Effects of Solar Radiation Modification on Temperature Variability Over Ghana.

Abstract

Africa continues to face increasing climate variability, particularly in southern West Africa (SWA), where extreme events linked to aerosol loading and atmospheric circulation changes have intensified. In Ghana, the Harmattan season (December-February) is characterized by substantial intrusion of Saharan dust, which significantly alters surface energy balance and temperature conditions. This study investigates the spatial and temporal variability of dust concentration, solar irradiance, and temperature over Ghana using a multi-decadal dataset (1990–2020) derived from satellite remote sensing products (MODIS AOD, MERRA-2 radiation fields) and ground-based observations from twenty-two (22) Ghana Meteorological Agency synoptic stations. Statistical analyses, including correlation tests and Mann–Kendall trend assessments, were applied to quantify long-term patterns and interactions among the variables. The results show a marked temporal increase in dust concentration across northern and transitional zones, accompanied by reductions in both surface temperature and solar irradiance during peak Harmattan months. Seasonal decomposition highlights consistently elevated dust loading in December–February compared to the minor dry season (September–November), with contrasting patterns during the rainy seasons (March-May and June–August), when dust concentrations were lowest and irradiance highest. Spatial analyses further reveal that ecological gradients, land cover characteristics, and local atmospheric conditions influence the magnitude and distribution of dust radiation-temperature relationships. The study demonstrates that dust aerosols exert strong radiative cooling effects by attenuating incoming solar radiation and moderating surface temperatures, with significant spatial and seasonal variability across Ghana. These findings improve understanding of aerosol-climate interactions in SWA and provide essential insights for climate resilience planning, environmental management, solar energy optimization, and policy development in a warming climate.