Microclimatological variability of incoming solar irradiance and snow cover availability near native vascular plants in the maritime Antarctic

Incoming solar irradiance is a crucial factor for the survival of native vascular plants in Antarctica, providing the primary energy source for local terrestrial vegetation growth. We analyse the microscale variability of incoming solar irradiance at the surface and evaluate its applicability as a proxy parameter for detecting snow cover availability in remote regions. The study is based on a network of 38 temperature and light sensors deployed within an established monitoring site in the Argentine Islands Kyiv Peninsula region during 2017–2025. At the microscale level, in sites where Colobanthus quitensis and Deschampsia antarctica occur, typical austral-summer irradiance values range from 200 to 500 W ⋅ m–2, with deviations of up to ±60% driven by local microscale conditions. We analysed the periods with near-zero measured irradiance, indicating stable snow cover that typically occurred from April to October. Being measured at the surface, solar irradiance disappearance can serve as a proxy for snow cover formation. The snow formation timing was relatively consistent, whereas the snowmelt timing varied significantly across sites. At the locations of native vascular plants distribution, the snow-free period varied in the range of 90 to 200 days, being dependent on microclimatological features. No statistically robust differences in the intra-annual irradiance cycle were detected between sites occupied by C. quitensis and D. antarctica; however, irradiance duration suggests a tendency for C. quitensis to preferentially occupy locations with longer irradiated periods. This study emphasises the importance of accounting for incoming solar radiation at the microscale and demonstrates the potential of light sensors as a proxy for assessing snow cover availability in remote Antarctic regions where direct observations are not possible.