Radio Refractivity and Gradient Variations Across West Africa Climatic Zones: Implications for Microwave Systems
Keywords:
Radio refractivity, refractivity gradient, tropospheric ducting, super-refraction, climatic zones, West Africa, microwave communicationsAbstract
This study investigates the spatial and temporal variations of radio refractivity and refractivity gradient across different climatic zones in West Africa using 22 years of reanalysis meteorological data (temperature, pressure, and relative humidity). Ten representative locations from coastal, rainforest, savannah, and desert regions were analyzed to characterize radio wave propagation mechanisms across the sub-region. Surface refractivity exhibited distinct patterns, with values ranging from 372 to 419 N-units, showing clear seasonal and climatic zone dependencies. The refractivity gradient analysis revealed that tropospheric ducting is the predominant propagation condition across most locations, except for Monrovia where sub-refraction exceeds ducting at 1000 hPa and 975 hPa pressure levels. Atmospheric ducting was particularly pronounced in savanna and desert regions due to dry air conditions and temperature inversions. Super-refractive conditions prevailed at 975 hPa and 950 hPa in all climatic zones, especially during the dry season. This comprehensive characterization of radio refractivity parameters provides essential information for optimizing microwave communication systems design and performance across West Africa's diverse climatic regions.
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