Status of the cloud information service

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Status of the cloud information service

• Ping Wang, Piet Stammes, Maarten Sneep, Ronald
  van der A

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FRESCO atmospheric model
Rsim simulated reflectance Ac cloud top
albedo As surface albedo c
effective cloud fraction T
two-way transmission
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FRESCO atmospheric model
Rc Rs are single Rayleigh scattering
reflectances of cloudy and clear part of pixel
Tc, Ts are two way transmissions including O2
absorption and single Rayleigh scattering.
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Cloud model

• Effective cloud parameters
• Middle of the cloud is retrieved
• Useful for trace gas retrievals

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From FRESCO to FRESCO

• Effect on cloud information
• cloud pressure is higher ( 60-70 hpa)
• effective cloud fraction is a little larger
  0.02
• chi-square is smaller
• Effect on ozone
• Effect of FRESCO on O3 VCD is small
• TOSOMI 0.40 uses FRESCO (sc-v4), 0.42 uses
  FRESCO(sc-v5)
• Effect on tropospheric NO2
• NO2 becomes smaller
• Difference is usually small with a few exceptions
  (with large differences)

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Status

• Reprocessing of O3, NO2 using FRESCO
• Documentation up-to-date, including FRESCO
• Version control
• Web-access

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Time series cloud pressure
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Pixel sizes
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GOME-2 cloud product

• Status cloud information GOME-2
• FRESCO included in operational level 1 data
  delivery by EUMETSAT
• Optional delivery via TEMIS
• FRESCO product for GOME-2 data

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GOME-2 vs. SCIA cloud fraction/pressure
difference distributions
fraction
pressure
Mean difference-23 hPa, sigma108 hPa
Mean difference0.01, sigma0.12
Note SZA is larger for GOME-2 and time
difference in observation
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OMI cloud algorithm

• O2-O2 cloud product (OMCLDO2)
• From validation with MODIS
• Eff. cloud fraction abs. error 0.01 (standard
  dev. 0.10)
• From validation with PARASOL and CloudSat
• Cloud pressure abs. error 50 hPa (standard
  dev. 70 hPa)
• (source Stammes et al., 2007 Sneep et al.,
  2007)
• Daily global coverage, nadir pixel size is 13x24
  km2
• Comparable to FRESCO

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Possible extensions cloud product

• GOME-2 FRESCO products
• OMI cloud products
• Level 3 products for climate studies (new user
  group)