EURO‐CORDEX regional climate model analysis for the Greater Alpine Region: Performance and expected future change

Abstract

Simulations from 13 highly resolved regional climate models run within the Coordinated Downscaling Experiment initiative at 0.11 ∘ resolution with boundary forcings from five different Coupled Model Intercomparison Project Phase 5 global models are employed to derive future climate change signal for the Greater Alpine Region (GAR) and four smaller investigation areas. Evaluation statistics include mean temperature and precipitation, frequency of days with precipitation over 1 mm and over 15 mm, 90% quantile of the frequency distribution, and maximum number of consecutive dry days. The evaluation for the period from 1971 to 2000 indicates that the models reproduce spatial seasonal precipitation patterns. In general, the simulations underestimate the seasonal mean temperature and overestimate the mean precipitation values. In GAR the ensemble seasonal mean temperature bias ranges from −0.8 to −1.9 ∘ C. The bias in precipitation varies between +14.8% in summer and +41.6% in the winter season. Larger errors are found for other statistics and in the investigated regions. In general, no significant gains in the quality of reproduction of the observed precipitation and temperature statistics compared to previous experiments can be identified. The temperature calculations for 2071-2100 related to the period from 1971 to 2000 in the GAR area show ensemble mean increases in the seasonal mean 2 m temperature of 2.5 ∘ C in fall and winter, 2.4 ∘ C in summer, and 1.9 ∘ C in spring. In the same area, precipitation is simulated to increase up to 12.3% in winter and 5.7% in spring. Only minor changes of the ensemble mean are predicted with +2.3% in fall and −1.7% in summer.

Future snowfall in the Alps: projections based on the EURO-CORDEX regional climate models

“…Kotlarski et al, 2014;Smiatek et al, 2016), and one has to expect that the separated snowfall amounts are biased too. This would especially hamper the interpretation of absolute climate change signals of the considered snow indices.…”

“…Rajczak et al, 2017;Smiatek et al, 2016), which in principle could lead to higher snowfall amounts. (2) Temperatures are projected to considerably rise throughout the year (e.g.…”

“…(2) Temperatures are projected to considerably rise throughout the year (e.g. Gobiet et al, 2014;Smiatek et al, 2016;Steger et al, 2013) with the general effect of a decreasing snowfall frequency and fraction, thus potentially leading to a reduction in overall snowfall amounts. Separating the above two competing factors is one of the targets of the current study.…”

Projected cryospheric and hydrological impacts of 21st century climate change in the Ötztal Alps (Austria) simulated using a physically based approach

“…In lower-elevated catchments on the other hand, projected changes in precipitation exhibit a larger impact on changes in runoff (Horton et al, 2006). Besides a projected future increase in winter precipitation on which most current climate projections agree on, future changes in precipitation over the Alpine region are however highly uncertain (Gobiet et al, 2014;Smiatek et al, 2016). Consequently, future trends in total annual streamflow volume for purely snowmelt-dominated catchments are also uncertain, as changes in precipitation might (over)compensate for increased evaporation rates due to higher temperatures.…”

European climate change at global mean temperature increases of 1.5 and 2 °C above pre-industrial conditions as simulated by the EURO-CORDEX regional climate models

“…Kotlarski et al, 2014;Prein et al, 2015). Other studies describing evaluation of different important near-surface variables in 30 the EURO-CORDEX RCMs in the recent past climate include those of Smiatek et al (2016); Knist et al (2016) and Frei et al (2017).…”