A new method of retrieving atmospheric refractivity structure

It is proposed to obtain information on atmospheric refractivity structure by measuring the angle of arrival (AoA) radio signals routinely broadcast commercial aircraft. The would be measured at hill-top sites using a simple two-element interferometer. Knowledge aircraft’s location (information conveniently contained within broadcasts) and AoA will enable bending calculated. As measurable only occur grazing incidence, sources either very close horizon, or similar height interferometer, are essential. routine navigational data broadcasts from civil aircraft represent ideal source. In areas high air traffic density such as UK, \~105-106bending measurements may possible each day. Numerical weather prediction models assimilate angles retrieved GNSS occultation data, so it anticipated that assimilation methods could developed able make good use this new source data. Sensitivity tests were performed estimate resolution humidity retrievals assuming target accuracy 0.01°. Simulated annealing was used demonstrate ability retrieve relative mixing ratio vertical profiles measurements. shown for observed with an 0.01° should \~5% \~0.5 g/kg respectively. An achievable hardware costing \~€10k, however further development still required.