Relationship between airborne electrical and total water content measurements in ice clouds

• Published in: Atmospheric research 2020-06, Vol.237, p.104836, Article 104836
• Main Authors: Bouchard, Aurélie, Lalande, Philippe, Laroche, Pierre, Blanchet, Patrice, Buguet, Magalie, Chazottes, Arnaud, Walter Strapp, J.
• Format: Article
• Language: English
• Subjects: Engineering Sciences; Physics
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/j.atmosres.2019.104836

During the High Altitude Ice Crystal -High Ice Water Content (HAIC-HIWC) project, instrumented aircraft were flown in the vicinity and inside deep tropical convective clouds. Among the probes installed on one of these aircraft, were the Isokinetic Probe (IKP2), to retrieve the cloud total water content (TWC) and the AMPERA (Atmospheric Measurement of Potential and Electric field on Aircraft) system to provide information on the electrostatic state of the atmosphere and the aircraft. AMPERA is an electric field mill network which locally measures the electrostatic field at the aircraft fuselage. The distribution and amplitude of the electrostatic field on the aircraft skin depends on the atmospheric electrostatic field around the aircraft and the net electric charge of the aircraft. This latter parameter depends on the balance between the triboelectric current due to the impact of the cloud particles on the aircraft fuselage, the current due to the charged particles emitted by the engines, and the corona current emitted by the aircraft. Based on the flights of the HAIC-HIWC campaigns, which were conducted almost exclusively in cloud composed of ice particles, a comparison between the total water content recorded by microphysical sensor and the aircraft net charge has highlighted the possibility of deducing an estimate of the TWC from the aircraft electrical potential. In contrast to conventional TWC probes which sample a local area of the atmosphere, the AMPERA system uses the aircraft as a sensor and provides an overall estimation of its net TWC exposure. This study provides the first results of the efficacy of the electrostatic method through comparisons with direct in-situ bulk TWC measurements in ice clouds. •A new approach for the estimation of water content in ice clouds, tested during in flight campaign, is proposed.•The AMPERA system is an electric field mill network, measuring locally the electrostatic field at the aircraft fuselage.•The AMPERA system uses the aircraft as a sensor and provides an estimation of the total water content.•The relationship between airborne electrical and microphysical measurements has been highlighted.•This new approach could be useful for real-time detection as a first guess for total water content.