Instrumentation and fair weather criteria for atmospheric electric field measurements in west African dust environments

Abstract

West Africa's notorious Harmattan dust storms have long defeated atmospheric electric field monitoring efforts, creating a massive blind spot in global atmospheric electricity research despite the region's critical role as Earth's largest dust source and lightning hotspot. We present a successful methodology for continuous atmospheric electric field measurements in extreme dust environments, deploying a specially adapted Campbell Scientific CS110 electric field mill at Lokoja, Nigeria (7°49'N, 6°44'E) with revolutionary environmental protection, automated cleaning systems, and tropical optimised grounding networks. Traditional fair-weather criteria catastrophically failed, excluding 78% of scientifically valuable data during Harmattan periods when PM₁₀ concentrations exceeded 1000 μg m⁻³ and electric fields reached 5000 V m⁻¹. Our breakthrough region-specific criteria using 4000 m visibility thresholds combined with stability filters achieved a remarkable 94.3% data completeness over 30 months while retaining 46% of measurement days, representing 275% improvement over standard approaches. The validated framework achieved measurement uncertainties of ±3.4% for hourly means, demonstrating that reliable atmospheric electricity monitoring is feasible even under the challenging aerosol conditions. These advances further open unprecedented opportunities for dust storm early warning systems, regional climate modelling, and fundamental understanding of global atmospheric electrical circuits.