Identification of possible dynamical drivers for long-term changes in temperature and rainfall patterns over Europe
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ORIGINAL PAPER
Identification of possible dynamical drivers for long-term changes in temperature and rainfall patterns over Europe Peter Hoffmann1
· Arne Spekat1
Received: 25 February 2020 / Accepted: 3 September 2020 © The Author(s) 2020
Abstract This study looks into the question to what extent long-term change patterns of observed temperature and rainfall over Europe can be attributed to dynamical causes, in other words: Are the observed changes due to a change in frequency of the patterns or have the patterns’ dynamical properties changed? By using a combination of daily meteorological data and a European weather-type classification, the long-term monthly mean temperature and precipitation were calculated for each weathertype. Subsequently, the observed weather-type sequences were used to construct analogue time series for temperature and precipitation which only include the dynamical component of the long-term variability since 1961. The results show that only a fraction of about 20% of the past temperature rise since 1990, which for example amounted to 1 ◦ C at the Potsdam Climate Station can be explained by dynamical changes, i.e. most of the weather-types have become warmer. Concerning long-term changes of seasonal rainfall patterns, a fraction of more than 60% is considerably higher. Moreover, the results indicate that for rainfall compared with temperature, the decadal variability and trends of the dynamical component follow the observed ones much stronger. Consequently, most of the explained seasonal rainfall variances can be linked to changes in weather-type sequences in Potsdam and over Europe. The dynamical contribution to long-term changes in annual and seasonal rainfall patterns dominates due to the fact that the alternation of wet and dry weather-types (e.g. the types Trough or High pressure over Central Europe), their frequencies and duration has significantly changed in the last decades.
1 Introduction The main trigger for average weather as well as extreme events like rainfall of high intensity or duration, heat waves and severe storms is specific synoptic patterns (e.g. Donat et al. 2009; Stucki et al. 2012; Hoy et al. 2013; Kornhuber et al. 2019). The sea level pressure (surface), the geopotential height at 500 hPa (middle troposphere) and the meridional wind velocity at 300 hPa (upper troposphere) are
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00704-020-03373-3) contains supplementary material, which is available to authorized users. Peter Hoffmann
[email protected] 1
Potsdam Institute for Climate Impacts Research, Research Domain: Climate Resilience, Telegrafenberg A31, 14412 Potsdam, Germany
essential meteorological variables for the characterization and categorization of the synoptical situation over a region such as the North-Atlantic and Europe (e.g. Hess and Brezowsky 1977; James 2007; Huth et al. 2008). Reported changes in occurrence frequencies and durations of weather patterns (e.g. Kysel´y 2008; Werner et al. 2008; Cah
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