EMADDC: high-volume, high-quality, and timely wind and temperature observations from aircraft surveillance data (Mode-S EHS)

Wind and temperature observations from aircraft are of major importance for aviation meteorology and numerical weather prediction (NWP). The European Meteorological Aircraft Derived Data Centre (EMADDC) system processes aircraft surveillance data received from air traffic control (ATC) and other partners and converts them into upper-air observations of wind and temperature. Only so-called Mode-S Enhanced Surveillance (Mode-S EHS) data can be used because these data contain the air vector and ground vector of the aircraft from which a wind vector can be inferred. Temperature is derived from true airspeed and Mach number measurements. To produce high-quality observations, the data are processed in three steps: pre-processing, processing, and post-processing. The pre-processing is needed to obtain high-quality information and to calculate several correction values for correcting temperature observations and heading values. Processing converts the aircraft data into meteorological information, and finally post-processing guarantees that only high-quality information is made available.

The EMADDC system processes around 75×106 surveillance observations per day and produces over 55×106 observations of quality-controlled wind observations and 32×106 temperature observations in the European airspace per day. The average age of the observation is around 5 to 10 min, depending on the method of data delivery (files via ftp or streaming constantly).

The quality of the observations produced is verified by comparing these observation to other upper-air wind and temperature observations from radiosondes and Aircraft Meteorological Data Relay (AMDAR) and comparing them with NWP data. The quality of wind observations is almost identical to AMDAR, and the quality of the temperature of EMADDC observations is lower but with a bias of around zero, while AMDAR exhibits a positive bias of 0.5 K.

This paper presents the EMADDC (R2.2) system, operational since 2019.