Changes in potential evaporation over the last four decades in Hornsund SW Spitsbergen

Svalbard is one of the fastest warming regions of the earth, over the last 40 years SW Spitsbergen has experienced large changes in hydrological and meteorological conditions. Evaporation is an important component of the hydrological cycle but remains understudied in High Arctic Svalbard. Cold climate evaporation in Spitsbergen is often neglected and commonly used evaporation estimates date to the early 2000’s. In this study, potential evaporation (PET) estimates for the period 1982 to 2023 were calculated using ten different PET models and meteorological data from the Polish Polar Station Hornsund (SW Spitsbergen). The ten potential evaporation methods includes radiation-based (Abtew), temperature-based (Hamon), radiation-temperature based (Hargreaves Samani) and combined models (Penman Montheit) and more. Trends in annual and interannual potential evaporation have been analyzed and compared to changes in meteorological conditions. The study evaluates the influence of the choice of PET model and the derived changes in potential evaporation estimates. The results of the study show a large spread in the amount of annual PET estimates ranging from ~30mm/y (Kharrufa) through ~300mm/y (Penman-Monteith) up to ~450mm/y (Abtew). Trends analysis shows different outcomes depending on the length of the averaging period. Using a daily timescale, PET models tend to show more similar patterns of changes than using monthly timescales. That corresponds well with changes in the meteorological conditions.