Small Airborne Electric Field Sensor for Atmospheric Science applications

Abstract

Earth’s atmosphere is electrified, and an important electrical parameter is the global atmospheric electric field (E-field). Measuring this E-field aloft provides insights into the ionospheric potential (linked to global lightning), the distribution/magnitude of charge in clouds (which can influence cloud droplet interactions), and insights into long-range dust transport (which can be affected by electrification). Traditional airborne platforms, such as manned aircraft or weather balloons, have limitations regarding cost, accessibility, or controllability. This thesis explores the possibility of using small Unmanned Air Vehicles (sUAV) as an alternative for E-field measurements aloft. The small nature of these platforms requires developing a compact lightweight E-field sensor (EFS). The project focuses on four main components: i) the compact EFS; ii) a customised sUAV; iii) data processing methods; and iv) specific operational procedures.

A novel linear sliding screen EFS design was developed, which avoids the vibrations caused by traditional rotating electric field mills. The final prototype EFS weighs less than 500g, has a resolution of 5V/m, and was tested both in lab and field settings. The chosen UAV platform weighs in total 4.3kg, it is based off a Skywalker X8 frame, uses (mostly) COTS modules, is catapult launched, and it has an emergency parachute. COMSOL simulations inform the decision on sensor placement and help visualize the E-field distortion pattern due to the platform itself. Data processing techniques involve time series analysis, digital signal processing, and interpreting aircraft telemetry. From an operations point of view, this project defines procedures and mission roles while prioritizing safety.

Flight trials showed that the airborne EFS prototype responds to aircraft changes in attitude (such as roll angle changes), and it was used to generate a vertical E-field profile up to 90 meters. A low-flying experiment examined the electrostatic effects of passing through smoke plumes. At the intersection of science, engineering, and operations, this work demonstrates that, with due care and attention to platform and sensor design/placement, small UAVs are viable tools for observing the atmospheric E-field aloft, and it encourages further adoption by atmospheric researchers.

Date of Award	25 Jun 2025
Original language	English
Awarding Institution	University of Bath
Supervisor	Manuchehr Soleimani (Supervisor), Keri Nicoll (Supervisor), Peter Wilson (Supervisor), Pejman Iravani (Supervisor) & Uriel Martinez Hernandez (Supervisor)