Introduction to Global Aircraft Based Observations

ABO WorkshopECMWF, Reading12th/13th February 2020

Steve Stringer,

E-ABO Programme Manager

Introduction to Global Aircraft Based Observations

Global ABO – We’ve come a long way!

Aircraft observations have been around for a long time…and were being routinely made before there were radiosondes

ADS-BADS-C

AMDARMode-S EHS/MRAR

Global ABO

…plus AIREPs, PIREPs, TAMDAR, AFIRS …plus UAVs & Research aircraft

Global ABO – Temperature & WindAMDAR

ADS-C

12 Programmes

40+ Airlines

Global ABO – AMDAR Temperature & Wind

• Australia • Canada• China• E-AMDAR• Hong Kong, China• Japan

• LATAM• Mexico• New Zealand• Korea• South Africa• USA

Aer Lingus Delta Air Lines NAV Canada

Air Canada Jazz Dragon Airlines Northwest Airlines

Aerolíneas Argentinas EasyJet Airline Novair Scandinavia

Aeromexico Eurowings Qantas Airways

Air France Federal Express Scandinavian Airlines

Air New Zealand Finnair Shandong Airlines

Air Nippon Airways Japan Airlines SkyTraders

Alaska Airlines JetConnect (Qantas) South African Airways

American Airlines Korean Air Southwest Airlines

Asiana Airlines LATAM Airlines Sunclass Airlines

Austrian Airways Lufthansa Cargo United Airlines

British Airways Lufthansa CityLine United Parcel Service

Cathay Pacific Lufthansa Germanwings

China Southern Airlines Lufthansa Passage

Global ABO – Temperature & Wind

Global ABO – Water Vapour

WVSS & TAMDAR WVSS & TAMDAR (exc. MDCRS)

WVSS TAMDAR

Global ABO – Turbulence & Icing

TAMDAR produces:• Temperature• Wind• Humidity• Turbulence • Icing

Global ABO: What is actually measured & reported by aircraft?

What is measured: Pressure

Pressure (and speed) is measured by standard aircraft sensors known as Pitot-static tubes

• Static pressure is used to calculate pressure altitude (PALT)

• Static pressure (normal air pressure) and dynamic pressure (caused by flight) can be used together to calculate the aircraft’s speed as a Mach number (M)

What is measured: Pressure (Altitude)

• Temperature is measured by a Total Air Temperature (TAT) probe

• Sensor faces into the airflow and brings air to a stop inside the sensor where its temperature is measured

What is measured: Temperature

This halting effect causes the air to warm. This warmer value is known as the Total Air Temperature (TAT)

This is then converted into Static Air Temperature (SAT) by onboard software, which is equivalent to the true external air temperature

What is measured: Temperature

What is measured: Temperature – linking to Mach number

Static Air Temperature (SAT) is a function of sensor probe and Mach Number (aircraft speed relative to the speed of sound).

Mach Number is derived from total and static pressures

What is measured: Wind Speed and Direction - Method

The measurement of the three-dimensional wind vector from an aircraft is a complicated problem!

Using the aircraft navigation system and the airspeed system (Pitot-static tubes) together with the TAT sensors, it is possible to estimate – to a high enough degree of accuracy:

• The velocity of the aircraft with respect to the ground below it

(Vg = ground speed)

• The velocity of the aircraft with respect to the air around it

(Va = airspeed).

V

Va

Wind Vector (V) is then given by: V = Vg – Va.

What is measured: Sensor Interdependencies

Observation reporting: On-board systems

Applies for AMDAR/ AIREP/ ADS-C• Not all Avionics systems

are the same!• Different manufacturers

& different versions• Downlink Formats are

standardised (ARP & AMDAR)

• Other parameters included with AMDAR message, e.g roll angle, to show aircraft is manoeuvering

Observation reporting: Downlinking

Monitoring & Metadata

Mode-S

E-ABO Regional requirements

EUCOS area: 70°W to 40°E; 10°N to 90°N

Observations: Spatial resolution: 250kmTemporal resolution: 3 hours

Quality: Maximum temperature RMSE ≤ 1.5 K

(≤ 1.0 K goal) Maximum wind RMSVD ≤ 5 m/s. (≤ 3.5m/s goal)• for E-ABO, these are monitored wrt

ECMWF Global model

In addition, some NMHSs (DWD, KNMI, MeteoFrance, MetO) have additional National requirements, which require additional national funding

Observations: Spatial resolution: <100km/ Every national airportTemporal resolution: 1 hourTimeliness: T+15 mins or less

Q

Questions?