Isotopic composition of winter precipitation in Altai foothills

Abstract

In recent years, some general circulation models have been improved by using stable water isotopologues, such as HDO (δD) and H218O (δ18O). In this paper, the results of a study of the isotopic composition of precipitation sampled in the winter seasons of 2014-2015 and 2015-2016 in Altai foothills are presented. The isotopic composition varied greatly: from -17.4 ‰ to -30.63 ‰ for δ18O and from -132.1 ‰ to -235.0 ‰ for δD in 2014-2015; from -15.9 %„ to -26.8 ‰ for δ18D and from -118.5 ‰ to -207.7 ‰ for δD in 2015-2016. The weighted average values of δ18O and δD for both seasons were close to each other (-21.2 ‰ and -160.1 ‰ for the first season and -20.4 ‰ and -157.5 ‰ for the second season), while the values of dexc differed significantly. A trajectory analysis (by the Hybrid Single Particle Lagrangian Integrated Trajectory - (HYSPLIT) model) has shown that the difference in the isotopic composition of the precipitation is largely associated with the change of the main source regions of atmospheric moisture, namely, the change of the North Atlantic waters (the 2014-2015 winter season) for the inland waters (the 2015-2016 winter season). A comparison of the results of an isotopic analysis has shown good agreement with data of the Global Network of Isotopes in Precipitation (GNIP) interpolated for 1960-2010. Thus, with a proper interpretation the data of the isotopic composition of the winter precipitation in Altai foothills can be used for this territory as an alternative source of the GNIP network data.