Seasonal Patterns of Atmospheric Dust Loading and Solar Radiation Reduction in Katsina State

Atmospheric dust loading during the harmattan season exerts a measurable attenuating effect on surface solar radiation in Nigeria's North West zone, with implications for both agricultural and renewable energy systems. This study characterizes seasonal patterns of atmospheric dust concentration and associated solar radiation reduction in Katsina State, using MODIS Aerosol Optical Depth (AOD) retrievals and pyranometer sunshine duration records from NiMet's Katsina Airport station for 2019 to 2023. A physical-empirical model linking AOD values to fractional solar radiation reduction was developed and calibrated against direct radiation measurements. Results demonstrate that peak harmattan dust loading in December and January is associated with a mean solar radiation reduction of 28 percent compared to clear-sky estimates, with extreme dust events causing reductions exceeding 45 percent on individual days. Analysis of sunshine duration records confirms a corresponding reduction in bright sunshine hours of 1.8 to 2.5 hours per day during peak harmattan periods. The energy yield implications for grid-tied photovoltaic systems in Katsina State are quantified, showing potential capacity factor reductions of 18 to 23 percent during the December-January peak dust period. The study recommends that solar energy developers in Katsina incorporate harmattan dust attenuation corrections in solar resource assessments and consider anti-soiling coatings for panel surfaces. Keywords: dust loading, aerosol optical depth, solar radiation, Katsina, photovoltaic.