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ISSI Working Group on Atmospheric Water Vapor, 11 Feb 2008

ISSI Working Group on Atmospheric Water Vapor, 11 Feb 2008. Water vapor observations using the CFH. Holger Vömel Cooperative Institute for Research in Environmental Sciences University of Colorado. Overview.

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ISSI Working Group on Atmospheric Water Vapor, 11 Feb 2008

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  1. ISSI Working Group on Atmospheric Water Vapor, 11 Feb 2008 Water vapor observations using the CFH Holger Vömel Cooperative Institute for Research in Environmental Sciences University of Colorado

  2. Overview • Science issues: Trend (stratosphere / upper troposphere) Supersaturation Use in forecasting and models • Measurement issues: Absolute accuracy In-cloud measurements Frostpoint above 0C • Logistical issues: World wide coverage Instrument availability Cost Radiosonde manufacturer interaction

  3. Cryogen Frost layer Thermistor Heater μ Controller Detector Air flow IR LED Lens Mirror Cryogenic Frostpoint Hygrometer (CFH) • Microprocessor control • Vertical Range: surface to ~28 km (surface to ~25 km on ascent) • Uncertainty: troposphere: > 4% MR stratosphere: ~ 9 % • Phase sensitive detector: electronic sunlight filter • No liquid/ice ambiguity • Weight: ~ 400 gr • Currently interfaced with ECC ozone sonde and Vaisala RS80 • >300 soundings

  4. Science issue: Trends

  5. Boulder trend From Scherer et al., ACPD 2007

  6. Boulder trend From Scherer et al., ACPD 2007

  7. Where to measure trend? Methane oxidationand PSCs Processes controllingentry of water into stratosphere From Holton et al., Rev. Geophys. 1995

  8. Science issue: Supersaturation

  9. Supersaturation from WB-57 From Gao et al., Science, 2003

  10. Harvard Lyman alpha - CFH

  11. RH ice from tropical CFH soundings

  12. Supersaturation in cloud

  13. Measurement issue: Absolute accuracy

  14. 1 10 100 1 Pressure (hPa) 10 100 Pressure (hPa) 2 4 6 8 10 12 14 Mixing Ratio (ppmv) 2 4 6 8 10 12 14 Mixing Ratio (ppmv) Frostpoint vs balloon remote sensing Aura MLS / FIRS-2 / MkIV / NOAA FP Sep 2004 Sep 2005Ft Sumner (~35ºN) Balloon comparisons

  15. CFH vs ACE-FTS

  16. CFH vs MLS

  17. CFH vs FISH

  18. CFH vs WB-57 instruments JPL TDL

  19. CFH vs. FLASH TC4 Costa Rica August 2007

  20. CFH vs. FLASH AMMA/Ticosonde Veranillo: Niger vs Costa Rica August 2006

  21. CFH vs WB-57 instruments Harvard Lyman alpha

  22. CFH must be considered an absolute reference instrument

  23. Measurement issue: In (liquid) clouds

  24. Measurement in clouds

  25. Wet bias with liquid phase?

  26. Comparison with groundbased GPS PWV

  27. Comparison with groundbased GPS PWV

  28. Condensate phase Liquid : Coarse frost: Fine frost:

  29. Logistical issues: World wide coverage

  30. CFH Observation sites (campaign based)

  31. Instrument availability Instrument needs (low estimate): 6 sites (2 tropical, 2 mid latitude, 2 polar) 2x per month 144 soundings per year  Industrial manufacturing

  32. Instrument availability BUT conflict of Business interests • Profit • Trade secrets Science interests • Economical observations • Understanding of instrument • Open access policy

  33. Discussion points • CFH observations provide highest level of confidence • Improve confidence in observations by cross checks of observations (ground and balloon based, satellites, aircraft) • Science issues to be addressed need large number of soundings • Need to address industrial production issue, involvement of radiosonde manufacturers

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