A study of tropospheric radio refractivity and its relationship to climate over Egypt from 1979 to 2019: patterns and mechanisms

It is well established that non-standard atmospheric conditions are responsible for the anomalous propagation and refractivity characteristics in the troposphere, which in turn affect radio communication processes. The current study aims to estimate and map the tropospheric radio refractivity and its variations across Egypt, focusing on its relationship with certain climatic and meteorological elements. The study also seeks to identify the principal components of these climatic factors and their spatial patterns that significantly influence radio refractivity, and to compare these at different pressure levels in the troposphere over Egypt. The analysis is based on the ERA5 monthly averaged gridded dataset, which has a spatial resolution of 0.25° × 0.25°, covering the period from 1979 to 2019. The findings of the study indicated that atmospheric radio refractivity decreases gradually with increasing height over Egypt. Furthermore, a strong positive correlation was found between radio refractivity and humidity across all seasons and pressure levels. In contrast, a negative correlation was observed between refractivity and temperature throughout all seasons and pressure levels across Egypt and its geographical regions. Additionally, the study reveals significant impacts of climate change on radio refractivity trends during the period from 1979 to 2019 over Egypt.