:^ 1:;^ ;:^ ;:^": ^ & . S S;; ..;.... !:^ j:i;S:Ii S:!!;S:?5 ^^ ii-"M