Deutscher WetterdienstMeasurement Technology
Humidity Measurements by Aircraft of the E-AMDAR Fleet
TECO 2008
Axel HoffDeutscher WetterdienstObserving Networks and DataOffenbach am MainGermany
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
ACARSAircraft
Communications Addressing
and Reporting
System
AMDAR = Aircraft Meteorological Data Relay
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Sampling rate = 10 suntil 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
Desce
nt
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
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
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
AMDAR in Numbers (for 2007)
Activated Aircraft Reports per Day
DWD 289 21 000
E-AMDAR 600 35 000
AMDAR worldwide 2 800 250 000
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
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
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
SpectraSensors, WVSS-II Version 2006
• Infrared Absorption Spectrometer 2f method Tunable Diode Laser
• Output: Water Vapor Mass Mixing Ratio
Air SamplerFuselage
24 cm
SEB
Function
Sampling Tube
24 cm SEB
Sensor System
SEB (System Electronics Box)
Air Sampler
Hoses for connection Air Sampler with SEB
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Installation on the Aircraft
Air Sampler
4.8 m
4 o‘Clock Position
Exterior View
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Interior ViewSEB
FWD
Inlet Hose, Heated
Outlet Hose, Non-Heated
Frame
Skin
Air Sampler
Installation on the Aircraft
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Costs per Vertical Profile
(€)
AMDAR without humidity measurement 6
AMDAR, surcharge for humidity 30
Radiosonde + accessories (consumables only) > 200
Cost Estimate for AMDAR Humidity Profiles
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Results of the Flight Operation
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Temperature
Dewpoint
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
EU4593
EU5331
EU6564
Bias (Model - Observation) RMS
Verification against COSMO-EU
July 200812:00 UTC
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
RMSE
Verification against COSMO-EU
September 200812:00 UTC
EU4593
EU5331
EU6564
Bias (Model - Observation)
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Bias
RMSEMixing
Ratio (g/kg)
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Bias
RMSE
Mixing Ratio (g/kg)
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
Bias
RMSE
Mixing Ratio (g/kg)
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
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
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
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
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
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 linkfrom aircraft to ground
Observing Networks and Data – November 2008
Deutscher WetterdienstMeasurement Technology
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.
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