Spatio-temporal changes in atmospheric precipitation over south-western Poland between the periods 1891–1930 and 1981–2010

Abstract

In this paper, we quantify the changes in precipitation distribution in south-western Poland between the periods 1891-1930 and 1981-2010. The average monthly precipitation totals available for 368 and 245 stations, respectively, are spatially interpolated and processed to calculate maps of differences and pluvial continentality indices for both periods. The maps are analysed against changes in atmospheric circulation and take into account the potential role of the mountain barrier of the Sudetes. The main findings are (1) winter totals generally increased in conjunction with a higher frequency of zonal circulation; it is more pronounced in the upper parts of the Sudetes due to orographic effects; (2) a decreased frequency of zonal circulation together with an increased frequency of southern flows has likely led to the reduction of precipitation in spring and autumn. These changes have led to a significant modification of the region's pluvial regime, mostly by decreasing continentality features (especially in the Sudetes and the western lowlands). In addition, the strong sheltering influence of the mountain barrier is observed, driving the preservation or even the enhancement of the continental pluvial characteristics in the north-eastern to eastern foregrounds of the Sudetes. This leads to the conclusion that in areas where long-term observed trends or future projections of precipitation are ambiguous, there may occur significant modifications in regional characteristics, especially as a result of changes in atmospheric circulation modified by local orography.

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“…However, as we verified numerically, the system is globally stable because of the presence of the limit cycle, which is an actual invariant manifold of the system and result from the interplay between attraction and repellion of the equilibrium point along the three coordinate axes X,Y,Z. The stability properies of the limit cycle could be well investigated by mean of Floquet theory (Strogatz 2018), which is however not object of the present work. The significance and implications for the slow component of the system dynamical properties presented above will be discussed in the next section.…”

“…The corresponding dynamical system can sometimes be reconstructed starting from observations (Baake et al 1992;Eisenhammer et al 1991;Judd and Mees 1995;Irving and Dewson 1997;Perona et al 2000;Perona et al 2001). Most of such techniques are today included in machine learning approaches (Czernecki et al 2018;Pilguj et al 2019;Szymanowski et al 2019).…”

“…In order to inquire the stability of equilibrium points we performed a linear stability analysis, whose details can be found in any analytical mechanics books, e.g. see Strogatz (2018) Here it suffices to recall that the main steps of the linear stability analysis are to first linearize the model (Eq. (5)) and then to calculate the corresponding eigenvalues of the matrix of the first order partial derivatives (Jacobian matrix) at each equilibrium point.…”

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