Simulation of δ¹⁸O in precipitation by the regional circulation model REMO_iso

Abstract

Abstract:The first results of a regional circulation model REMO iso fitted with water isotope diagnostics are compared with various isotope series from central Europe. A 2 year case study is conducted from March 1997 to February 1999 centred over Europe, analysing daily and monthly measurements. Isotope signals over Europe are dominated by the typical isotopic effects such as temperature, continental and altitude effects, both on annual and seasonal scales. These well-known isotopic effects are successfully reproduced by REMO iso , using two different boundary data sets. In a first simulation, the European Centre for Medium-range Weather Forecasts (ECMWF) analyses serve as boundary conditions, where water isotopes were parameterized by a simple temperature dependence. In a second simulation, boundary conditions both for climatic and isotopic variables are taken from the ECHAM iso general circulation model output. The comparison of both simulations shows a very high sensitivity of the simulated υ 18 O signal to boundary conditions. The ECMWF-nested simulation shows an average offset of 4Ð5‰ in mean υ18 O values and exaggerated seasonal amplitude. The ECHAM-nested simulation represents correctly the observed mean υ18 O values, although with a dampened seasonality. REMO iso 's isotope module is further validated against daily υ 18 O measurements at selected stations (Nordeney, Arkona and Hohenpeissenberg) situated in Germany.

Palaeoclimate research in Villars Cave (Dordogne, SW-France)

“…17) which likely yield a lower precipitation δ 18 O above Villars Cave. Simulated rainfall δ 18 O near Villars using the REMO program (Sturm et al, 2005; Pierre Alain Danis and Georg Hoffmann communications) seems to confirm this hypothesis: reconstructed rainfall δ 18 O from 1960 to 2001 yield an average increasing trend of +0.146‰/10 years, then, in order to explain the +0.2‰ difference between the lower and the upper galleries, a theoretical age difference in the rainfall feeding the seepage water is 13.6 years. Tritium measurements on dripping water will eventually confirm this hypothesis.…”

The isotopic composition of precipitation from a winter storm – a case study with the limited-area model COSMO<sub>iso</sub>

“…In order to extend the COSMO model for simulating stable isotopes in the atmospheric water cycle, an approach is adopted similar to previous implementations of isotopes in GCMs and regional models (see again Joussaume et al, 1984;Sturm et al, 2005;Blossey et al, 2010, for examples). A parallel water cycle is introduced that does not affect other model components and is used as a purely diagnostic tool.…”

“…Therefore, isotope physics have also been implemented in limited-area models. Sturm et al (2005) incorporated water isotopes into the regional climate model REMO, which was subsequently used for investigations on long, climatological time scales (e.g., Sturm et al, 2007). Smith et al (2006) and Blossey et al (2010) used cloud resolving models for simulating idealised tropical circulations, focusing on isotope variations in the tropical tropopause layer.…”

Deuterium excess in the atmospheric water vapour of a Mediterranean coastal wetland: regional vs. local signatures

“…In addition, isotope tracers are now often incorporated into climate models (Sturm et al, 2005;Werner et al, 2011;Risi et al, 2012Risi et al, , 2013 in order to improve the representation of landatmosphere interactions and feedbacks. A major challenge is thus to propose robust databases, and associated methodology for data acquisition and interpretation.…”