scholarly journals Past long-term summer warming over western Europe in new generation climate models: role of large-scale atmospheric circulation

2020 ◽  
Vol 15 (8) ◽  
pp. 084038
Author(s):  
Julien Boé ◽  
Laurent Terray ◽  
Marie-Pierre Moine ◽  
Sophie Valcke ◽  
Alessio Bellucci ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Western Europe ◽  
Climate Models ◽  
Summer Warming ◽  
New Generation ◽  
Large Scale Atmospheric Circulation

Opposite trends of sea-breeze speeds and gusts in Eastern Iberian Peninsula, 1961-2019

2021 ◽  
Author(s):  
Shalenys Bedoya-Valestt ◽  
Cesar Azorin-Molina ◽  
José A. Guijarro ◽  
Victor J. Sanchez-Morcillo
Keyword(s):  
Wind Speed ◽  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
Air Temperature ◽  
Large Scale ◽  
Sea Breeze ◽  
Sea Breezes ◽  
Long Term Trends ◽  
Large Scale Atmospheric Circulation

<p>Long-term trends of local winds such as sea breezes have been less addressed in climate research, despite their impacts on broad environmental and socioeconomic spheres, such as weather and climate, agriculture and hydrology, wind-power industry, air quality or even human health, among many others. In a warming climate, sea breezes could be affected by changes on air temperature, as these onshore winds are thermally-driven by gradients between the sea-land air, but also by ocean-atmosphere oscillations or changes in large-scale atmospheric circulation. In the last few decades, advances in wind trends studies evidenced a recovery in global wind stilling during the last 10 years, and differences in the sign-magnitude of wind speed trends were found at seasonal-scale, suggesting the hypothetic effect of the reinforcement of local wind circulations in the warm seasons.</p><p>In this study, we analyze for the first time the long-term trends, multidecadal variability and possible drivers of the sea-breeze speeds and gusts in Eastern Iberian Peninsula during the last 58 years (1961-2019), using homogenized wind speed and gusts data from 16 meteorological stations. To identify potential sea breeze episodes, we developed a robust automated method based on alternative criteria. Our results suggest a decoupling between the declining sea-breeze speeds and the strengthening of the maximum gusts for much of the 1961-2019 period at annual, seasonal and monthly scales, but differences based on locations were also found. Because sea breeze changes can be driven by multiple complex factors (i.e. land use changes, land-sea air temperature gradient, complex orography, etc.), the attribution of causes is challenging. To better understand the causes behind the opposite trends between sea-breeze speeds and gusts, we investigate the effect of e.g. the changes in large-scale atmospheric circulation or physical-local factors.</p>

scholarly journals Winter extreme weather in EURO-CORDEX climate models and their links to large-scale atmospheric circulation

2021 ◽  
Author(s):  
Eva Plavcová ◽  
Ondřej Lhotka ◽  
Jan Stryhal
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Climate Models ◽  
Climate Model ◽  
Regional Scale ◽  
Global Climate Models ◽  
Wind Gust ◽  
Climate Change Scenarios ◽  
Winter Weather ◽  
Large Scale Atmospheric Circulation

<p>Regional Climate Models (RCMs) are powerful tools to study changes in the climate system on the regional scale. However, the reliability of their simulations has been considerably limited by the longstanding issue that climate models often fail to reproduce various aspects of the historical climate. In our study, we analyse how RCMs from the EURO-CORDEX project are able to reproduce extreme winter weather. We analyse temporal and spatial characteristics of extreme wind gust, extremely cold temperature, and extreme precipitation. Model outputs are validated against observed data from the European gridded observational database (EOBS) and the novel ERA5 reanalysis. We focus on the Central European domain (defined between 48–52°N and 10–19°E) over the 1979 – 2017 period. We investigate a set of 9 simulations of 3 different RCMs driven by 3 different global climate models which allow us to analyse the influence of driving data on the RCM’s performance. Since local climate elements are relatively tightly linked to a large-scale atmospheric circulation over Europe in winter, we also evaluate the ability of RCMs to reproduce the atmospheric circulation and its links to selected high-impact winter weather in detail. We use the classification of circulation based on the method of Sammon mapping. Investigation of these links can lead to better physical understanding of the climate and to the identification of inadequacies in simulated characteristics of the studied events. All of this is an important step forward in further improving the models and enhancing the credibility of climate change scenarios based on climate model simulations.</p>

scholarly journals Projections of northern hemisphere extratropical climate underestimate internal variability and associated uncertainty

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Christopher H. O’Reilly ◽  
Daniel J. Befort ◽  
Antje Weisheimer ◽  
Tim Woollings ◽  
Andrew Ballinger ◽  
...  
Keyword(s):  
Climate Variability ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Climate Models ◽  
Regional Climate ◽  
Coupled Model ◽  
Internal Variability ◽  
Uncertainty Range ◽  
Coupled Climate Models ◽  
Large Scale Atmospheric Circulation

AbstractInternal climate variability will play a major role in determining change on regional scales under global warming. In the extratropics, large-scale atmospheric circulation is responsible for much of observed regional climate variability, from seasonal to multidecadal timescales. However, the extratropical circulation variability on multidecadal timescales is systematically weaker in coupled climate models. Here we show that projections of future extratropical climate from coupled model simulations significantly underestimate the projected uncertainty range originating from large-scale atmospheric circulation variability. Using observational datasets and large ensembles of coupled climate models, we produce synthetic ensemble projections constrained to have variability consistent with the large-scale atmospheric circulation in observations. Compared to the raw model projections, the synthetic observationally-constrained projections exhibit an increased uncertainty in projected 21st century temperature and precipitation changes across much of the Northern extratropics. This increased uncertainty is also associated with an increase of the projected occurrence of future extreme seasons.

scholarly journals Extreme associated functions: optimally linking local extremes to large-scale atmospheric circulation structures

2007 ◽  
Vol 7 (5) ◽  
pp. 14433-14460 ◽  
Author(s):  
D. Panja ◽  
F. M. Selten
Keyword(s):  
Time Series ◽  
The Netherlands ◽  
Atmospheric Circulation ◽  
Large Scale ◽  
Climate Models ◽  
Weather Extremes ◽  
Pressure System ◽  
Reanalysis Dataset ◽  
Local Weather ◽  
Large Scale Atmospheric Circulation

Abstract. We present a new statistical method to optimally link local weather extremes to large-scale atmospheric circulation structures. The method is illustrated using July–August daily mean temperature at 2 m height (T2m) time-series over the Netherlands and 500 hPa geopotential height (Z500) time-series over the Euroatlantic region of the ECMWF reanalysis dataset (ERA40). The method identifies patterns in the Z500 time-series that optimally describe, in a precise mathematical sense, the relationship with local warm extremes in the Netherlands. Two patterns are identified; the most important one corresponds to a blocking high pressure system leading to subsidence and calm, dry and sunny conditions over the Netherlands. The second one corresponds to a rare, easterly flow regime bringing warm, dry air into the region. The patterns are robust; they are also identified in shorter subsamples of the total dataset. The method is generally applicable and might prove useful in evaluating the performance of climate models in simulating local weather extremes.

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