a comparison of omi no 2 vtc with in- situ measurements in switzerland dominik brunner, brigitte...

Materials Science &Technology

A comparison of OMI NO2 VTC with in-situ measurements in Switzerland

Dominik Brunner, Brigitte Buchmann,Thomas Seitz, and Martin Steinbacher

Empa, Swiss Federal Laboratories for Materials Testing and Research Laboratory for Air Pollution and Environmental Technology

8600 Dübendorf, Switzerland

Thanks to Folkert Boersma and Ruud Dirksen (KNMI)for creating the post-analysis near-real time (PA-NRT) OMI data

and providing it through TEMIS

2Materials Science&Technology

50km N

Basel

BernChaumont

Davos

DübendorfHärkingen

Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Motivation The NABEL air quality monitoring network in Switzerland NOx and NO2 trends since 1980s

Measurements with conventional NOx sensors Lessons from parallel operation of molybdenum &

photolytic converters

Comparison with in situ NO2 measurements NO2(m) = NOx (molybdenum) - NO NO2(c ) = NO2(m) corrected for interferences

Comparison with ground-based NO2 columns Measurement stations and method used for computation

of columns Direct comparison with columns integrated over profile Comparison with averaging kernel weighted columns

Conclusions and outlook

Outline

Outline

Motivation NABEL NOx trends

NOx sensors

Comparisonin-situ NO2

NO2(m) NO2(c)

Comparisonto columns Method Direct Avg. kernel

Conclusions& Outlook


50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Urban, near street Rural < 1000 m amslUrban, in park Rural > 1000 m amslMotorway Prealpine, forestAgglomeration Alpine

Swiss Air Pollution Monitoring Network (NABEL)

Air Pollution/Environmental Technology

50kmN

Basel

Bern

Chaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

PayerneRigi

Sion

Tänikon

Zürich

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Assessment of Swiss Air Pollution Policy Swiss National Air Pollution Monitoring Network (NABEL)

sulphur dioxide (SO2)

nitrogen dioxide (NO2)

0

10

20

30

40

50

60

70

1980 1985 1990 1995 2000

µg

/m3 Limit value

NABEL measurement station Zurich downtowncity background

Additional reduction

measures needed

Air Pollution reduction measures successful

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

NO2 measurements using conventional NOx sensors with Molybdenum converters

PAN

Mean annual NOMean annual NO22 cycles cycles

rural pre-alpine

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

SC

IA

OM

I

~60% high inspring/summer

~20% high inautumn/winter

rural

pre-alpine

NO2 measurements using conventional NOx sensors with Molybdenum converters

Mean diurnal cyclesMean diurnal cycles

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

OMI NO2 VTCs vs. ground-based NO2Selection of OMI pixels for given NABEL measurement stationsSelection of OMI pixels for given NABEL measurement stations

Payerne (rural)

Tänikon (rural)

Dübendorf (sub-urban)

Swiss high-resolution NOx inventory

Zurich

Bern

Basel

Geneva

Swiss alps

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

OMI NO2 VTCs vs. ground-based NO2

Daily hourly mean 12-13 UTC (13-14 LT) values at Tänikon Daily hourly mean 12-13 UTC (13-14 LT) values at Tänikon used for comparison with OMIused for comparison with OMI

NO2(m), molybdenum converter

NO2(c), corrected (Steinbacher et al., 2007)

Clear sky according to both OMI and ground

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich


Fractional cloud cover of OMI pixels over TänikonFractional cloud cover of OMI pixels over Tänikon

Fractional cloud cover

Temperature at Tänikon

Points identified as clear sky basedon global radiation sensor at Tänikon

Snow cover

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

NO2(m)

Direct comparison with volume mixing ratios Direct comparison with volume mixing ratios measured in-situ at Tänikonmeasured in-situ at Tänikon


Corrected NO2(c)

NO2(c) [ppb]NO2(m) [ppb]

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Construction of vertical profiles and VTCs at Tänikon and PayerneConstruction of vertical profiles and VTCs at Tänikon and Payernefrom ground based observations at different altitudesfrom ground based observations at different altitudes

OMI NO2 VTCs vs. ground-based NO2 VTCs

50km

Chaumont

Jungfraujoch

Lägeren

PayerneRigi

TänikonCombination of measurements atTänikon 539 m amslLägeren 689 mRigi 1013 mChaumont 1137 mJungfraujoch 3650 m

NO2(m) at Tänikon vs. Lägeren NO2(m) at Chaumont vs. Rigi

r=0.89 r=0.75

Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Selected NOSelected NO22 profiles above Tänikon reconstructed profiles above Tänikon reconstructed

from ground-based corrected NOfrom ground-based corrected NO22(c) measurements(c) measurements


Outline


NOx sensors


NO2(m) NO2(c)



Winter (28. Jan 2006) Summer (18. Aug 2006)

TänikonLägeren

Rigi and Chaumont

Jungfraujoch


50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Direct comparison without using averaging kernelsDirect comparison without using averaging kernels


Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

Ground-based columns using averaging kernelsGround-based columns using averaging kernels(see Schaub et al., 2006)(see Schaub et al., 2006)


Outline


NOx sensors


NO2(m) NO2(c)




50km N

Basel

BernChaumont

Davos


Jungfraujoch

Lägeren

Lausanne

Lugano

Magadino

Payerne Rigi

Sion

TänikonZürich

NABEL in situ measurements from different stations at different elevations combined to construct vertical profiles

Conventional NOx measurements need correction

Comparison of OMI VTCs with in situ NO2 VMR shows reasonable to good agreement except for summer

No improvement when using corrected NO2(c)

Comparison of OMI VTCs with ground-based reconstructed VTCs shows better agreement than comparison with NO2 VMR

Using averaging kernels significantly improves agreementbetween OMI VTCs and reconstructed VTCs

Future: Use photolytic converter measurements at Payerne andRigi, extend data set to 2007, new OMI data version, try toassess uncertainty of ground-based columns

Summary and outlook

Outline


NOx sensors


NO2(m) NO2(c)



a comparison of omi no 2 vtc with in- situ measurements in switzerland dominik brunner, brigitte...

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