Abstract
Abstract. Severe winter storms in combination with precipitation extremes pose a
serious threat to Europe. Located at the southeastern exit of the North
Atlantic's storm track, European coastlines are directly exposed to impacts
by high wind speeds, storm floods and coastal erosion. In this study we
analyze potential changes in simulated winter storminess and extreme
precipitation, which may occur under 1.5 or 2 ∘C warming scenarios.
Here we focus on a first simulation suite of the atmospheric model CAM5
performed within the HAPPI project and evaluate how changes of the horizontal
model resolution impact the results regarding atmospheric pressure, storm
tracks, wind speed and precipitation extremes. The comparison of CAM5 simulations with different resolutions indicates that
an increased horizontal resolution to 0.25∘ not only refines
regional-scale information but also improves large-scale atmospheric
circulation features over the Euro-Atlantic region. The zonal bias in monthly pressure at mean sea level
and wind fields, which is typically found in low-resolution models, is
considerably reduced. This allows us to analyze potential changes in
regional- to local-scale extreme wind speeds and precipitation in a more
realistic way. Our analysis of the future response for the 2 ∘C warming scenario
generally confirms previous model simulations suggesting a poleward shift
and intensification of the meridional circulation in the Euro-Atlantic
region. Additional analysis suggests that this shift occurs mainly after
exceeding the 1.5 ∘C global warming level, when the midlatitude
jet stream manifests a strengthening northeastward. At the same time, this
northeastern shift of the storm tracks allows an intensification and
northeastern expansion of the Azores high, leading to a tendency of less
precipitation across the Bay of Biscay and North Sea. Regions impacted by the strengthening of the midlatitude jet, such as the
northwestern coasts of the British Isles, Scandinavia and the Norwegian Sea,
and over the North Atlantic east of Newfoundland, experience an increase in
the mean as well as daily and sub-daily precipitation, wind extremes and
storminess, suggesting an important influence of increasing storm activity in
these regions in response to global warming.
Subject
General Earth and Planetary Sciences
Cited by
23 articles.
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