1 / 23

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

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. Overview

reuben
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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

  2. Overview • Status of Validation • Validation results: • SCIAMACHY: operational O3-columns with GOME • NO2-columns operational and retrieved by IUP with GOME • MIPAS: operational O3-profiles with HALOE and SAGEII • operational MIPAS H2O-profiles with HALOE • SCIAMACHY: O3-profiles retrieved by IUP with POAM III • NO2-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

  3. Instrument Data product Geometry Envisat Instrument SAGEII (10/84) O3 profiles NO2 profiles H2O profiles occultation G,M,S* HALOE (9/91) O3 profiles NO2 profiles H2O profiles CH4 profiles occultation G,M,S* only M,S POAM III O3 profiles NO2 profiles occultation only S-IUP GOME (4/95) O3 columns NO2 columns O3 profiles nadir TOMS (7/96) O3 columns nadir SABER (12/01) O3 profiles H2O profiles limb ACE-FTS (12/02) O3 profiles NO2 profiles H2O profiles CH4 profiles occultation 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 (3/98) S

  4. SCIAMACHY and GOME DOAS O3 and NO2 products GOME Version 2.7 with improvements for NO2 in the tropics through fitting of H2O and O4 O3lv2-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 for O3 and column-/latitude- classified AMF • 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 • O3lv2-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

  5. 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 totalcolumn retrieval still very good despite degradation of scan mirror (~3%)

  6. Comparison of O3 total columns: (SCIA-GOME)/GOME SCIAMACHY (3.53) ozone columns (UV) about –5 % to GOME (2.7)

  7. Comparison of O3 total columns SCIAMACHY (3.53) O3 total columns show –5 % to GOME (2.7)

  8. SCIAMACHY 4.0: Calibration orbits 2509 and 2510 Comparison of O3 total columns Bad pixels already filtered out Retrieval of O3 columns not better than 3.53

  9. Comparison of SCIAMACHY O3 totalcolumns (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

  10. Comparison of SCIAMACHY NO2 total columns (VIS) with GOME Calibration orbits 2509 and 2510 version 4.0 IUP retrieval (A. Richter) GOME 2.7

  11. Comparison of NO2 total columns: (SCIA-GOME)/GOME version 4.0 IUP retrieval (A. Richter) • strong variation with latitude: • –60% at 70°S to 0% at 70°N • stable offset of –20%, • <-60° down to –40%

  12. Comparison of NO2 slant columns: (SCIA-GOME)/GOME IUP retrieval (A. Richter) version 4.0 • both retrievals show offset of –10% with strong scatter for SCIAMACHY • largest contribution to total column error of operational product from AMF

  13. Comparison of NO2 total columns: (SCIA-GOME)/GOME IUP retrieval (A. Richter) version 3.53 • 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

  14. Comparison of MIPAS (4.53) O3 profiles with HALOE (v19) High latitudes Southern Hemisphere Number density VMR 8.5) 8.5) HALOE within 250 km of MIPAS measurements during the same day 57 collocations for 17.9.-21.10.2002 most at 60°S - 90°S (32), only 3 in the tropics

  15. 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%

  16. 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

  17. Comparison of MIPAS (4.53) O3 profiles with SAGEII (6.1) 76 collocations for 17.9.-31.10.2002 Most at 60°S-90°S(20),60°N-90°N(32) only 16 in mid-latitudes, 8 in tropics Accuracy of SAGEII O3-Profiles: 10-50 km 10% But, some bad profiles with altitude error due to recent processing problems 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

  18. Comparison of MIPAS (4.53) H2O profiles with HALOE (v19) 20 collocations for 17.9.-21.10.2002 Most at 30°-60° (16), only 4 at 60°-90° Accuracy of HALOE H2O-Profiles: 30-50 km15% 10-30 km 25% Mean deviation for >20-55 km: MIPAS +5% – +15 % compared to HALOE (VMR) 13-20 km: MIPAS large deviation to HALOE

  19. Comparison of IUP-SCIAMACHY O3profiles with POAM III Rozanov: Differential retrieval employing Chappuis bands Savigny: 3 wavelength retrieval employing O3 Chappuis bands d d d 10-40 km O3 vertical column: SCIAMACHY: 378 DU POAM III: 384 DU Total O3 column: GOME: 459 DU TOMS: 456 DU Preliminary results! SCIAMACHY at 56-59°N,238-253° 25.4.2002 18:30 UTC POAM at 62°N, 253° 25.4.2002 2:50 UTC

  20. Comparison of IUP-SCIAMACHY NO2 profiles with POAM III NO2 wasscaled to the POAM measurement and used as input to simulate thediurnal variation of the NO2 vertical profile backward to SZA = 49 deg. (All model runs by M. von Koenig) IUP retrieval by A. Rozanov Preliminary results!

  21. 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 POAMIII These preliminary results give confidence that good profile data can be retrieved from SCIAMACHY limb measurements

  22. Concluding Remarks (2) • 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 required • comparisons of MIPAS temperature to HALOE (NCEP) temperature • comparisons 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

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

More Related