Evaluation of global solar radiation and cloud cover variability in northern Antarctic Peninsula

The Antarctic Peninsula (AP) region is well known for high variability of atmospheric parameters compared to the central part of Antarctica. This area is influenced by high cyclonic activity which results in high cloud cover and strong surface wind. Due to complex orography and the effect of AP mountains, different amount of cloud cover occurs along western and eastern coast. As the cloud cover is one of the most important atmospheric factors affecting the Earth's energy budget, its changes cause significant spatiotemporal variability of incoming solar radiation. Solar radiation is a key driver of many physical and biological processes in Antarctic ecosystems, as well as the main component of surface net radiation. Together with other radiative fluxes and atmospheric transmittance is frequently used in many atmospheric and glaciological simulations. To study annual and seasonal differences in global solar radiation (GR), measurements of shortwave downward fluxes were carried out at J.G. Mendel station (JGM) located on the north-eastern side of the peninsula and King Sejong station (KSJ) on the western side of AP. The GR monitoring was undertaken with class A pyranometers in the period 2011–2016. Furthermore, theoretical intensity of GR was calculated using radiative transfer model and used for estimation of cloud modification factor at both stations. Factors influencing the GR variability were retrieved from ERA5 reanalysis, consisting of the following parameters: surface pressure, surface albedo, water vapor, cloud cover and total ozone column (Ozone Monitoring Instrument). The results showed significantly higher intensity of GR (up to ~30.5 %) and higher values of cloud modification factor (~28.5 %) at JGM station compared to KSJ station. The main factor influencing daily variation in GR was solar zenith angle at both stations (~50 % of variability). The influence of cloud cover, main atmospheric factor, was more pronounced at JGM station (~22 %) compared to KSJ station (~15 %), while water vapor was less important compared to cloud cover (~7 % at JGM and ~17 % at KSJ station respectively).