TOPSE: Tropospheric Ozone Production About the Spring Equinox Elliot Atlas & TOPSE Science Team.

TOPSE: Tropospheric Ozone Production

About the Spring Equinox

Elliot Atlas &

TOPSE Science Team

Primary Objective of TOPSE

To investigate the chemical and dynamic evolution of tropospheric chemical composition

over mid- to high-latitude continental North America during the winter/spring transition, with

particular emphasis on the springtime ozone maximum in the troposphere.

Measurement InvestigatorsRemote Ozone/Aerosols Browell et al., NASAAcidic Trace Gases/7-Be Talbot, Dibb, et al. UNHNMHC, Halocarbons, RONO2 Blake et al., UCINO2, Peroxynitrates Cohen, Thornton et al., UCBSpeciated Peroxides Heikes, Snow, URIOH, H2SO4 Eisele, Mauldin, NCARHO2, RO2 Cantrell, Stephens, NCARHNO3 Zondlo, NCARNOx, NOy, Ozone Ridley, Walega, NCARCH2O, H2O2 Fried, NCARJ values Shetter, Lefer et al., NCARPAN, PPN Flocke, Weinheimer, NCARCO, N2O Coffey, Hannigan, NCARUltrafine Aerosols Weber, GITMission Scientists/P.I.s Atlas, Cantrell, Ridley, NCAR

TOPSE Investigators: Measurements

Modeling/Collaboration InvestigatorsRegional/Forecast Model (HANK) Klonecki, Hess et al., NCARGlobal Model Analysis Tie, Emmons et al., NCAR

(MOZART) Brasseur et al., MPIProcess and Radiation Models Madronich, Stroud et al., NCARGlobal Model/Process Studies Jacob, Evans, Harvard U.Stratosphere/Troposphere Exch. Allen, Pickering, U. Md.Regional/other Models Wang et al., Rutgers U.Meteorological Forecast/ Moody, Cooper, Wimmers, U.Va.

Remote SensingOzonesonde Network Merrill, URI; Fast, PNWL

GOME BrO Richter, Burrows, U. BremenMet. Forecasts (UT/LS) Newman, NASAPolar Sunrise Expt., 2000 Shepson, Purdue;

Bottenheim, Can. Met. Serv.

TOPSE Investigators: Modeling/Collaboration

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Latit

ude

-140 -120 -100 -80 -60 -40 -20

Longitude

Denver

Winnipeg

Churchill

Thule

Alert

TOPSE Flight Tracks: Feb - May, 2000

1 2 3 4 5 6 7

Deployment Number

TOPSE Flight Tracks

• Seasonal variation in trace gases/aerosols• Evolution strong function of altitude and latitude• Decline in NMHC; Spring maximum in sulfate• PAN most significant odd-nitrogen component of NOy

• Ozone evolution in the mid-troposphere• Increase about 20 ppb from Feb-May• Covariation in PANs, aerosols; no PV trend• Photochemical/surface sources implicated

• Surface ozone depletion• Observations in early spring-May• Br-catalyzed ozone loss• Long-range transport of depleted air suggested

• Transport processes• Most sampled air masses representative of

background mid-troposphere• Distant pollution sources were encountered in layers

Some TOPSE Highlights

•In-situ photochemical processes• Measured radicals consistent with constrained

models• Hydrogen peroxide 2 – 10 x lower than model• Formaldehyde photolysis significant HOX source

at high latitudes• Calculated increase in in-situ ozone production in

spring from increasing HOX sources and NO

• Stratosphere-troposphere exchange• Remote sensing (satellite/lidar) indicate

folds/streamers/STE(?)• In-situ encounters with lower stratosphere during

flights• 7-Be measurements/models suggest significant

fraction of tropospheric ozone is from stratosphere. Seasonal modulation by photochemistry with contribution by STE

Some TOPSE Highlights (cont’d)

Seasonal evolution of NMHC vs. latitude and altitude during TOPSE

(Blake et al., UCI)

8000

7000

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0

Pal

t m

102 4 6 8

1002 4 6 8

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[CH2O] pptv

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1002 4 6 8

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[CH2O] pptv

102 4 6 8

1002 4 6 8

1000

[CH2O] pptv

40 to 50 N Lat

All Meas Median Meas in Alt Bin Median Model in Alt Bin

50 to 57 N Lat > 57 N Lat

Figure 1

(Fried et al. – NCAR)

