Spatial and temporal variability of stable water isotopes in snow related hydrological processes (original) (raw)
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Spatial distribution of stable water isotopes in alpine snow cover
2013
Abstract The aim of this study was to analyze and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analyzed. Snow in four Swiss catchments was sampled at the end of the accumulation 5 period in April 2010 and a second time in Mai 2010 and analyzed for stable isotope composition of 2 H and 18 O.
A new method of snowmelt sampling for water stable isotopes
We modified a passive capillary sampler (PCS) to collect snowmelt water for isotopic analysis. Past applications of PCSs have been to sample soil water, but the novel aspect of this study was the placement of the PCSs at the ground-snowpack interface to collect snowmelt. We deployed arrays of PCSs at 11 sites in ten partner countries on five continents representing a range of climate and snow cover worldwide. The PCS reliably collected snowmelt at all sites and caused negligible evaporative fractionation effects in the samples. PCS is low-cost, easy to install, and collects a representative integrated snowmelt sample throughout the melt season or at the melt event scale. Unlike snow cores, the PCS collects the water that would actually infiltrate the soil; thus, its isotopic composition is appropriate to use for tracing snowmelt water through the hydrologic cycle. The purpose of this Briefing is to show the potential advantages of PCSs and recommend guidelines for constructing and installing them based on our preliminary results from two snowmelt seasons.
2018
Stable water isotopes have become a key element in hydrological and atmospheric research topics. Hydrologists aim to close the water cycle, and the improvement of measurement techniques and models makes that they come closer every time. Especially the atmospheric part of the cycle is not yet fully understood, and this study aims to get an increased understanding about the isotopic signals in the snow pack, and if the snow pack record may be used to derive an improved understanding of the importance of atmospheric river events for the Norwegian snow cover. The Finse area has been chosen as a proxy site for Norway, and 215 samples have been taken to analyze for stable water isotopes. 11 different snow profiles that were computed from snow pits that were excavated during the fieldwork were compared with the isotope values for δ18O and d-excess, and with meteorological data provided by the meteorological institute of Norway. The snow pack from the same winter season (2016-2017) was simu...
2001
Understanding the spatio-temporal variations of isotopic tracers in complex mountainous environments can assist with seasonal and inter-annual hydrological process studies. In addition, if components of a hydrological balance can be isotopically characterised through time at a basin end-point, then they can potentially be used to evaluate the hydrological balance predicted in a model run. Over one hundred samples were collected of bulk snowpack, glacial ice, rainfall and various forms of groundwater/baseflow from the Bow Valley in the Canadian Rockies in an attempt to characterise the spatio-temporal variations of stable oxygen isotope compositions for each of these end members. A discussion of the observed changes in each of the flow component signatures with regard to the hydrological processes that may be controlling these dynamic changes in signature is provided. The paper ends with a generalisation (or conceptual model) of the oxygen isotope signatures for each of the major hyd...
Arctic Snow Isotope Hydrology: A Comparative Snow-Water Vapor Study
Atmosphere
The Arctic’s winter water cycle is rapidly changing, with implications for snow moisture sources and transport processes. Stable isotope values (δ18O, δ2H, d-excess) of the Arctic snowpack have potential to provide proxy records of these processes, yet it is unclear how well the isotope values of individual snowfall events are preserved within snow profiles. Here, we present water isotope data from multiple taiga and tundra snow profiles sampled in Arctic Alaska and Finland, respectively, during winter 2018–2019. We compare the snowpack isotope stratigraphy with meteoric water isotopes (vapor and precipitation) during snowfall days, and combine our measurements with satellite observations and reanalysis data. Our analyses indicate that synoptic-scale atmospheric circulation and regional sea ice coverage are key drivers of the source, amount, and isotopic composition of Arctic snowpacks. We find that the western Arctic tundra snowpack profiles in Alaska preserved the isotope values f...
Journal of Geophysical Research: Atmospheres
Stable water isotopes are used as a paleothermometer in ice cores for climate reconstructions over the past millennia. The underlying physical processes involved in the isotope‐temperature relation, however, unfold at much shorter timescales. Here, we study the temporary archival of frontal passages in the seasonal Alpine snow cover. We combine five snow profiles sampled in winter 2017 at the Weissfluhjoch with a quantitative snow layer age reconstruction and atmospheric reanalysis data to characterize the circulation and clouds associated with the precipitation producing synoptic‐scale cold and warm fronts. We find that the vertical cloud structure and the air parcels' net cooling during transport leave a distinct imprint in the δ18O and δD vertical profile in the snow. The near‐surface humidity gradient at the moisture source is reflected in the second order isotope parameter deuterium excess. In the cold season, these environmental conditions during cloud formation and at the...
Isotope studies of inner snow layers in a temperate region
Hydrological Processes, 2002
Post-depositional change of isotope concentration was investigated in a temperate snow pack. Daily snow pit studies were carried out at Moshiri, Hokkaido, for about a week in April 1998. During this time the snow layers were at the melting point. Isotope analysis was conducted on snow particles and the liquid water in between the particles every 5 cm in depth, and on the precipitation and the runoff water (from the bottom of the snow pack) collected during the observation period. It was found that the oxygen isotope concentration in the liquid part was smaller by about 2‰ than the solid part of the wet snow. The difference between the isotope concentrations of the liquid and the solid was low in the surface snow layer, but increased at the bottom. The results suggested that isotope fractionation took place between the liquid and the solid, when liquid water (formed by melting at the snow surface layer) flowed groundwards.
Annals of Glaciology, 2008
To assess the seasonal stability of the d d 18 O stratigraphy in winter snowpacks in the Canadian Rocky Mountains, snow pits were sampled over three accumulation seasons at two field sites. These sites, Opabin and Haig Glaciers, are $160 km apart at similar elevations and represent windward and lee-slope environments respectively. At both sites, snow pits were sampled at one glacier and one forefield location throughout each accumulation season. Intra-seasonal changes in d 18 O at each site were examined to determine the extent of post-depositional modification of isotope stratigraphies. At both glacier sites, there was minimal temporal change before the onset of spring melt in all years. In addition, the similar structure of d 18 O profiles from both glacier sites suggests that regional controls govern the isotopic composition of solid-phase precipitation across the study area. At forefield locations, the absence of an insulating layer of ice at the base of the snowpack allowed for vapour transport and post-depositional modification of the seasonal d 18 O signal. This did not result in consistent changes to the mean d 18 O, deuterium excess and dD-d 18 O regression line slopes in the lower layers of snow, and the observed smoothing of d 18 O profiles was less than that simulated by applying a diffusion model to these snowpacks. Annals of Glaciology 49 2008 96