Rayleigh Scattering of the Solar Radiation in the Terrestrial Atmosphere and Its Assessment in the Polar Regions

The scatteringScattering of sunlight by molecules of the terrestrial atmosphere, known also as Rayleigh scatteringReyleigh scattering was a subject of detailed studies in the past century, and as a result, various theoretical algorithms allowing the calculation of the atmospheric Rayleigh optical depthReyleigh optical depth (ROD) have been developed and are currently used in both scientific studies and operative air monitoring. It was found that the ROD depends strongly on the surface pressure and the thermal conditions of the troposphere. Realistic ROD estimates are very important for the studies of the aerosol loadings in the air, especially in the polar atmospheres, where the attenuations of the solar radiation by aerosols and gas molecules turn out to be close to each other or even lower for aerosol as compared to the molecular scatteringMolecular scattering in the ultraviolet and deep blue regions of electromagnetic spectrum. To evaluate the ROD, standard atmospheric modelsAtmospheric models were widely used. Calculations based on the usage of radiosounding data collected at several polar stations were also recently performed. The present survey reviews the most used approaches for ROD assessment and summarises the results achieved for the polar regions. In addition, an attempt to improve the continuity of the ROD estimates over the ArcticArctic and AntarcticaAntarctica was made by using profiles of pressure, temperature and water vapour content provided by the ERA5 reanalysisERA5 reanalysis.