| Summary: | Stable water isotopes (δ18O and δD) in precipitation can help to understand hydrological and atmospheric processes within the water cycle. While long-term monthly precipitation isotope datasets are available, limited data exists on daily precipitation samples. In this study isotopic values of daily precipitation from 30 June 2016 to 17 February 2020 sampled in Reykjavík are reported and interpreted in relation to weather data from the Icelandic Meteorological Office (IMO). A large range in δ18O (-17.48 to -0.67‰), δD (-132.3 to +1.3‰) and the d-excess (d = δD - 8δ18O) (-7.5 to +31.4‰) values was observed in the daily precipitation data. Significant anti-correlation was observed between d-excess and temperature (r = -0.61 ± 0.05) and specific humidity (r = -0.56 ± 0.05). Weaker correlation was found between isotopic values (δ18O) and the above meteorological parameters (r = 0.26 ± 0.05 and 0.22 ± 0.05). Some differences were also observed when correlations were studied by seasons. Results from sampling a low-pressure front passing Reykjavík (12 samples) show large isotopic inter variability that can be correlated with temperature and specific humidity. Moderate correlation is found between the observed isotopic data and the isotope-enabled ECHAM5-wiso climate model. The model’s parametrization of precipitation could be improved by taking into consideration higher resolution isotope data. Relationship between the isotopic precipitation data and the North Atlantic Oscillation (NAO) suggests anti-correlation between δ18O (and δD) and the NAO index, especially during winter months, though statistically non-significant. Database with results from water isotope measurements performed at the Institute of Earth Sciences since 2006 was constructed, to facilitate available water isotopic data for future research. Stöðugar samsætur súrefnis (δ18O) og vetnis (δD) í úrkomu geta hjálpað til við að skilja ýmis ferli vatnshringrásarinnar. Alþjóðlegur gagnagrunnur um samsætur úr mánaðar úrkomusýnum er tiltækur, en niðurstöður ...
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