Anomalously heavy monthly and seasonal precipitation in the Polish Carpathian Mountains and their foreland during the years 1881–2010

Robert Twardosz,Marta Cebulska,Adam Walanus

doi:10.1007/s00704-015-1570-3

Abstract

The paper addresses the frequency, amount and geographic coverage of anomalously heavy precipitation in southern Poland in relation to atmospheric circulation at the monthly and seasonal scales between 1881 and 2010. The Carpathian Mountains and their foreland were selected for the study as an area known for its high precipitation totals and frequent precipitation-triggered natural disasters, such as floods and landslides. Records from 18 stations were used to identify anomalously heavy precipitation (AHP) defined for the purposes of the study, as the top quartile (Q 75 %) plus 1.5 times the interquartile gap (H) of the precipitation total (P ≥ Q 75 % + 1.5H). The study found that most cases of AHP were recorded at one single station each. This suggests that, in addition, to the influence of circulation, local factors also play a major role in the formation of particularly heavy precipitation. The greatest absolute anomalously high precipitation totals were recorded in two disparate parts of the study area: (i) its western part exposed to wet air masses from over the Atlantic Ocean brought in by the dominant western circulation in the temperate zone and (ii) elevated parts of its south-eastern part. Two months with AHP (AHP months) occurred over the entire area (18 stations) in May 1940 and 2010. The latter case had both the greatest absolute totals (over 500 mm) and relative totals defined as their ratio to the long-term average (500 %), and it triggered a catastrophic flood in the Upper Vistula basin.

Highlights

Periodic surpluses or deficits of precipitation may be regarded as dangerous meteorological and hydrological events
This study focused on months with anomalously heavy precipitation and seasons, but some consideration was given to years with anomalously heavy precipitation
It was demonstrated that while anomalously heavy precipitation (AHP) occurred in all months, in seasons and in entire years, they were infrequent

Summary

Introduction

Periodic surpluses or deficits of precipitation may be regarded as dangerous meteorological and hydrological events. If sufficiently large, they can have a significant impact on numerous areas of human activity. They can have a significant impact on numerous areas of human activity Over long spells, they lead to excessive water surpluses or acute droughts. The temperate European climate, mainly influenced by the strong variability of atmospheric circulation, is characterised by the occurrence of long spells of various types of weather, including heavy precipitation, heat waves and cold periods (Twardosz and Kossowska-Cezak 2015). Räisänen (2005) uses ensemble averages to claim that the variability increases slightly in most areas, so that the contrast between the high and low precipitation extremes grows larger with increasing CO2

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Conclusion