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S5P tropospheric ozone product:

S5P tropospheric ozone product: Convective Cloud Differential method First German S5P Verification Meeting Bremen, 28 - 29 November 2013 Pieter Valks DLR, Remote Sensing Technology Institute (IMF). Outline. Convective-Cloud-Differential (CCD) algorithm for S5P

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S5P tropospheric ozone product:

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  1. S5P tropospheric ozone product: Convective Cloud Differential methodFirst German S5P Verification Meeting Bremen, 28 - 29 November 2013 Pieter Valks DLR, Remote Sensing Technology Institute (IMF)

  2. Outline • Convective-Cloud-Differential (CCD) algorithm for S5P • Analyses of CCD method with GOME-2 data • Analyses of cloud parameters • Variability in stratospheric and upper tropospheric ozone • Tropical tropospheric ozone column • Further analyses and development for S5P

  3. S5P tropical tropospheric ozone with CCD method Convective-cloud-differential (CCD) method • above cloud and clear-sky ozone column measurements • Tropical tropospheric ozone columns (TTOC) below ~200 hPa S5P data required: • Total ozone columns • Effective cloud fractions, cloud albedo and cloud-top pressures (OCRA and ROCINN)

  4. S5P cloud parameters used for CCD method Effective cloud fraction • S5P_CLOUD_OCRA • f > 0.8 (stratospheric column) • f < 0.1 (cloud free) Cloud pressure and albedo • S5P_CLOUD_ROCINN • CTP < 300 hPa • CTA > 0.8 (deep convective clouds)

  5. Stratospheric ozone column calculation Above-cloud ozone column (ACOC) using S5P Level-2 total ozone product • Selection of S5P measurements in the tropics (20°N-20°S): • Deep convective tropical clouds (f > 0.8, CTP < 300 hPa, CTA > 0.8) • Low ozone concentrations inside cloud • East Indian Ocean / Western Pacific (70°E – 170°W) • Vac = SCD / AMFcloud (no ghost column) Stratospheric ozone column (monthly mean) • 1.25° latitude bands • Stratospheric ozone column independent of longitude

  6. Tropical tropospheric ozone column Tropical Tropospheric Ozone Column (TTOC) S5P Level-3 product • Selection of cloud-free S5P L2 ozone measurements (f < 0.1) • Vclear = SCD / AMFclear • Monthly (weekly) mean values on a 1.25° by 2.5° lat-lon grid (20°N-20°S) GOME-2 Tropospheric O3 Oct. 2010

  7. Analyses of CCD method with GOME-2 data • Analyses of cloud parameters • Variability in stratospheric and upper tropospheric ozone • Tropical tropospheric ozone column • Exemplary results • Comparison with ozonesonde measurements

  8. Cloud parameters (OCRA/ROCINN) Frequency of deep convective clouds (f > 0.8, CTP < 300 hPa, CTA > 0.8)

  9. Cloud parameters (OCRA/ROCINN) Frequency of deep convective clouds (f > 0.8, CTP < 300 hPa, CTA > 0.8)

  10. Cloud parameters (OCRA/ROCINN) Histogram of cloud pressure and albedo for Eastern Indian Ocean / Western Pacific (12.5°S - 12.5°N, 70°E – 170°W , f > 0.8) Cloud Pressure Jan. 2008 Cloud Albedo Jan. 2008

  11. Cloud parameters (OCRA/ROCINN) Histogram of cloud pressure and albedo for Eastern Indian Ocean / Western Pacific (12.5°S - 12.5°N, 70°E – 170°W , f > 0.8) Cloud Pressure July 2008 Cloud Albedo July 2008

  12. Variability in stratospheric ozone column Monthly mean stratospheric ozone column • 1.25° latitude bands between 20°S - 20°N • Assumption: stratospheric ozone column independent of longitude in tropics Comparison of GOME-2 CCD stratospheric ozone column with ozonesondes • Comparison for 8 SHADOZ sites • Bias: ≤ 3 DU • RMS differences: 3-7 DU Comparisons with other stratospheric ozone satellite measurements (Ziemke et al.) • TOMS CCD comparison with SAGE II (Bias: 1-4 DU; RMS differences: 4-5 DU) • OMI CCD comparison with MLS (Bias: 1-3 DU; RMS differences: 2-3 DU)

  13. Variability in upper tropospheric ozone Ozone concentrations in deep convective clouds (cloud slicing technique) Above-cloud O3 column Western Pacific 1-3 Oct. 2007 10-20ºS/160-180ºE Above-cloud O3 column Indian Ocean 1-3 Oct. 2007 10-20ºN/70-90ºE Mean ozone mixing ratio: 4 ~ppbv Mean ozone mixing ratio: ~7 ppbv

  14. Variability in upper tropospheric ozone Ozone concentrations in deep convective clouds (cloud slicing technique) Above-cloud O3 column Western Pacific 1-3 March 2008 0-10ºS/120-140ºE Above-cloud O3 column Indian Ocean 1-3 March 2008 0-10ºN/70-90ºE Mean ozone mixing ratio: ~8 ppbv Mean ozone mixing ratio: ~6 ppbv

  15. Tropospheric NO2 GOME-2B tropical tropospheric NO2 and ozone October, 2013 Tropospheric Ozone

  16. Tropospheric NO2 GOME-2 tropical tropospheric NO2 and ozone September, 2010 Tropospheric Ozone

  17. Comparison with ozonesonde measurements Natal, Brazil (5ºS, 35ºW) R: 0.89 Bias: -0.9 DU RMS: 3.4 DU

  18. Comparison with ozonesonde measurements Ascension Island (8ºS, 15ºW) R: 0.85 Bias: -1.4 DU RMS: 3.9 DU

  19. Comparison with ozonesonde measurements American Samoa (14ºS, 171ºW) R: 0.75 Bias: -1.7 DU RMS: 3.6 DU

  20. GOME-2 tropospheric ozone ENSO index Correlation between Nino 3.4 Temp. ENSO and Ozone ENSO index Nino 3.4 ENSO temp. index temperature anomalie in eastern Pacific Ozone ENSO index ozone column difference between western and eastern Pacific R = 0.90

  21. Further analyses and development for S5P Cloud parameters • Same cloud algorithms (OCRA/ROCINN) used for GOME-2 and S5P • Cloud selection criteria (f, CTP, CTA) to be optimized for S5P • dependent on FOV, ground pixel size, etc. • CCD method sensitive to albedo related instrument effects (e.g. TTOC bias between GOME-2A and GOME-2B) Spatial and temporal resolution • Temporal resolution: monthly, weekly, daily? • Valid latitude range varies with month (but only for tropics) • Spatial resolution: currently 1.25° x 2.5° lat-lon (GOME-2) • Analyse with OMI data and (simulated) S5P data Operational processing and product format • Realistic estimates of CPU / RAM / Product size • Product format • Implementation in PDGS (Level-3 product)

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