Bojan R. Bojkov et al.

[email protected] http://fmiarc.fmi.fi/SAUNA/Atmospheric Science Conference

8-12 May, 2006 - ESA ESRIN Frascati

Bojan R. Bojkov et al.NASA GSFC/SSAI



Outline• Background of SAUNA total ozone intercomparison

• Campaign overview» Host facilities» Participants» Instrumentation» March/April 2006

• Preliminary results» Groundbased data» Satellite TOZ comparison



Background

• Most groundbased total ozone intercomparisons are performed at mid-latitude and column amounts of ~300DU» Agreement is usually of the order of about 3%

• Instrument-instrument performance show significant differences under conditions of low-sun and high ozone column amounts» ~5% differences, up to 10% in winter

• Satellite-groundbased differences 5-10% under these conditions» Satellite performance thought to be good to SZA ~80o

• Satellite-satellite differences of the order of 5-10% persist



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DeltaD104-BR010oriDeltaTeffCorr_newDeltaTeff_newMueCorrLinear (DeltaD104-BR10ori)Linear (DeltaTeff_newMueCorr)

Courtesy: U. Koehler (DWD)

Groundbased differences• Comparison of extremely well calibrated instruments, such as the 22 year

Dobson-Brewer record at Hohenpeissenberg

• Diff. within 3%

• After effectiveheight and Tcorrections,diff. <2%



ESA, 2002

Satellite differences

• GOME GDOAS vs. EP-TOMS V8 for 1997

• Differences of +/- 3% for midlatitudes, particularly duringlate-Fall and Winter

• 5-8% differences at high lat.,for high SZA and high TOZ

• Different crossing times:» ERS-2 ~10:00 desc.» EP ~ 12:00 asc.



Driving issue:

• Why do total column ozone measurements from groundbased and satellite instruments and their respective retrieval algorithms continue to differ at mid and high latitudes, and where large solar zenith angles and high total ozone amounts are typical?



SAUNA campaign• Organized by NASA, FMI and ESA

» Follow on to the 2001 TOMS3F campaign in Alaska

• Hosted by the Finnish MeteorologicalInstitute Arctic Research Center atSodankyla, Finland

• FMI-ARC is a fully operational long-term site» 20 year grounbased and balloons ozone records» Ancillary data collections» Satellite receiving station (Aura OMI VFD)

• ~120km north of Arctic circle(67.37N, 26.63E)

• Boreal climate, Arctic atmosphere



Campaign participants

• 30+ Scientists from 10 Institutions and 9 Countries:NASA-GSFC (USA), FMI-ARC (Finland), ESA-ESRIN (Italy),BIRA-IASB (Belgium), CNRS-SA (France), DWD-MOHp (Germany),INM-Izana (Spain), KNMI (Netherlands), MSC (Canada),NOAA-ERL-GMD (USA)

• Funding/Sponsors:» NASA-HQ, FMI, and ESA» EOS-Aura Project Science Office» National contributions from Canada, France and Spain



NASA GSFC (USA)A. Cede/R. McPetersBrewer: double

NASA-GSFC (USA)T. McGeeSTROZ-Lite LIDAR (NDSC standard)

DWD-MOHp (Germany)U. KoehlerDobson (European standard)

FMI-ARC (Finland)NASA-GSFC (USA)KNMI (Netherlands)

R. KiviB.R. BojkovE. Brinksma

Ozonesondes

CNRS-SA (France)F. GoutailSAOZ (permanently located at FMI-ARC)

BIRA-IASB (Belgium)M. van RoozendaelDOASs: 1 UV, 1 vis, 1 miniDOAS

INM-Izana (Spain)A. Redondas/E. CuevasBrewer: 1 double (European Standard)

MSC (Canada)T. McElroyBrewer: 1 single (World standard), 1 double

KNMI (Netherlands)E. BrinksmaminiDOAS

NOAA-ERL/GMD (USA)R. EvansDobson (Traveling standard)

FMI-ARC (Finland)E. KyröBrewer (single monochromator at FMI-ARC)

AffiliationPrincipal InvestigatorInstrument

Campaign instruments



FMI-ARC facilitiesduring SAUNA

Tower with miniDOASs

NASA LIDAR

Sounding station

Dobsons

Campaign instruments



March 26-April 13, 2006

• March/April did provide:» Total ozone columns in the

range 400DU to ~520DU» High variability/strong gradients» 12-16 hour measurement days» Minimum solar zenith angle of

65 degrees» 75% clear sky (12 of 18 good

days!)

