Changing seasonality of moderate and extreme precipitation events in the Alps
<p>The intensity of precipitation events is expected to increase in the future. The rate of increase depends on the strength or rarity of the events; very strong and rare events tend to follow the Clausius–Clapeyron relation, whereas weaker events or precipitation averages increase at a sma...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-07-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://www.nat-hazards-earth-syst-sci.net/18/2047/2018/nhess-18-2047-2018.pdf |
| _version_ | 1819261637873369088 |
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| author | S. Brönnimann S. Brönnimann J. Rajczak J. Rajczak E. M. Fischer C. C. Raible C. C. Raible M. Rohrer M. Rohrer C. Schär |
| author_facet | S. Brönnimann S. Brönnimann J. Rajczak J. Rajczak E. M. Fischer C. C. Raible C. C. Raible M. Rohrer M. Rohrer C. Schär |
| author_sort | S. Brönnimann |
| collection | DOAJ |
| description | <p>The intensity of precipitation events is expected to increase in the future.
The rate of increase depends on the strength or rarity of the events; very
strong and rare events tend to follow the Clausius–Clapeyron relation,
whereas weaker events or precipitation averages increase at a smaller rate
than expected from the Clausius–Clapeyron relation. An often overlooked
aspect is seasonal occurrence of such events, which might change in the
future. To address the impact of seasonality, we use a large ensemble of
regional and global climate model simulations, comprising tens of thousands
of model years of daily temperature and precipitation for the past, present,
and future. In order to make the data comparable, they are quantile mapped to
observation-based time series representative of the Aare catchment in
Switzerland. Model simulations show no increase in annual maximum 1-day
precipitation events (Rx1day) over the last 400 years and an increase of
10 %–20 % until the end of the century for a strong (RCP8.5) forcing
scenario. This fits with a Clausius–Clapeyron scaling of temperature at the
event day, which increases less than annual mean temperature. An important
reason for this is a shift in seasonality. Rx1day events become less frequent
in late summer and more frequent in early summer and early autumn, when it is
cooler. The seasonality shift is shown to be related to summer drying. Models
with decreasing annual mean or summer mean precipitation show this behaviour
more strongly. The highest Rx1day per decade, in contrast, shows no change in
seasonality in the future. This discrepancy implies that decadal-scale
extremes are thermodynamically limited; conditions conducive to strong events
still occur during the hottest time of the year on a decadal scale. In
contrast, Rx1day events are also limited by other factors. Conducive
conditions are not reached every summer in the present, and even less so in
the future. Results suggest that changes in the seasonal cycle need to be
accounted for when preparing for moderately extreme precipitation events and
assessing their socio-economic impacts.</p> |
| first_indexed | 2024-12-23T19:44:58Z |
| format | Article |
| id | doaj.art-37c5f3934ad345f1b80ca9c8951518f3 |
| institution | Directory Open Access Journal |
| issn | 1561-8633 1684-9981 |
| language | English |
| last_indexed | 2024-12-23T19:44:58Z |
| publishDate | 2018-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Natural Hazards and Earth System Sciences |
| spelling | doaj.art-37c5f3934ad345f1b80ca9c8951518f32022-12-21T17:33:33ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812018-07-01182047205610.5194/nhess-18-2047-2018Changing seasonality of moderate and extreme precipitation events in the AlpsS. Brönnimann0S. Brönnimann1J. Rajczak2J. Rajczak3E. M. Fischer4C. C. Raible5C. C. Raible6M. Rohrer7M. Rohrer8C. Schär9Oeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandInstitute of Geography, University of Bern, Bern, SwitzerlandInstitute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerlandnow at: Federal Office of Meteorology and Climatology MeteoSwiss, 8058 Zurich Airport, Zurich, SwitzerlandInstitute for Atmospheric and Climate Science, ETH Zurich, Zürich, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandClimate and Environmental Physics, Physics Institute, University of Bern, Bern, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandInstitute of Geography, University of Bern, Bern, SwitzerlandInstitute for Atmospheric and Climate Science, ETH Zurich, Zürich, Switzerland<p>The intensity of precipitation events is expected to increase in the future. The rate of increase depends on the strength or rarity of the events; very strong and rare events tend to follow the Clausius–Clapeyron relation, whereas weaker events or precipitation averages increase at a smaller rate than expected from the Clausius–Clapeyron relation. An often overlooked aspect is seasonal occurrence of such events, which might change in the future. To address the impact of seasonality, we use a large ensemble of regional and global climate model simulations, comprising tens of thousands of model years of daily temperature and precipitation for the past, present, and future. In order to make the data comparable, they are quantile mapped to observation-based time series representative of the Aare catchment in Switzerland. Model simulations show no increase in annual maximum 1-day precipitation events (Rx1day) over the last 400 years and an increase of 10 %–20 % until the end of the century for a strong (RCP8.5) forcing scenario. This fits with a Clausius–Clapeyron scaling of temperature at the event day, which increases less than annual mean temperature. An important reason for this is a shift in seasonality. Rx1day events become less frequent in late summer and more frequent in early summer and early autumn, when it is cooler. The seasonality shift is shown to be related to summer drying. Models with decreasing annual mean or summer mean precipitation show this behaviour more strongly. The highest Rx1day per decade, in contrast, shows no change in seasonality in the future. This discrepancy implies that decadal-scale extremes are thermodynamically limited; conditions conducive to strong events still occur during the hottest time of the year on a decadal scale. In contrast, Rx1day events are also limited by other factors. Conducive conditions are not reached every summer in the present, and even less so in the future. Results suggest that changes in the seasonal cycle need to be accounted for when preparing for moderately extreme precipitation events and assessing their socio-economic impacts.</p>https://www.nat-hazards-earth-syst-sci.net/18/2047/2018/nhess-18-2047-2018.pdf |
| spellingShingle | S. Brönnimann S. Brönnimann J. Rajczak J. Rajczak E. M. Fischer C. C. Raible C. C. Raible M. Rohrer M. Rohrer C. Schär Changing seasonality of moderate and extreme precipitation events in the Alps Natural Hazards and Earth System Sciences |
| title | Changing seasonality of moderate and extreme precipitation events in the Alps |
| title_full | Changing seasonality of moderate and extreme precipitation events in the Alps |
| title_fullStr | Changing seasonality of moderate and extreme precipitation events in the Alps |
| title_full_unstemmed | Changing seasonality of moderate and extreme precipitation events in the Alps |
| title_short | Changing seasonality of moderate and extreme precipitation events in the Alps |
| title_sort | changing seasonality of moderate and extreme precipitation events in the alps |
| url | https://www.nat-hazards-earth-syst-sci.net/18/2047/2018/nhess-18-2047-2018.pdf |
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