Formaldehyde vertical distributions vs. latitude:Feb – May, 2000

TOPSE SULFATE MIXING RATIO GEOMETRIC MEAN ALTITUDE PROFILE

(Latitudes 58oN to 85oN)

Aerosol sulfate mixing ratio (pptv)

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ssu

re A

ltitu

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(m

ete

rs)

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1988 GTE/ABLE 3A Summertime SO42- Averages

(Scheuer, Talbot, Dibb – UNH)

Evolution of Sulfate Aerosol Vertical Distribution

1 – 7 = Deployment number (Feb – May)

6000

4000

2000

0

Pre

ssur

e A

ltitu

de (

m)

250200150100500Ozone (ppbv)

140

120

100

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40

Day of Y

ear

(Ridley, Walega - NCAR)

Ozone vertical profile: Evolution during winter-spring

BR_O3

52.315 53.8957.04

59.63562.86 63.065

74.61

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100

0 1 2 3 4 5 6 7 8

Mission

Deployment 1 Deployment 3

Deployment 6Deployment 5

Deployment 4

Deployment 7

Average Ozone Distributions During TOPSE(Browell et al., NASA)

40 60 80 100 120 140 16050

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2 km > altitude < 6 kmlatitude > 50 N

TOPSE: Average Trends in O3 and PANs

PANs

PA

Ns

(ppt

)

Day of Year

45

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85

90O

3 (ppb)

O3

(Cohen, Thornton – UCB Flocke, Ridley – NCAR)

PANs and ozone in the mid-troposphere

(Dibb et al., UNH)

7Be measurements diagnose stratospheric O3

7Be/O3 correlation during TOPSE

Observations of stratospheric influence: 7Be, HNO3, O3

Chemical Transport Models (Global and Regional)

Significant Model Differences:MOZART HANK

Domain Global North of 20o

Hor. Resolution 2o x 1.9o 243 km (Mercator proj.)

Vert. Resolution 60 layers to 0.1 hPa 38 layers to 100 hPa

Meteorology ECMWF MM5 (NCEP)

Stratospheric O3 Climatological Relaxed to P.V.

Model Similarities: Chemical Mechanisms, Emissions, Dry Deposition, Washout, Lightning

(Emmons, Hess, et al. – NCAR)

Average of O3 for all flights

All TOPSE flights: 40-85N, 235-300E, Surface to 350 hPa

Good agreement between models and data until May

O3 Budget: 30o-90o North, Surface-350 hPa MOZART, HANK

PRODUCTION:

HO2+NO->NO2+OH

RO2+NO->NO2+RO

DESTRUCTION:

HO2+O3->OH+2O2

OH+O3->HO2+O2

H2O+O(1D)->2OH

O3 Production and Loss Rates: 40-60NComparison with Steady-State Model constrained by TOPSE

observations (Cantrell)

MOZART

HANK

SS-Model

Prod.

Loss

ODE

DIAL observations of surface ozone depletion over Hudson Bay

(Browell et al. – NASA)

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0

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ssur

e A

ltitu

de (

m)

72x103

717069686766Midtime (secs after midnight)

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0

Ozo

ne (

ppbv

) an

d S

olub

le B

rom

ide

(ppt

v)

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100

0

Ethyne (pptv)

Pressure Altitude (m) Ozone (ppbv) Ethyne (pptv) SolubleBromide (pptv)

TOPSE - HUDSON BAY : Low Ozone Transect

(Ridley-NCAR; Blake-UCI; Talbot-UNH)

In-situ measurements over Hudson Bay:Observations of surface ozone depletion

Transport of ozone depleted surface air from Arctic to Hudson Bay:

Evidence from measurements, models, satellite

SummaryTOPSE characterized seasonal evolution of ozone and precursors over continental N.America

Seasonal and altitude dependent transport Siberia/Europe vs. Asia

Ozone background has strong stratospheric source, but growth in spring is primarily from in-situ chemistry in troposphere

O3/aerosol/precursor relationships7Be analysis/models(Surface ozone depletion widespread

in Arctic…transport significant)

Models capture many features of seasonal change after improvements from measurement comparison, but questions remain.

Hydrogen peroxideFormaldehyde in UTetc….

TOPSE Science Team

Engineers, technicians, staff and pilots of NCAR Research Aviation Facility

Ground support at Churchill Airport and Thule Air Base

Financial support of the National Science Foundation Atmospheric Chemistry Polar Programs NCAR Directors Fund

Administrative and logistical support of the Atmospheric Chemistry Division, Traffic Services

Acknowledgments