a. bracher, m. weber, k. bramstedt, m. v. könig, a. richter, a. rozanov, c. v. savigny,

Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002

Validation of ENVISAT trace gas data products by comparison with GOME/ERS-2 and other

satellite sensors

A. Bracher, M. Weber, K. Bramstedt, M. v. König, A. Richter, A. Rozanov, C. v. Savigny, J. P. Burrows

Institute of Environmental Physics, University of Bremen


OverviewStatus of ValidationValidation results: SCIAMACHY: operational O3-columns with GOME

NO2-columns operational and retrieved by IUP with GOMEMIPAS: operational O3-profiles with HALOE and SAGEII

operational MIPAS H2O-profiles with HALOESCIAMACHY: O3-profiles retrieved by IUP with POAM III

NO2-profile retrieved by IUP with POAM IIIConcluding remarks

Results of the Bremen group on retrieving trace gases from uncalibrated level 0 (raw) limb and nadir level 1 SCIAMACHY data are still preliminaryFirst validation results of MIPAS and SCIAMACHY trace gas products are still preliminary


Satellite Instruments for Validation of GOMOS,MIPAS & SCIAMACHY

Cooperations:

SAGE II : L. Thomason (NASA LaRC) HALOE, SABER: J.M. Russell III, E.

Thompson (Hampton Univ.)POAM III: R. Bevilacqua (ONR, CNES,

NRL)GOME: IUP BremenTOMS: E. Hilsenrath, R. Mc Peters

(NASA GSFC) ACE-FTS: P. Bernath, K. Walker

(Univ. of Waterloo)

green: first validation* = only SCIA profiles retrieved by IUP blue: new instruments

Instrument Data product Geometry EnvisatInstrument

SAGEII(10/84)

O3 profilesNO2 profilesH2O profiles

occultation G,M,S*

HALOE(9/91)

O3 profilesNO2 profilesH2O profilesCH4 profiles

occultation G,M,S*

only M,SPOAM III

O3 profilesNO2 profiles

occultation only S-IUP

GOME(4/95)

O3 columnsNO2 columnsO3 profiles

nadir

TOMS(7/96)

O3 columns nadir

SABER(12/01)

O3 profilesH2O profiles

limb

ACE-FTS(12/02)

O3 profilesNO2 profilesH2O profilesCH4 profiles

occultation

(3/98)

S


SCIAMACHY and GOME DOAS O3 and NO2 products

SCIAMACHY

Version 3.53 and 4.0 equivalent to GOME 2.4:US standard atmosphere for NO2 leads to un-derestimation of VCD under polluted conditions

O3 lv2-product: UV fit window 325-335 nm VIS fit window 425-450 nm

NO2 lv2-product: VIS fit window 425-450 nm

Lv-1 product for 4.0 better than 3.53:•new SCIAMACHY sun spectrum•polarisation correction•different spectral calibration•different dark current

GOME

Version 2.7 with improvements for NO2 in thetropics through fitting of H2O and O4

O3 lv2-product: UV fit window 325-335 nm no VIS product

NO2 lv2-product: VIS fit window 425-450 nm

Soon version 3.0: TOMS V7.0 climatology forO3 and column-/latitude- classified AMF


Comparison of SCIAMACHY O3 total columns (UV) with GOME

• All O3 data of time period in 2.5° X 2.5° grids• Bad SCIA pixels (low/no light) filtered out • Comparison of SCIAMACHY (3.53) and GOME (2.7) data within the same grid• GOME O3 total column retrieval still very good despite degradation of scan mirror (~3%)


Comparison of O3 total columns: (SCIA-GOME)/GOME

SCIAMACHY (3.53) ozone columns (UV) about –5 % to GOME (2.7)


Comparison of O3 total columns

SCIAMACHY (3.53) O3 total columns show –5 % to GOME (2.7)


SCIAMACHY 4.0: Calibration orbits 2509 and 2510 Comparison of O3 total columns

Bad pixels already filtered outRetrieval of O3 columns not better than 3.53


Comparison of SCIAMACHY O3 total columns (VIS) with GOME (UV)

SCIAMACHY (3.53) SCIAMACHY (4.0)

SCIAMACHY 3.53 very bad (up to 200% difference to GOME)SCIAMACHY 4.0 much better, but still very big scatter


Comparison of SCIAMACHY NO2 total columns (VIS) with GOMECalibration orbits 2509 and 2510

version 4.0

IUP retrieval (A. Richter)

GOME 2.7


Comparison of NO2 total columns: (SCIA-GOME)/GOME

version 4.0 IUP retrieval (A. Richter)

• stable offset of –20%, •<-60° down to –40%

•strong variation with latitude: –60% at 70°S to 0% at 70°N


Comparison of NO2 slant columns: (SCIA-GOME)/GOME

• both retrievals show offset of –10% with strong scatter for SCIAMACHY largest contribution to total column error of operational product from AMF

IUP retrieval (A. Richter)

version 4.0


Comparison of NO2 total columns: (SCIA-GOME)/GOME

•much worse than version 4.0 (there in lv1 data: better polarisation correction, sun spectrum) •strong variation with latitude:

