Isotope Records from Mongolian and Alpine Ice Cores as Climate Indicators

Abstract

The link between long term changes in the isotopic composition of precipitation and surface air temperature at a given location is of exceptional importance for paleoclimatic studies, as ahs been demonstrated by many recent publications based on the isotope records from polar ice cores. By means of direct comparison with instrumental data, this paper evaluates the potential of the deuterium and oxygen-18 records from two continental glaciers for monitoring climatic trends. The isotopic data presented characterize climatically contrasted enviroments. The records from the Swiss glacier show distinct seasonal variations. Oxygen-18 is fairly well correlated with the instrumental record of atmospheric temperature; the seasonal differences in deuterium excess reflect nearness to the oceanic moisture source. By contrast, the isotope data from the Mongolian site show poor correlation with atmospheric temperature. The seasonal variations in deuterium excess, with higher values during summer time, indicate that precipitation largely originates from re-evaporated continental moisture sources. In both cases however, the correlation with temperature is significantly improved by the elimination of values derived from years where major changes in seasonal distribution and/or snow loss obviously have occurred, thereby distoring the isotopic ratios for that particular year. Depending on the site selected for study, the stable isotope composition of ice cores should therefore be viewed not only as a proxy for atmospheric temperature, but also as an additional hydrometeorological parameter and source indicator for atmospheric moisture.

Seasonal and inter‐annual variability of the moisture sources for Alpine precipitation during 1995–2002

“…If robust signals of moisture source changes are present in the stable isotope time series in precipitation, this information could potentially be used to reconstruct a time series of moisture source variability in the Alpine region, e.g. using ice cores from Alpine glaciers (Schotterer et al, 1997;Schwikowski et al, 2005).…”

“…Information on moisture sources and transport conditions is often inferred indirectly from the interpretation of stable isotopes in precipitation and paleo archives, such as Alpine glaciers (Schotterer et al, 1997). However, Rozanski et al (1982) concluded that in order to understand the stable isotope signature in local precipitation in Central Europe, the whole transport history, and therefore the influence of circulation patterns must be considered.…”

Snow Stable Isotope Composition Variability Related to the Upper Mendoza River Basin Hypsometry

“…7). O in the Alps, in the order of -0.17 / -0.2 ‰ every 100 m (Mariani et al, 2014;Windhorst et al, 2013;Poage and Chamberlain, 2001;Schotterer et al, 1997;Siegenthaler and Oeschger, 1980), the slope of the altitudinal effect is variable (from 0.1 ‰ to 0.6 ‰ / 100 m), depending on the temperature and isotopic fractionation during condensation, altitude, orographic characteristics, moisture source (Horvatinčić et al, 2005), and the trajectories of the air masses (Aouad-Rizk et al, 2005). In the Cordillera Principal geological province, the stable isotope values of streams and rivers showed a slight altitudinal effect in a previous study, attributed to seasonality and changes in the relative contribution from different water sources to streams .…”

“…The consequence is a gradient of decreasing natural abundance of heavy isotopes with increasing altitude, observed in many mountain areas of the world (Mariani et al, 2014;Windhorst et al, 2013;Poage and Chamberlain, 2001;Schotterer et al, 1997;Niewodniczanki et al, 1981;Siegenthaler and Oeschger, 1980). Generally, the δ 18 O impoverishment, varies between -0.15 to -0.5 ‰ per 100 m increase in altitude, with a corresponding -1 to -4 ‰ δ 2 H value decrease (Clark and Fritz, 1997).…”

Atmospheric circulation change in the central Himalayas indicated by a high-resolution ice core deuterium excess record

“…However, only a few studies have so far addressed d from ice cores in nonpolar regions (Schotterer et al 1997, Kreutz et al 2003, Ramirez et al 2003, Aizen et al 2005, Vimeux et al 2008. Notably, a decadal resolution d profile obtained from the Dasuopu ice core from the Himalayas (Thompson et al 2000) is the single long term (AD 1000 to 2000) record for this re gion.…”