Page 1 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

Page 2 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Overview  Status of Validation  Validation results: SCIAMACHY: operational O 3 -columns with GOME NO 2 -columns operational and retrieved by IUP with GOME MIPAS:operational O 3- profiles with HALOE and SAGEII operational MIPAS H 2 O-profiles with HALOE SCIAMACHY: O 3- profiles retrieved by IUP with POAM III NO 2- profile retrieved by IUP with POAM III  Concluding remarks Results of the Bremen group on retrieving trace gases from uncalibrated level 0 (raw) limb and nadir level 1 SCIAMACHY data are still preliminary First validation results of MIPAS and SCIAMACHY trace gas products are still preliminary

Page 3 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 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 Bremen TOMS: 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 InstrumentData productGeometryEnvisat Instrument SAGEII (10/84) O 3 profiles NO 2 profiles H 2 O profiles occultationG,M,S* HALOE (9/91) O 3 profiles NO 2 profiles H 2 O profiles CH 4 profiles occultationG,M,S* only M,S POAM III O 3 profiles NO 2 profiles occultationonly S-IUP GOME (4/95) O 3 columns NO 2 columns O 3 profiles nadir TOMS (7/96) O 3 columnsnadir SABER (12/01) O 3 profiles H 2 O profiles limb ACE-FTS (12/02) O 3 profiles NO 2 profiles H 2 O profiles CH 4 profiles occultation (3/98) S

Page 4 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 SCIAMACHY and GOME DOAS O 3 and NO 2 products SCIAMACHY Version 3.53 and 4.0 equivalent to GOME 2.4: US standard atmosphere for NO 2 leads to un- derestimation of VCD under polluted conditions O 3 lv2-product:UV fit window nm VIS fit window nm NO 2 lv2-product:VIS fit window 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 NO 2 in the tropics through fitting of H 2 O and O 4 O 3 lv2-product:UV fit window nm no VIS product NO 2 lv2-product:VIS fit window nm Soon version 3.0: TOMS V7.0 climatology for O 3 and column-/latitude- classified AMF

Page 5 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of SCIAMACHY O 3 total columns (UV) with GOME All O 3 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 O 3 total column retrieval still very good despite degradation of scan mirror (~3%)

Page 6 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of O 3 total columns: (SCIA-GOME)/GOME SCIAMACHY (3.53) ozone columns (UV) about –5 % to GOME (2.7)

Page 7 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of O 3 total columns SCIAMACHY (3.53) O 3 total columns show –5 % to GOME (2.7)

Page 8 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 SCIAMACHY 4.0: Calibration orbits 2509 and 2510 Comparison of O 3 total columns Bad pixels already filtered out Retrieval of O 3 columns not better than 3.53

Page 9 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of SCIAMACHY O 3 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

Page 10 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of SCIAMACHY NO 2 total columns (VIS) with GOME Calibration orbits 2509 and 2510 version 4.0 IUP retrieval (A. Richter) GOME 2.7

Page 11 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of NO 2 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

Page 12 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of NO 2 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

Page 13 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of NO 2 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)

Page 14 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of MIPAS (4.53) O 3 profiles with HALOE (v19) High latitudes Southern Hemisphere 8.5 ) Number density VMR HALOE within 250 km of MIPAS measurements during the same day 57 collocations for most at 60°S - 90°S (32), only 3 in the tropics

Page 15 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of MIPAS (4.53) O 3 profiles with HALOE (v19) Tropics number density VMR.3 ) Accuracy of HALOE O 3 -Profiles: km 6% km 20%

Page 16 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of MIPAS (4.53) O 3 profiles with HALOE (v19) Mean deviation for km: MIPAS +10% – -15 % compared to HALOE (number density) +20% – -10%(VMR) km: MIPAS large deviation to HALOE

Page 17 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of MIPAS (4.53) O 3 profiles with SAGEII (6.1) Mean deviation for km: MIPAS +0% – -20 % compared to SAGEII (number density) +20% – -20%(VMR) km:- 35% – -10% (number density & VMR) km: MIPAS large deviation to SAGEII Accuracy of SAGEII O 3 -Profiles: km 10% But, some bad profiles with altitude error due to recent processing problems 76 collocations for Most at 60°S-90°S(20),60°N-90°N(32) only 16 in mid-latitudes, 8 in tropics

Page 18 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of MIPAS (4.53) H 2 O profiles with HALOE (v19) Mean deviation for >20-55 km: MIPAS +5% – +15 % compared to HALOE (VMR) km: MIPAS large deviation to HALOE Accuracy of HALOE H 2 O-Profiles: km15% km 25% 20 collocations for Most at 30°-60° (16), only 4 at 60°-90°

Page 19 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of IUP-SCIAMACHY O 3 profiles with POAM III Rozanov: Differential retrieval employing Chappuis bands Savigny: 3 wavelength retrieval employing O 3 Chappuis bands Preliminary results! d d d km O 3 vertical column: SCIAMACHY: 378 DU POAM III: 384 DU Total O 3 column: GOME:459 DU TOMS:456 DU SCIAMACHY at 56-59°N, ° :30 UTC POAM at 62°N, 253° :50 UTC

Page 20 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Comparison of IUP-SCIAMACHY NO 2 profiles with POAM III NO 2 was scaled to the POAM measurement and used as input to simulate the diurnal variation of the NO 2 vertical profile backward to SZA = 49 deg. (All model runs by M. von Koenig) IUP retrieval by A. Rozanov Preliminary results!

Page 21 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 Concluding Remarks (1) SCIAMACHY compared to GOME total O 3 columns (3.53 and 4.0) ~ - 5% NO 2 SCD (4.0) consistent offset NO 2 VCD (4.0) AMF problems –60%- 0%, but NO2 VCD (3.53) much worse Update to equivalent of GOME 3.0 (better climatology for NO 2 and O 3, iterative AMF) Comparison of GOME NO 2 data to ground based measurements SCIAMACHY O 3 and NO 2 profiles compared to POAMIII These preliminary results give confidence that good profile data can be retrieved from SCIAMACHY limb measurements

Page 22 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 MIPAS O 3 profiles (4.53) compared to HALOE km +/- 10 % for number dens., slight pos. bias for VMR compared to SAGEII km –35 - 0% for number dens., slight pos. bias for VMR MIPAS O 3 profiles look quite good, below 20 km improvements required comparisons of MIPAS temperature to HALOE (NCEP) temperature comparisons to SAGEII must sort out bad SAGEII profiles (error bars) MIPAS H 2 O profiles (4.53) compared to HALOE km % MIPAS H 2 O profiles look quite good, 55km improvements required Concluding Remarks (2)

Page 23 Validation by Model Assimilation and/or Satellite Intercomparison - ESRIN 9–13 December 2002 data quality of operational GOME NO2 not to good, data quality of GOME NO2 retrieved by the IUP (A. Richter) much better