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Monitoring Atmospheric Humidity from Commercial Aircraft by MOZAIC-IAGOS:

Monitoring Atmospheric Humidity from Commercial Aircraft by MOZAIC-IAGOS: In-sights from the Past and Present into the Future Herman G. J. Smit ( h.smit@fz-juelich.de ) Forschungszentrum Juelich (ICG-2). Past and Present: MOZAIC. Humidity Sampling. Quality Assurance & Synergy of Data.

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Monitoring Atmospheric Humidity from Commercial Aircraft by MOZAIC-IAGOS:

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  1. Monitoring Atmospheric Humidity from Commercial Aircraft by MOZAIC-IAGOS: In-sights from the Past and Present into the Future Herman G. J. Smit (h.smit@fz-juelich.de) Forschungszentrum Juelich (ICG-2) Past and Present: MOZAIC Humidity Sampling Quality Assurance & Synergy of Data Future: IAGOS H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  2. Why Monitoring Humidity in Upper Troposphere ?? Doubling CO2-concentration: 2-5oC Temperature increase 1/3-part: direct via CO2 2/3-part: via positive feedback of water vapor+clouds Upper troposphere most sensitive region in climate change H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  3. Routine Aircraft Measurements in the Global Observing System: The Link Between Surface and Space H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  4. MOZAIC: Humidity Sampling H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  5. MOZAIC: Humidity Sensor in Rosemount Air Inlet System SAT RHS TAT, RHD • In inlet speed reduction (Mach0.8 to 0) with adiabatic conversion: ► Heating (SAT to TAT) : in UT  30oC • ► Compression (PS to PD): in UT  Factor 1.6 • RH at detector (RHD) << RH sampled air (RHS) • ►At cruise altitude RHS 13 x RHD Rosemount Housing Total Temperature Model 102 BX H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  6. In: Helten et al., J.Geophys.Res., 1998 MOZAIC-Humidity Device: Pre-&Post Flight Calibration • Regular calibration (every 500 flight hours) • In environmental simulation chamber • Against Lyman()-fluorescence hygrometer • Under realistic flight conditions of humidity, temperature and pressure • Evaluation of two year record of pre- and post-flight calibrations • Results agree well with in-flight intercomparisons [Helten et al. Geophys.Res.1998, 1999] H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  7. MOZAIC Relative Humidity in Upper Troposphere (UT) over Atlantic % • MOZAIC provided the first • climatology of humidity in the UT • Large variability in time and • space • More than 30% of UTH-data • are Ice Super Saturated (ISS) • But less than 0.5-1% of data • are Saturated to Liquid • Long Term Changes ?? • Control of Humidity in UT?? H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  8. MOZAIC Critical aspects on inlet system • Separation solid / gas phase • Particle enhancement • Evaporation droplets & crystals • Wall memory effects • Well defined P & T (cq. SH & RH)-conditions Ice Super Saturation over North Atlantic: • More than 35% of UTH ice super saturated • But less than 1% of observations are saturated to liquid H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  9. Performance MOZAIC Humidity Device in Clouds Evaporation of Ice Crystals ??????? • Clouds are clearly detected as „RHI-burst“ to 200% by the Lyman ()-Total H2O • In clouds the MOZAIC-Humidity Device not exceeding 100% RHI H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  10. MOZAIC: Ice Super Saturation (ISS) in the UT Horizontal extent of ISS regions • 30% of the UT shows ice super saturation (ISS) • Global models do not reproduce ISS • ISS relates with sub-visible cirrus • Small scale phenomenon(X < 200 km, Z < 1-2 km) • Difficult to see by satellites • Importance: contrail & cirrus formation; • radiative balance; OH formation H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  11. AIRS MOZAIC 100 120 80 20 40 60 0 RH (liq.%) -100 50 -50 0 100 AIRS - MOZAIC RH (liq.