Surface radioactivity influences on atmospheric electricity during stable boundary layer conditions

Nicoll, K. A. ORCID: https://orcid.org/0000-0001-5580-6325, O’Neill, O., Miller, C., Paatero, J. and Ulich, T. (2027) Surface radioactivity influences on atmospheric electricity during stable boundary layer conditions. Atmospheric Research, 343. 109237. ISSN 0169-8059 doi: 10.1016/j.atmosres.2026.109237

Abstract/Summary

Ionisation from radon natural radioactivity and galactic cosmic rays generates charge in the lower atmosphere. This enables atmospheric electrical processes including thunderstorm electrification and the Global atmospheric Electric Circuit (GEC). Variations in Rn-222, influenced by soil moisture and meteorological conditions, perturb local conductivity and atmospheric electric field (Potential Gradient, PG), yet quantitative relationships between ionisation rate and PG remain poorly documented. This study presents long-term measurements (2018-2023) of PG and ionisation (Rn-222 (at 6m) and gamma (at 1.5m)) analysed alongside meteorological data for the first time at Sodankylä, Finland. Rn-222 concentration in air typically maximises overnight into early morning before sunrise. During fair weather, Rn-222 ionisation rate ranged from 0.06-12.14 cm-3s-1 (median 0.81 cm-3s-1) with median total ionisation rate 5.73 cm-3s-1. PG analysis demonstrates a general dominance of global signals from the GEC on average in fair weather conditions across all seasons in PG variability. However, overnight stable boundary layer conditions produce clear PG variability linked with ionisation rate during low-level temperature inversions. For total ionisation rate variations from 2.9 to 15 cm-3s-1, PG ranged from 155 V/m to 24 V/m. The magnitude of these observed PG changes is shown to be comparable with ion balance theory. Radiosonde temperature profiles demonstrated a strong link between boundary layer stability, and the overnight PG minima/ionisation rate maxima, supported by statistical analysis from 45 daily case studies. Because stable conditions are typically classified as fair weather, these findings highlight the importance of accounting for ionisation variability in early morning PG measurements when interpreting GEC observations.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/131171
Identification Number/DOI	10.1016/j.atmosres.2026.109237
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Elsevier
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