The NISBO data set – high altitude daily precipitation stable isotope data since 2016

Since August of 2016, daily precipitation samples for stable isotope analysis are collected at the Sonnblick Observatory (SBO). The SBO is located on the peak of Mt. Hoher Sonnblick, at an elevation of 3106 m above sea level, on the main ridge of the Alps in Austrias Hohe Tauern Region [1, 2]. These samples are analyzed using laser absorption spectroscopy (OA-ICOS, LGR T-LWIA-45-EP) at ISOLAB Salzburg, geoconsults in-house laboratory, producing data for the precipitations δ²H, δ¹⁸O and δ¹⁷O stable isotope composition.

To our knowledge, this data set, both in location (highly alpine) as well as in temporal resolution (daily data) and length of the data (multiple, full years) is unique. The aim of this Poster is to raise awareness about this data set and to discuss preliminary findings, before publishing the data for further work.

As expected, the data show pronounced seasonal variations (up to approx. 25 ‰ for δ¹⁸O, 10 ‰ for δ¹⁷O and 120 ‰ for δ²H) and notable differences between the various years in the data set, which compares well to the longterm observation from the nearby Böckstein Station of the Austrian Network of Isotopes in Precipitation and Surface Waters (ANIP) [3, 4]. However, the ANIP station, located in a valley, at 1014 m a s l, is collected in monthly intervals only.

Besides these seasonal and annual variations, significant differences in isotopy between single precipitation events can be observed. At a maximum, from December 27. to December 28. 2017 (21,6 mm of precipitation) δ¹⁸O and δ²H drop from ‑8.07 and ‑85.89 ‰ VSMOW to ‑30.14 and ‑224.60 ‰ VSMOW, a difference of -22.07 and -138.71 ‰ respectively, within a day. Similarly, from March 04. to March 05. 2020 (2.5 mm of precipitation), δ¹⁸O and δ²H rise from ‑22.10 and -172.04 ‰ VSMOW to ‑2.22 and ‑47.05 ‰ VSMOW, a difference of +19.88 and +124.99 ‰.

Such changes, reflecting a multitude of possible causes, such as for example altitude effect or different sources of the precipitating moisture (Mediterranean vs. Atlantic in case of the Sonnblick) are generally not seen in the prevailing monthly data and pose an interesting field for further research.

In general, most of the data follow both, the global mean water line (GMWL [5]) and the Austrian mean water line (AMWL [6]); but a trend towards higher δ¹⁸O and δ²H values, resulting in a local, daily, water line of approx. δ²H = 6.3 δ¹⁸O – 18.1 for this high-alpine environment can be distinguished.

[1] https://www.sonnblick.net/en/about-us/

[2] https://www.sonnblick.net/en/the-observatory/location/

[3] KRALIK, PAPESCH, & STICHLER (2003): Austrian Network of Isotopes in Precipitation (ANIP): Quality assurance and climatological phenomenon in one of the oldest and densest networks in the world. Isotope hydrology and integrated water resources management: 146-149.

[4] https://www.umweltbundesamt.at/wasser/informationen/isotope/isotopenmessnetz-anip

[5] CRAIG, H. (1961): Isotopic Variations in Meteoric Waters. Science, 133: 1072-1073

[6] HAGER, B. & FOELSCHE, U. (2015): Stable isotope composition of precipitation in Austria. AJES, 108: 2-13