%) MOZAIC- UTH: Comparison with AIRS-Satellite over 2003 (Work by Co PI: Andrew Gettelman, NCAR, Boulder, USA) • Development of proper „matching“ citeria of coincidence in space and time: • A priori estimation of contribution of natural variability • Direct comparison at (x,y,z,t) • Indirect by optimizing statistics of coincidence by using backward trajectories H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  12. Spec. Hum. Temp. Rel. Hum. Involvment Temperature Measurements Using TAT-Housings: Comparison Temperature Aircraft versus MOZAIC In addition, important aspect at low temperatures: Which H2O-saturation pressure Es(T)-table has been applied ??? H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  13. Development of Automatic In-flight Calibration (IFC) • Based on the technology and experience obtained • during 8 years of MOZAIC-operation. • Long-term zero drift of MOZAIC-device, particularly • at low temperatures, is the critical and accuracy • determining parameter • On-line determination of long term zero drift during • dry stratospheric episodes (5ppmv water vapor) as a • function of temperature. • On-Line correction of zero drift of RH-measurements H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  14. MOZAIC In-Flight Calibration (IFC): Validation In-flight comparison during SPURT with Ly()-Hygrometer (FISH) Comparison with MOZAIC IFC RH(IFC) – RH (MOZAIC) [%RH] H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  15. AMDAR Designed for automatic on-line sampling of humidity from aircraft for weather forecasting Diode laser (2f-detection) Compact ( 2.5 kg) Can new airborne WVSS-II measure humidity in UT and LS?: State of the Art • US-NWS has installed on 25 UPS aircraft since 2005 , now in evaluation phase but with plans to extend to large number • Poor documentation on evaluation of performance • FZJ has evaluated in the laboratory in 2005 • DWD has installed on three A320 of Lufthansa since 2007 • In the loop: plans to install on a MOZAIC/IAGOS A340 of Lufthansa ? Goal NWS: Reduce radiosounding network and replace by AMDAR H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  16. Compact Sensors for Measuring Humidity on In-Service Aircraft H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  17. AMDAR = Aircraft Meteorological DAta Relay Aboard Commercial Aircraft For Weather Forecasting Reports: • Aircraft Identification • Date • Time (UTC) • Position • Altitude (Pressure) • Temperature • Windspeed • Wind Direction • Planned: Water Vapor Mass Mixing Ratio H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  18. Can new airborne WVSS-II measure humidity in UT and LS???: Performance tests at Environmental Simulation Facility at Jülich, Germany AMDAR Designed for automatic on-line sampling of humidity from aircraft for weather forecasting Diode laser (2f-detection) Compact ( 2.5 kg) • WVSS at Frostpoint Temperatures: • Above ~290 K: No reliable signal • 225 K – 290 K: Good performance: • Accuracy ±(5-10)% • 215 K – 225 K: Rapid declining sensitivity, • Limited accuracy: <±(10-15)% • Below ~ 215 K: Below detection limit (80 ppmv) • Poor performance in UT/LS H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  19. MOZAIC/IAGOS: Summary QA-H2O/T Performance • Pre-and Post flight calibration every 500 flight hours) [Helten et al. 1998] • In-flight comparisons (In-service & Research) [Helten et al., 1999] • Evaluation in SPARC-water vapor assessment 2000 report • Development in-flight calibration (IFC) method [Smit et al., 2008] • Evaluation of detection of ice superation saturation [in-preparation] • Assessment of performance of 12 years of MOZAIC-flight operation [in preparation] • 12 year Climatology of MOZAIC-H2O/T data available in MOZAIC-data base at Toulouse • Participating in COST-action WaVaCS (Watewr Vapor in the Climate System) • Participating in new, second SPARC water vapor assessment • New instruments are under investigations. H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  20. H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  21. Extra Material H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  22. ECMWF Model Now With Ice Super-Saturation Tompkins, Gierens, Rädel, Quart.J.Roy.Met.Soc, 2007 H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  23. MOZAIC: Comparison Temperature Aircraft versus MOZAIC] • Both measured with Rosemount TAT • Assumption full adiabatic conversion: • Measurement of TAT (σ=±0.25K) • Determination M from TAP (σ=±0.25hPa) • & SAP (σ=±0.35hPa) • Determination SAT (σ=±0.50K) • Practice: • TAT-recovery only 99.5-99.7% • Correction tables based on wind duct • measurements (made in 1960/1970‘s) • Dependece on angle of attack • Dependence on location at aircraft skin • Remaining sources of uncertainties =0.2 TAT = Total Air Temperature SAT = Static Air Temperature TAP = Total Air Pressure SAT = Static Air Pressure H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  