–50% at 70°S to +140% at 70°N

• variation from 0% at high latitudes to +50% in the tropics•no sun spectrum used, fitted against SCIA spectrum in the tropical Pacific

version 3.53 IUP retrieval (A. Richter)


Comparison of MIPAS (4.53) O3 profiles with HALOE (v19)High latitudes Southern Hemisphere

8.5) 8.5)

Number density VMR

HALOE within 250 km of MIPASmeasurements during the same day

57 collocations for 17.9.-21.10.2002most at 60°S - 90°S (32), only 3 in the tropics


Comparison of MIPAS (4.53) O3 profiles with HALOE (v19)Tropics

number density VMR.3) .3)

Accuracy of HALOE O3-Profiles: 30-60 km 6% 15-30 km 20%


Comparison of MIPAS (4.53) O3 profiles with HALOE (v19)

Mean deviation for 20-60 km: MIPAS +10% – -15 % compared to HALOE (number density) +20% – -10% (VMR)

13-20 km: MIPAS large deviation to HALOE


Comparison of MIPAS (4.53) O3 profiles with SAGEII (6.1)

Mean deviation for 20-35 km: MIPAS +0% – -20 % compared to SAGEII (number density)+20% – -20% (VMR)

35-60 km: - 35% – -10% (number density & VMR) 13-20 km: MIPAS large deviation to SAGEII

Accuracy of SAGEII O3-Profiles: 10-50 km 10%But, some bad profiles with altitude error due to recent processing problems

76 collocations for 17.9.-31.10.2002Most at 60°S-90°S(20),60°N-90°N(32)only 16 in mid-latitudes, 8 in tropics


Comparison of MIPAS (4.53) H2O profiles with HALOE (v19)

Mean deviation for >20-55 km: MIPAS +5% – +15 % compared to HALOE (VMR) 13-20 km: MIPAS large deviation to HALOE

Accuracy of HALOE H2O-Profiles: 30-50 km15% 10-30 km 25%

20 collocations for 17.9.-21.10.2002Most at 30°-60° (16), only 4 at 60°-90°


10

20

30

40

50

0 1x1012 2x1012 3x1012 4x1012 5x1012 6x1012 7x1012

10 - 40 km O3 columns:

SCIAMACHY: 378 DUPOAM III: 384 DU

Total O3 column:

GOME: 459 DUTOMS: 456 DU

SCIAMACHY - POAM III coincidence on April 25, 2002

SCIA, Rozanov Lat: 56o-59o N, Long: 238o-253o, 18:30 UTC SCIA, Savigny Lat: 56o-59o N, Long: 238o-253o, 18:30 UTC POAM, Lat: 62o N, Long: 253o, 2:50 UTC

O3 density [cm -3]

Alti

tude

[km

]

Comparison of IUP-SCIAMACHY O3profiles with POAM IIIRozanov: Differential retrieval employing Chappuis bands

Savigny: 3 wavelength retrieval employing O3 Chappuis bands

Preliminary results!

d

dd

10-40 km O3 vertical column:SCIAMACHY: 378 DUPOAM III: 384 DU

Total O3 column:GOME: 459 DUTOMS: 456 DU

SCIAMACHY at 56-59°N,238-253° 25.4.2002 18:30 UTCPOAM at 62°N, 253° 25.4.2002 2:50 UTC


Comparison of IUP-SCIAMACHY NO2 profiles with POAM III

NO2 was scaled to the POAM

measurement and used as input to simulate the diurnal variation of

the NO2 vertical profile backward

to SZA = 49 deg.(All model runs by M. von Koenig)

IUP retrieval byA. Rozanov Preliminary results!


Concluding Remarks (1)

SCIAMACHY compared to GOME•total O3 columns (3.53 and 4.0) ~ - 5% •NO2 SCD (4.0) consistent offset•NO2 VCD (4.0) AMF problems –60%- 0%, but NO2 VCD (3.53) much worse

Update to equivalent of GOME 3.0 (better climatology for NO2 and O3, iterative AMF)Comparison of GOME NO2 data to ground based measurements

SCIAMACHY O3 and NO2 profiles compared to POAMIIIThese preliminary results give confidence that good profile data can be retrieved fromSCIAMACHY limb measurements


MIPAS O3 profiles (4.53)•compared to HALOE 20-60 km +/- 10 % for number dens., slight pos. bias for VMR•compared to SAGEII 20-60 km –35 - 0% for number dens., slight pos. bias for VMR

MIPAS O3 profiles look quite good, below 20 km improvements requiredcomparisons of MIPAS temperature to HALOE (NCEP) temperaturecomparisons to SAGEII must sort out bad SAGEII profiles (error bars)

MIPAS H2O profiles (4.53)•compared to HALOE 20-55 km +5 - +15 %

MIPAS H2O profiles look quite good, <20 km and > 55km improvements required

Concluding Remarks (2)


data quality of operational GOME NO2 not to good, data quality of GOME NO2 retrieved by the IUP (A. Richter) much better

a. bracher, m. weber, k. bramstedt, m. v. könig, a. richter, a. rozanov, c. v. savigny,

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