Preprints
https://doi.org/10.5194/egusphere-2024-2273
https://doi.org/10.5194/egusphere-2024-2273
14 Oct 2024
 | 14 Oct 2024

Retrieving Tropospheric Refractivity Structure using Interferometry of Aircraft Radio Transmissions

Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, and Edmund K. Stone

Abstract. Detailed measurements of atmospheric humidity in the lower atmosphere are currently difficult and expensive to obtain. For this reason, there is interest in the development of low-cost, high-volume opportunistic technologies to acquire measurements of tropospheric humidity. We demonstrate the use of interferometry to measure the atmospheric refraction of the Automatic Dependent Surveillance-Broadcast (ADS-B) radio transmission routinely broadcast by commercial aircraft. Atmospheric refraction is strongly influenced by changes in humidity, and refractivity observations have proved to be an effective source of humidity information for numerical weather prediction models. A prototype ADS-B interferometer has been developed that can simultaneously perform angle-of-arrival (AoA) interferometry and decode ADS-B signals. Combining the measured AoA of the ADS-B signal with the known position of the aircraft (information contained within the ADS-B signal) allows the bending of the signal due to refraction to be determined. Combining the measured bending of numerous ADS-B signals allows for information concerning the refractivity structure to be extracted. An adjoint model was derived and used to retrieve synthetic one-dimensional refractivity profiles in a variety of atmospheric conditions. The results from an experiment using a prototype ADS-B interferometer are shown and initial refractivity profiles are retrieved. Sources of uncertainty in the observations and the retrieved refractivity profiles were explored and future work was suggested.

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Journal article(s) based on this preprint

11 Sep 2025
Retrieving tropospheric refractivity structure using interferometry of aircraft radio transmissions
Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, and Edmund K. Stone
Atmos. Meas. Tech., 18, 4433–4451, https://doi.org/10.5194/amt-18-4433-2025,https://doi.org/10.5194/amt-18-4433-2025, 2025
Short summary
Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, and Edmund K. Stone

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2273', Anonymous Referee #2, 21 Nov 2024
    • AC1: 'Reply on RC1', Ollie Lewis, 26 Mar 2025
  • RC2: 'Comment on egusphere-2024-2273', Anonymous Referee #3, 07 Mar 2025
    • AC2: 'Reply on RC2', Ollie Lewis, 26 Mar 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2273', Anonymous Referee #2, 21 Nov 2024
    • AC1: 'Reply on RC1', Ollie Lewis, 26 Mar 2025
  • RC2: 'Comment on egusphere-2024-2273', Anonymous Referee #3, 07 Mar 2025
    • AC2: 'Reply on RC2', Ollie Lewis, 26 Mar 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Ollie Lewis on behalf of the Authors (27 Mar 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (31 Mar 2025) by Laura Bianco
RR by Anonymous Referee #3 (09 Apr 2025)
ED: Reconsider after major revisions (16 May 2025) by Laura Bianco
AR by Ollie Lewis on behalf of the Authors (31 May 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (06 Jun 2025) by Laura Bianco
RR by Anonymous Referee #3 (20 Jun 2025)
ED: Publish as is (25 Jun 2025) by Laura Bianco
AR by Ollie Lewis on behalf of the Authors (26 Jun 2025)  Manuscript 

Journal article(s) based on this preprint

11 Sep 2025
Retrieving tropospheric refractivity structure using interferometry of aircraft radio transmissions
Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, and Edmund K. Stone
Atmos. Meas. Tech., 18, 4433–4451, https://doi.org/10.5194/amt-18-4433-2025,https://doi.org/10.5194/amt-18-4433-2025, 2025
Short summary
Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, and Edmund K. Stone

Data sets

ADS-B Interferometry - (22/09/2023) Ollie Lewis and Chris Brunt https://doi.org/10.5281/zenodo.12783749

Model code and software

ADS_B_refractivity Ollie Lewis https://github.com/osl202/ADS_B_refractivity

Ollie Lewis, Chris Brunt, Malcolm Kitchen, Neill E. Bowler, and Edmund K. Stone

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Short summary
Humidity observations are crucial for an accurate weather forecast. We propose a new way to measure humidity by measuring how radio signals from commercial aircraft are refracted by the atmosphere. Humidity affects the refractive index of air, allowing its presence to be detected. With thousands of flights in the airspace over the United Kingdom every day, there is the potential for a large increase in the number of humidity measurements for use in weather forecasting models.
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