24. Outstanding Issues UTH-ISS Observations • Rosemount-TAT inlet systems: • No indication of evaporation of ice crystals • Evaporation of liquid droplets • Large temperature sensitivity of H2O-saturation: • Review of water vapor saturation tables at low temperatures • Temperature measurement needs more attention: • Adiabatic recovery factor • Location at aircraft • Comparison with other in-situ temperature sensing technics • Scale analysis of spatial and temporal distribution of ISS • Climate impact of ISS H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  25. In: Helten et al., J.Geophys.Res., 1998 MOZAIC Humidity Device: Performance and Quality Assurance RHCAL (Ti) =a (Ti)+b (Ti) x RHUNCAL (Ti) • Calibration procedure: • Pre-flight calibration: a1(Ti) & b1(Ti) • - Installation in A340 • - 500 h of flight operation • - Exchange of MHD • 2. Post-flight calibration: a2(Ti) & b2(Ti) • - Cleaning RH- & T-sensor • Pre-flight calibration • - Etc. etc. • Uncertainty of RH is derived from: • Difference between pre-and post • flight calibration of RH • Uncertainty Temperature • Evaluation of two year record of pre- and post-flight calibrations • Results agree well with in-flight inter comparisons[Helten et al., J.Geophys.Res.1999] H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  26. MOZAIC-Humidity: In-Flight Comparison with Frost Point Hygrometer (Ovarlaz) on Falcon (DLR/Nov.1997) [Helten et al., J.Geophys.Res.1999] H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  27. 400 Slope = 0.98 (r=0.70) Offset= 3.6 ppmv 300 200 MOZAIC-UTH (ppmv) 100 0 100 300 400 200 POEM-UTH (ppmv) Coincidence criterion: 2.5º x 2.5º x 1 km x 6 h Total: 200 Coincidences April 1998-Feb.2000 MOZAIC-UTH: Comparison with POEM III Satellite • POEM III= Polar Ozone and Aerosol Measurement III satellite operational since April 1998 • Good agreement POEM with MOZAIC (Slope=0.98) • Large variations due to • Atmospheric variability & • Limited resolution of POEM (X=250 km) Source: Nedoluha et al., POAM III measurements of water vapor in the upper troposphere and lower most stratosphere, J. Geophys. Res., 2002 H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  28. MOZAIC-UTH: Comparison with MLS/UARS Satellite • MLS observe no ice super saturation (retrieval and/or limited horizontal resolution) • MLS lower than MOZAIC (Slope=0.64) • Large variations due to • Atmospheric variability & • Limited resolution of POEM (Z=4-5 km) Source: Read et al., UARS Microwave Limb Sounder upper tropospheric humidity measurement: Method and validation, J. Geophys. Res., 2001 Coincidence criterion: 1º x 1º x 1 km x 3 h Total: 384 Coincidences Aug.1994-Dec.1997 H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  29. MOZAIC: Distribution Relative Humidity in UT over Atlantic Z = 9-12 km, PV  2.0pvu, 10oW-70oW, Aug 1994 - June 2000 38% ISS 22% ISS 15% ISS 15% ISS H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  30. Performance MOZAIC Humidity Device & ISS: Artifacts due to Evaporation of Ice Crystals ??????? H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  31. MOZAIC-IFC: In-Flight Correction of Zero Drift of RH-measurements H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  32. Operational Aspects of MOZAIC-Humidity Device From Board Commercial Aircraft Every 6 months cleaning sensor at airport: rins with destilled water (1 min) rins with alcohol ( 1min) heat out (1 min @ ~90oC) Every 2 year overal check at service company: exchange humidity device and send to service company overall check of device (new sensors, calibration etc.). Outlook: automatic cleaning procedure at airport collaborations with companies for instrumental and QA support (e.g.Vaisala) H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  33. IAGOS-ERI: Time Table • 4/2008 IAGOS Design Study completed, - Prototypes available, - Partner airlines committed • 2008 First aircraft equipped and commissioned: O3, CO, H2O, Cloud Droplet Probe, NOy • 2009 Certification for CO2 and aerosol • 2016 20 aircraft equipped and commissioned • 2028 20 years of data available ~ 150 000 flights http://www.fz-juelich.de/icg/icg-ii/iagos Coordinator: Dr. Andreas Volz-Thomas E-mail: A.Volz-Thomas@fz-juelich.de H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

  34. WVSS-II Candidates for Automatic Monitoring Humidity by Commercial Aircraft H2O from MOZAIC-IAGOS // Herman Smit/FZJ ISSI-H2O Bern 11-14 Feb.2008

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