Deutscher Wetterdienst Measurement Technology Humidity Measurements by Aircraft of the E-AMDAR Fleet TECO 2008 Axel Hoff Deutscher Wetterdienst Observing

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


ACARSAircraft

Communications Addressing

and Reporting

System

AMDAR = Aircraft Meteorological Data Relay



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



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



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



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



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



Installation on the Aircraft

Air Sampler

4.8 m

4 o‘Clock Position

Exterior View



Interior ViewSEB

FWD

Inlet Hose, Heated

Outlet Hose, Non-Heated

Frame

Skin

Air Sampler

Installation on the Aircraft



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



Results of the Flight Operation



Temperature

Dewpoint







EU4593

EU5331

EU6564

Bias (Model - Observation) RMS

Verification against COSMO-EU

July 200812:00 UTC



RMSE

Verification against COSMO-EU

September 200812:00 UTC

EU4593

EU5331

EU6564

Bias (Model - Observation)



Bias

RMSEMixing

Ratio (g/kg)



Bias

RMSE

Mixing Ratio (g/kg)



Bias

RMSE

Mixing Ratio (g/kg)



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



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



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



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.



Questions or comments?

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Deutscher Wetterdienst Measurement Technology Humidity Measurements by Aircraft of the E-AMDAR Fleet TECO 2008 Axel Hoff Deutscher Wetterdienst Observing