1. Deutscher Wetterdienst Measurement Technology Humidity Measurements by Aircraft of the E-AMDAR Fleet TECO 2008 Axel Hoff Deutscher Wetterdienst Observing Networks and Data Offenbach am Main Germany

2. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 ACARS Aircraft Communications Addressing and Reporting System AMDAR = Aircraft Meteorological Data Relay

3. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Sampling rate = 10 s until 150 s after start Sampling rate = 50 s 20 min after start Sampling rate = 7 min Descent beginning at 18000 ft Sampling rate = 40 s Touch down Reports: Aircraft Identification Date Time (UTC) Position Altitude (Pressure) Temperature Wind Speed Wind Direction Water Vapor Mass Mixing Ratio Ascent Enroute Descent

4. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 BUFR: DWD(LH) FM 42: SMHI(SAS) Meteo France(AF) UKMO(BA) KNMI(KLM) EUMETNET AMDAR (E-AMDAR) Sampling Points of 24 h over Europe

5. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 AMDAR in Numbers (for 2007)

6. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Humidity sensor enters the European AMDAR fleet 3 aircraft of the Airbus A320 family Typical daily flight program over Europe: distance:300 - 3000 km up to 6 ascents + descents

7. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 SpectraSensors, WVSS-II Version 2006 Infrared Absorption Spectrometer 2f method Tunable Diode Laser Output: Water Vapor Mass Mixing Ratio Air Sampler Fuselage 24 cm SEB Function Sampling Tube 24 cm SEB Sensor System SEB (System Electronics Box) Air Sampler Hoses for connection Air Sampler with SEB

8. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Installation on the Aircraft Air Sampler 4.8 m 4 o‘Clock Position Exterior View

9. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Interior View SEB FWD Inlet Hose, Heated Outlet Hose, Non-Heated Frame Skin Air Sampler Installation on the Aircraft

10. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Costs per Vertical Profile (€) AMDAR without humidity measurement6 AMDAR, surcharge for humidity30 Radiosonde + accessories (consumables only)> 200 Cost Estimate for AMDAR Humidity Profiles

11. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Results of the Flight Operation

12. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Temperature Dewpoint

13. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008

14. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008

15. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 EU4593 EU5331 EU6564 Bias (Model - Observation) RMS Verification against COSMO-EU July 2008 12:00 UTC

16. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 RMSE Verification against COSMO-EU September 2008 12:00 UTC EU4593 EU5331 EU6564 Bias (Model - Observation)

17. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Bias RMSE Mixing Ratio (g/kg)

18. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Bias RMSE Mixing Ratio (g/kg)

19. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Bias RMSE Mixing Ratio (g/kg)

20. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Trial‘s Result of the WVSS-II Version 2006: Constant routine operation within E-AMDAR Relative Accuracy within ± 10 % (during the first weeks) Drift (because of missing Laser Burn-In time) After a few months of operation: bias of partly 10 to 20 % Rel. Humidity Limit of detection ≈ 0.05 g/kg (80 ppmv)  lower 2/3 of the Troposphere High RMSE because of limited coding in the data link from aircraft to ground

21. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Consequences by the manufacturer SpectraSensors Inc. due to the resuls of NOAA / NWS and E-AMDAR / DWD: „Re-engineering“ → WVSS-II Version 2008 leading to -stability in the electronics -tightness of the Laser head resulting in -relative accuracy within ± 5 % -detection limit < 0.015 g/kg (24 ppmv) → complete Troposphere

22. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Planings for further steps Replacement of the old (2006) WVSS-II units on the Airbus A319 Separate test flights on research aircraft, such as possibly the Airbus A340 (MOZAIC) -intercomparison sensor on board -WVSS-II house-keeping data -cyclic interchange: aircraft ↔ laboratory Decision about more sensors Format improvement for data link from aircraft to ground

23. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 AMDAR, quo vadis Expansion and densification of the network on a global level: -inclusion of more airlines, -greater use of night-time starts and landings, -optimizing of the data supply. E-AMDAR / BoM Aircraft providing additional measurable variables -humidity (to catch up with radiosondes), NWS / NOAA E-AMDAR -geometric altitude (GPS, GLONASS, GALILEO,...), -air chemistry, aerosols, -turbulence, -icing. Correction methods for systematic error components. International standards for aircraft manufacturers: WMO / E-AMDAR -ex-works AMDAR configuration of the on-board software, -ex-works mechanical and electrical precautions for humidity sensor interfaces.

24. Deutscher Wetterdienst Measurement Technology Observing Networks and Data – November 2008 Questions or comments?