Cubesat Reception of MODE-S Data from Civil Aircraft

The Met Office has deployed a network of five ground-based receivers in the UK which are intercepting routine  ADS-B and Mode-S EHS (Enhanced Surveillance) messages broadcast by civil aircraft in response to interrogations by air traffic control (ATC) radars. The information in the messages is used to derive high quality wind and lower quality temperature observations at ~4s intervals from most aircraft flying in UK airspace. The total cost of the hardware was only  ~€10k yet the network is currently delivering up to 6.2 million observations per day (including ~ 1000 profiles)  or  ~ 20 times the volume of upper-air wind observations obtained from all other sources combined. Locating the receivers on weather radar towers ensures a good horizon (hence coverage), and enables sharing of the high-bandwidth weather radar communications. Ongoing costs are equivalent to ~€0.01 per daily wind observation,  compared to ~€25 for AMDAR observations over the UK.   Experiments to assimilate these data into UK numerical forecast models are under way and displays of the data for  use by weather forecasters have been developed.

 Global availability of  Mode-S data is increasing as ATC radars are progressively  modernised and more are requesting the data from aircraft. This trend, along with the potential demonstrated so far with the UK receiver network, have prompted thoughts as to how data coverage could be extended to other regions in future. There seems to be three main possibilities - either deployment of local ground-based receivers, similar to the UK model;  establishing  a constellation of low-earth-orbit satellites (e.g. cubesats) that include an ADS-B and Mode-S receiver as part of the payload; or obtaining bulk data from ATC authorities around the world. The first two of these options are outlinedl here.