Snow gauge undercatch and its effect on the hydrogen and oxygen stable isotopic composition of precipitation

ABSTRACT

We investigated the influence of post-collection changes and snow gauge undercatch on the stable isotopic compositions of winter precipitation. Post-collection changes by evaporation or sublimation can be severe, and may be minimized, but not eliminated, by emptying collection gauges immediately after snowfall. Snow gauge undercatch caused two main effects: a small direct effect caused by preferential separation of snow particles during snowfall, and a much larger effect on the measured stable isotopic compositions of average annual precipitation as a result of under representation of winter precipitation. Despite these effects, however, we found little change to calculated local meteoric water lines (LMWL) for Saskatoon, SK, Canada. A comprehensive 27-year LMWL for Saskatoon which incorporates these effects can be described by δ²H = 7.69 ± 0.096 × δ¹⁸O – 2.22 ± 1.72 (r² = 0.97, n = 208).

KEYWORDS:

• Groundwater
• hydrogen-2
• isotope hydrology
• local meteoric water line
• oxygen-18
• precipitation
• snow
• snow gauge undercatch

Acknowledgements

We thank Randy Schmidt for field collections and Chantel Gryba, who assisted with stable isotope measurements. J. McDonnell and Garth van der Kamp provided critical and helpful reviews of an earlier version of this manuscript. Two anonymous referees provided additional helpful comments.

Disclosure statement

No potential conflict of interest was reported by the author.

ORCID

Geoff Koehler http://orcid.org/0000-0003-3864-3346

Additional information

Funding

This study was funded by Environment and Climate Change Canada.