Future snowfall in the Alps: projections based on the EURO-CORDEX regional climate models
Twenty-first century snowfall changes over the European Alps are assessed based on high-resolution regional climate model (RCM) data made available through the EURO-CORDEX initiative. Fourteen different combinations of global and regional climate models with a target resolution of 12 km and two...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-01-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/1/2018/tc-12-1-2018.pdf |
| Summary: | Twenty-first century snowfall changes over the European Alps are assessed based on
high-resolution regional climate model (RCM) data made available through the
EURO-CORDEX initiative. Fourteen different combinations of global and
regional climate models with a target resolution of 12 km and two
different emission scenarios are considered. As raw snowfall amounts are not
provided by all RCMs, a newly developed method to separate snowfall from
total precipitation based on near-surface temperature conditions and
accounting for subgrid-scale topographic variability is employed. The
evaluation of the simulated snowfall amounts against an observation-based
reference indicates the ability of RCMs to capture the main characteristics
of the snowfall seasonal cycle and its elevation dependency but also reveals
considerable positive biases especially at high elevations. These biases can
partly be removed by the application of a dedicated RCM bias adjustment that
separately considers temperature and precipitation biases.</p><p class="p">Snowfall projections reveal a robust signal of decreasing snowfall amounts
over most parts of the Alps for both emission scenarios. Domain and
multi-model mean decreases in mean September–May snowfall by the end of the
century amount to −25 and −45 % for representative concentration
pathway (RCP) scenarios RCP4.5 and RCP8.5, respectively. Snowfall in
low-lying areas in the Alpine forelands could be reduced by more than
−80 %. These decreases are driven by the projected warming and are
strongly connected to an important decrease in snowfall frequency and
snowfall fraction and are also apparent for heavy snowfall events. In
contrast, high-elevation regions could experience slight snowfall increases
in midwinter for both emission scenarios despite the general decrease in the
snowfall fraction. These increases in mean and heavy snowfall can be
explained by a general increase in winter precipitation and by the fact that,
with increasing temperatures, climatologically cold areas are shifted into
a temperature interval which favours higher snowfall intensities. In general,
percentage changes in snowfall indices are robust with respect to the RCM
postprocessing strategy employed: similar results are obtained for raw,
separated, and separated–bias-adjusted snowfall amounts. Absolute changes,
however, can differ among these three methods. |
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| ISSN: | 1994-0416 1994-0424 |