Trend analysis of remotely sensed and forecasted precipitation in Iceland 1982-2050

Precipitation is a major energy resource in Iceland. This study employs the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) dataset to examine how precipitation patterns have evolved across Iceland from 1982 to 2021 and forecast them for the period 2022-2050.  The data confirms the known basic pattern of substantial precipitation in the south, while the northern interior plains are relatively arid.  The maximum precipitation is found in the South-East, but values are lower than suggested by glaciological and runoff data.  There is a non-significant overarching trend in annual precipitation across the country. However, a statistically significant declining trend (R>0.3, p-value=0.05) is observed in the interior regions of the East and Northeast regions. Conversely, a statistically significant increasing trend (R>0.3, p-value=0.05) is detected in coastal areas of these two regions. Future forecasting (2022-2050) suggests a very slight increase in Iceland's annual precipitation (approximately 0.6 mm/year). The findings of this study underline the importance of local scale monitoring of precipitation and comparison of methods of assessment of true ground precipitation.