1 / 53

PARAMETERS to be retrieved: 1. Cloud optical thickness /5-100/ 2. Cloud top height /0.5-10km/

SEMIANALYTICAL CLOUD RETRIEVAL ALGORITHM AND ITS APPLICATION TO DATA FROM MULTIPLE OPTICAL INSTRUMENTS ON SPACEBORNE PLATFORMS: SCIAMACHY, MERIS, MODIS, SeaWiFS AND GOME Alexander A. Kokhanovsky, Vladimir V. Rozanov Wolfgang von Hoyningen-Huene, John P. Burrows

ira
Download Presentation

PARAMETERS to be retrieved: 1. Cloud optical thickness /5-100/ 2. Cloud top height /0.5-10km/

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. SEMIANALYTICAL CLOUD RETRIEVAL ALGORITHM AND ITS APPLICATION TO DATA FROM MULTIPLE OPTICAL INSTRUMENTS ON SPACEBORNE PLATFORMS: SCIAMACHY, MERIS, MODIS, SeaWiFS AND GOME Alexander A. Kokhanovsky, Vladimir V. Rozanov Wolfgang von Hoyningen-Huene, John P. Burrows Institute of Remote Sensing, Bremen University P. O. Box 330440 Bremen, Germany alexk@iup.physik.uni-bremen.de

  2. PARAMETERS to be retrieved: 1. Cloud optical thickness /5-100/ 2. Cloud top height /0.5-10km/ 3. Cloud cover /0-1/ 4. Cloud albedo/0.3-0.8/ 5. Liquid water path /50-200 / 6. Thermodynamic phase /ice, water or mixed clouds/ 7. Average size of droplets/crystals

  3. PHYSICAL BASIS • Bi-spectral measurement of TOA reflectance to get cloud optical thickness (visible), cloud droplet radius (IR) • Spectrally resolved measurements (approximately, 50 spectral points in the oxygen A-band 758-772nm) to get CTH, CBH • The ratio R(1550)/R(1670) for the ice/water cloud discrimination

  4. 650nm

  5. 1550nm

  6. 758-770nm

  7. 1550nm/1670nm

  8. ALGORITHM Exponential approximation

  9. Table 1. Characteristics of selected space instruments, related to measurements of the backscattered light in the oxygen A-band (7550-7750 ). Instrument Platform Year Spectral interval, Spectral resolution, Spatial resolution, km2 GOME ERS-2 1995 5760-7940 3.3 40*320 SCIAMACHY ENVISAT 2002 6040-8050 4.8 30*60 MERIS ENVISAT 2002 7600 25 0.3*0.3 or 1.1*1.1 GLI ADEOS-II 2002 7630 80 0.25*0.25 and 1.0*1.0 POLDER ADEOS-II 2002 7633 7651 100 400 6.0*7.0

  10. Cloud top height determination from SCIAMACHY Typical SCIAMACHY spectra in the oxygen A-band

  11. 16.09.2004 WWW.IUP.PHYSIK.UNI-BREMEN.DE

  12. SeaWiFS

  13. VALIDATION MULTIPLE TECHNIQUES

  14. 1. NADIR LIMB 1050nm/750nm

  15. 6KM 2. RADAR

  16. Cloud top height determination from GOME data using oxygen A-band information as compared to ATSR-2 IR retrievals (ERS-2 satellite) 3. GOME FRESCO: TOO LOW CLOUDS

  17. 442nm 4. MERIS

  18. 5. MODIS: effective radius MODIS MODIS SACURA GLI 3750nm 1640nm

  19. CHARLEY, 12.08.2004, 15:50 CUBA TERRA 15 people killed 14 billion USD

  20. CONCLUSION • SACURA has great potentials in cloud remote sensing

  21. AcknowledgementsK. Bramstedt, M. BuchwitzR. de Beek, K.-U. EichmannW. Lotz, T. Nauss S. Noel, A. Rozanov H. Schroeter, M. VountasEuropean Space Agency DLR(grant 50EE0027)and NASA

  22. The retrieval techniques 1: The look-up-table approach cloud surface

  23. 2: The semi-analytical approach

  24. Optical characteristics of clouds Trishchenko and Liu, 2001 Kokhanovsky, 2003 ISCCP data Surface observations Number of cases Optical thickness

  25. The physics behind the semi-analytical approach Sun Satellite 1 2

  26. The cloud optical thickness determination

  27. The accuracy of the semi-analytical asymptotic theory

  28. The accuracy of the semi-analytical asymptotic theory

  29. The accuracy of the semi-analytical asymptotic theory

  30. Cloud top height determination from a satellite The geometry of the problem

  31. Cloud top height determination from a satellite The accuracy of the forward model Nadir observation, solar zenith angle – 20 degrees Cloud optical thickness –20.

  32. Cloud top height determination from a satellite The accuracy of the forward model

  33. Cloud top height determination from a satellite The physical principle behind the retrieval

  34. Cloud geometrical thickness determination from a satellite Preliminary results !

  35. Table 1. Characteristics of selected space instruments, related to measurements of the backscattered light in the oxygen A-band (7550-7750 ). Instrument Platform Year Spectral interval, Spectral resolution, Spatial resolution, km2 GOME ERS-2 1995 5760-7940 3.3 40*320 SCIAMACHY ENVISAT 2002 6040-8050 4.8 30*60 MERIS ENVISAT 2002 7600 25 0.3*0.3 or 1.1*1.1 GLI ADEOS-II 2002 7630 80 0.25*0.25 and 1.0*1.0 POLDER ADEOS-II 2002 7633 7651 100 400 6.0*7.0

  36. Cloud top height determination from SCIAMACHY Typical SCIAMACHY spectra in the oxygen A-band

  37. Cloud top height determination from SCIAMACHY

  38. Cloud top height determination from SCIAMACHY

  39. Cloud top height determination from GOME data using oxygen A-band information as compared to ATSR-2 IR retrievals (ERS-2 satellite)

More Related