Variations of oxygen-18 in West Siberian precipitation during the last 50 years

Abstract

Abstract. Global warming is associated with large increases in surface air temperature in Siberia. Here, we apply the isotope-enabled atmospheric general circulation model ECHAM5-wiso to explore the potential of water isotope measurements at a recently opened monitoring station in Kourovka (57.04 • N, 59.55 • E) in order to successfully trace climate change in western Siberia. Our model is constrained to atmospheric reanalysis fields for the period 1957-2013 to facilitate the comparison with observations of δD in total column water vapour from the GOSAT satellite, and with precipitation δ 18 O measurements from 15 Russian stations of the Global Network of Isotopes in Precipitation. The model captures the observed Russian climate within reasonable error margins, and displays the observed isotopic gradients associated with increasing continentality and decreasing meridional temperatures. The model also reproduces the observed seasonal cycle of δ 18 O, which parallels the seasonal cycle of temperature and ranges from −25 ‰ in winter to −5 ‰ in summer. Investigating West Siberian climate and precipitation δ 18 O variability during the last 50 years, we find long-term increasing trends in temperature and δ 18 O, while precipitation trends are uncertain. During the last 50 years, winter temperatures have increased by 1.7 • C. The simulated long-term increase of precipitation δ 18 O is at the detection limit (< 1 ‰ per 50 years) but significant. West Siberian climate is characterized by strong interannual variability, which in winter is strongly related to the North Atlantic Oscillation. In winter, regional temperature is the predominant factor controlling δ 18 O variations on interannual to decadal timescales with a slope of about 0.5 ‰ • C −1 . In summer, the interannual variability of δ 18 O can be attributed to shortterm, regional-scale processes such as evaporation and convective precipitation. This finding suggests that precipitation δ 18 O has the potential to reveal hydrometeorological regime shifts in western Siberia which are otherwise difficult to identify. Focusing on Kourovka, the simulated evolution of temperature, δ 18 O and, to a smaller extent, precipitation during the last 50 years is synchronous with model results averaged over all of western Siberia, suggesting that this site will be representative to monitor future isotopic changes in the entire region.

Links between central Greenland stable isotopes, blocking and extreme climate variability over Europe at decadal to multidecadal time scales

“…The correlation decreases to +0.60 if the blocking index is evaluated for (80°W-20°E) as in the case of observations. Correlation coefficients of similar magnitudes between the NAO index and δ 18 O over Europe in the ECHAM5-wiso simulations are reported by Butzin et al (2014) and more recently by Comas-Bru et al (2016).…”

“…Roeckner et al 2006). Details related to the stable isotope module of ECHAM5-wiso model can be found in Werner et al (2011 and Butzin et al (2014). A horizontal model resolution of T106 in spectral space (horizontal grid size of approximately 1.125° × 1.125°), and a vertical resolution of 31 levels on hybrid sigmapressure coordinates were considered in this ECHAM5-wiso simulation.…”

“…In this study the outputs of ECHAM5-wiso simulation Butzin et al 2014) were used to identify the atmospheric circulation patterns associated with central Greenland stable isotope variability. ECHAM5-wiso is the isotope-enabled version of the atmospheric general circulation model ECHAM5 (e.g.…”

To what extent could water isotopic measurements help us understand model biases in the water cycle over Western Siberia

“…As for LMDZ, the European Centre Hamburg Model (ECHAM) model was already compared to the same satellite data sets and showed a good capacity for simulating the observed spatial variations (Butzin et al, 2014). To put the LMDZ results into a broader context, we compare them with those of other model simulations from the SWING2 archive (Fig.…”

Lagrangian process attribution of isotopic variations in near-surface water vapour in a 30-year regional climate simulation over Europe

“…The grid spacing is 0.25 • in the horizontal and between 16 and 2808 m in the vertical, with 40 terrain-following model levels. Initial and boundary conditions are provided by a nudged historical isotope simulation (Butzin et al, 2014) performed with the isotope-enabled European Centre Hamburg Model (ECHAMwiso; Werner et al, 2011) at T106 horizontal resolution and on 31 vertical levels. COSMOiso runs freely inside the model domain.…”