• Up to 3 overpasses for swath instruments

250 300 350 400 450 500 550

X

OMI ozoneMarch 26, 2006



Brewers

• ~100 coincident (<30s) clear day 5 instrument measurements» Measurement range: 400-520DU» Slant column range: 900-2200DU» 0.5% accuracy and 0.3% precision (combined dataset)

• Result: stray light corrections for single Brewers» Single shows ~1% error at 1000DU slant column and ~5% error at

2000DU» Correction for measurements when slant column > 900DU» Useful for satellite validation

Photo: E. Brinksma, KNMI



Brewers: March 30 ‘06

“differences” attributed to stray light of single Brewers

T. McElroy and V. Savastiouk, MSC



Dobsons results

• Measurements:» 3 very good days, 3 decent days and 6 partial days» More data than seen than at most Dobson intercomparisons

• Achieved all high-latitude measurements goals» Extended schedules» AD, CD, CDFI pairs, plus zenith sky

• Two Dobsons in good agreement throughout campaign» AD pair is ~2.9% below Brewers» CD pair ~2.5% below Brewers



R. Evans, NOAA



Ozonesondes• 30 soundings (+ ~5 additional to early May):

» Coincident with Aura and Envisat instrument overpasses» 27 single instrument soundings» 2 double sounding with agreement better than 2% in stratosphere» 1 ozonesonde + NOAA CFH sounding

• 34.3 km average burst height

• 426.7DU < TOZ < 500.8DU

• <2% groundbased column agreement



Ozone layer variability

Ozon

e Par

tial P

ress

ure [

mPa

]

mid-lat. intrusion

Trop. foldingT. Turunen, FMI



SAOZ-DOAS(vis)

• Daily twilight measurements by both instruments types» Zenith-sky observations » All weather measurement capability

• Different optical path as Dobson/Brewer:» Due to measurement time differences» Measurement is at a different geolocation than instrument (up to

600km away)» Time/geolocation very for comparison, especially when large

gradients present

• Retrievals and intercomparisons ongoing



LIDAR• Measurements:

» 4 full nights (3/28, 3/29, 3/30 and 4/7), 2 partial night (4/2, 4/10)

• Satellite coincidences (to be investigated)» 4 Aura overpasses including 2 TES SO (3/29, 3/31)» 5 HIRLDS coincidences (late evening)

• Ozonesonde coincidences» 2 single (3/29, 3/31) and 1 double sounding (4/7)

• Data is being evaluated» GSFC LIDAR team on deployment since January 28 ‘06



Satellite comparisons

• Satellite products by FMI, BIRA-IASB, KNMI, NASA» Total column and profiles

• Initial comparisons of:» Groundbased vs. OMTO3, OMDOA3, SDOAS, TOSOMI» Investigations of clouds, reflectivity, SZA, TOZ effects

• Very preliminary!



Preliminary TOZ comparisonsOMI TOMS, OMI DOAS and SDOAS

Typical results during SAUNA

Comparison for the Aura period

(OMI DOAS and SDOAS are provisionally released data)



Satellite profile comparisons

• Comparison to be performed with LIDAR and sonde data

• 4 AURA instr.» Focus on TES

and HIRDLS

• ENVISAT» GOMOS, MIPAS

and Sciamachy

• NOAA SBUV/2s

G. Osterman, JPL



Conclusions

• Exceptional efforts and organization by all SAUNA teams, and in particular the local hosts at FMI-ARC

• Very interesting preliminary results» Single Brewer stray-light correction» Spatial (optical path) considerations» Groundbased and satellite algorithm differences

• Continued investigations required prior to SAUNA workshop atTenerife (October 2006)



Participants, Contributors and Co-authors

• NASA GSFC» B. Bojkov, R. McPeters, A. Cede,

D. Haffner, J. Herman, T. McGee,D. Silbert, G. Sumnicht, M. Yan

• FMI» E. Kyro, R. Kivi, O. Aulamo,

P. Heikkinen, J. Kahru, T. Koskela• ESA

» C. Zehner• BIRA-IASB

» M. van Roozendael, C. Fayt,C. Hermanns, J.-C. Lambert,G. Pinnardi

• CNRS-SA» F. Goutail, D. Ionov

• DWD-MOHp» U. Koehler, B. Hassler

• INM-Izana» A. Redondas, E. Cuevas,

C. Guirado, C. Torres• KNMI

» E. Brinksma• MSC

» T. McElroy, V. Savastiouk,D. Tarasick

• NASA-JPL» G. Ostermann

• NOAA ERL GMD» R. Evans, B. Walsh

Photo: F. Goutail

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Bojan R. Bojkov et al.

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