Changes in extreme nival conditions in Poland during the second half of the 20th century

Abstract

The two main objectives of this study are: 1. to assess the scale of extreme nival conditions in Poland; 2. to provide a fragmentary, regional verification of the IPCC thesis of the increasing frequency of extreme atmospheric phenomena during recent decades, by the estimation of extreme nival conditions tendencies in the second half of the 20 th century. The daily data of snow cover depth in 12 meteorological stations in Poland, for the period 1954-2001, were analysed. A winter season with extreme nival conditions is the season, when the snow cover duration value and/or the maximum seasonal snow cover depth value, was of the empirical probability of < 10 % (a season of extremely short duration and/or thin snow cover) or > 90 % (a season of extremely long duration and/or thick snow cover). A slight negative, usually statistically insignificant, trend was found for characteristics concerning extremely abundant snow cover, i.e.: the seasonal number of days with snow cover of a considerable depth; the 90th percentile value of the daily snow cover depth for the period from December 1 to February 28; the seasonal maximum of a 24-hour increase in the snow cover depth (except for northern Poland); the seasonal number of days with a 24-hour increase in the snow cover depth of ≥ 10 cm. At the same time, since the 1970's the scarce snow cover (i.e. of the empirical probability < 10 %) has been observed much more frequently than before. The above mentioned IPCC thesis has been confirmed towards the extremely low snow cover values in Poland. Zusammenfassung Die beiden Hauptziele dieser Veröffentlichung sind: 1. Untersuchung der Größenordnung extremer Schneeverhältnisse in Polen, 2. Verifizierung einer These vom IPCC über die Zunahme der Häufigkeit von extremen meteorologischen Phänomenen in den letzten Jahrzehnten anhand der Tendenz zu extremen Schneebedingungen in der zweiten Hälfte des 20. Jahrhunderts. Es wurden Tageswerte der Schneedeckenhöhe an 12 meteorologischen Stationen für das Gebiet Polens in der Zeit von 1954-2001 analysiert. Als Winterhalbjahr mit extremen Schneebedingungen wurde ein Halbjahr bezeichnet, in dem die Schneebedeckung und/oder die maximale Höhe der Schneedecke eine empirische Wahrscheinlichkeit von < 10 % aufweist (Winterhalbjahr mit extrem kurzer Schneebedeckung und/oder extrem geringer Schneedecke) bzw. > 90 % erreicht (Winterhalbjahr mit extrem langer Schneebedeckung und/oder hoher Schneedecke). Ein schwach negativer-in den meisten Fällen statistisch nicht signifikanter-Trend wurde bei folgenden charakteristischen Größen der Schneebedeckung festgestellt: Anzahl der Tage pro Winterhalbjahr mit relevanten Schneedeckenhöhen (≥ 10 cm, ≥ 20 cm, ≥ 50 cm), Tageswerte der Schneedeckenhöhe mit empirischer Wahrscheinlichkeit von ≥ 90 % in der Zeit vom 1. Dezember bis 28. Februar, Maximum des Tageszuwachses der Schneedecke im Winterhalbjahr und Anzahl der Tage mit Tageszuwachs der Schneedecke ≥ 10 cm. Winterhalbjahre mit extrem geringer Schneedecke treten vor allem in der zweiten Hälfte der untersuchten Peri...

Long-term changes in annual maximum snow depth and snowfall in Switzerland based on extreme value statistics

“…80 values), we prefer using a more simplistic model which is already a further step compared to the usual linear trend (of e.g. quantiles) used so far for analysing trends in extreme snow events (Kunkel et al 2009;Falarz 2008).…”

“…It has been quite widely used for climate data such as wind speed (Hundecha et al 2008), precipitation (Beguería et al 2010), temperature (Brown et al 2008), etc. However, to our knowledge, it has never been applied to snow events, for which so far only the temporal evolution of events of fixed magnitude and of fixed quantiles have been studied (Kunkel et al 2009;Falarz 2008). The main difference to the non-stationary extreme value method is that only fixed statistics (e.g.…”

The European mountain cryosphere: a review of its current state, trends, and future challenges

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Recent Change—Terrestrial Cryosphere

“…The occurrence of a positive NAO phase has been shown to contribute to rapid snowmelt events in Polish-German lowlands (southern part of the Baltic Sea drainage basin) (Bednorz 2009), and the location of low-pressure systems over Europe has been shown to be responsible for heavy snowfalls in this region (Bednorz 2008). Extreme SCDs and maximum seasonal snow depth values in Poland during the latter half of the twentieth century were analysed by Falarz (2008) (Fig. 6.4).…”