Observed changes in extreme precipitation in Poland: 1991–2015 versus 1961–1990
Observed changes in extreme precipitation in Poland: 1991-2015 versus 1961-1990
Iwona Pińskwar 0
Adam Choryński 0
Dariusz Graczyk 0
Zbigniew W. Kundzewicz 0
0 Potsdam Institute for Climate Impact Research , Potsdam , Germany
1 Iwona Pińskwar
Several episodes of extreme precipitation excess and extreme precipitation deficit, with considerable economic and social impacts, have occurred in Europe and in Poland in the last decades. However, the changes of related indices exhibit complex variability. This paper analyses changes in indices related to observed abundance and deficit of precipitated water in Poland. Among studied indices are maximum seasonal 24-h precipitation for the winter half-year (Oct.-March) and the summer half-year (Apr.-Sept.), maximum 5-day precipitation, maximum monthly precipitation and number of days with intense or very intense precipitation (respectively, in excess of 10 mm or 20 mm per day). Also, the warm-seasonal maximum number of consecutive dry days (longest period with daily precipitation below 1 mm) was examined. Analysis of precipitation extremes showed that daily maximum precipitation for the summer half-year increased for many stations, and increases during the summer half-year are more numerous than those in the winter half-year. Also, analysis of 5-day and monthly precipitation sums show increases for many stations. Number of days with intense precipitation increases especially in the north-western part of Poland. The number of consecutive dry days is getting higher for many stations in the summer half-year. Comparison of these two periods: colder 19611990 and warmer 1991-2015, revealed that during last 25 years most of statistical indices, such as 25th and 75th percentiles, median, mean and maximum are higher. However, many changes discussed in this paper are weak and statistically insignificant. The findings reported in this paper challenge results based on earlier data that do not include 2007-2015.
1 Introduction
According to the Clausius-Clapeyron law, there is more room
for water vapour in the warming atmosphere; hence, potential
for intense precipitation grows. The 5th Assessment Report of
the
IPCC (2014)
states that it is very likely that global
nearsurface and tropospheric air humidity has increased since the
1970s. Also, frequency and intensity of heavy precipitation
events has likely increased in North America and Europe, as
a result of anthropogenic forcing, which leads to an
intensification of the water cycle. Existing analyses of trends in
hydrometeorological data cover large scales, that is the global
scale: e.g.
Groisman et al. 2005
;
Alexander et al. 2006
;
Donat
et al. 2013
; the European scale: e.g.
Zolina et al. 2010
; Zolina
Institute for Agricultural and Forest Environment, Polish Academy
of Sciences, Bukowska 19, 60-809 Poznań, Poland
task to enable better interpretation of possible future trends.
Increase of the extreme abundance of water has potential
impacts, including floods, erosion, flash floods and inundation.
Deficits of water may affect water resources, agriculture and
ecosystems.
Several episodes of extreme precipitation excess and
extreme precipitation deficit, leading to dramatic floods and
droughts, with considerable economic and social impacts,
have occurred in Europe in the last decades. Major floods
occurred in the decade of the 1990s, such as in 1993 and
1995 (the basins of the River Rhine and its tributaries), in
1994 (the Mediterranean region) and in 1997 (Central
Europe). In the twenty-first century, serious floods occurred
in 2000 in Western Europe (UK, Italy, France and
Switzerland), in 2005, 2007 and 2010. The most severe floods
with the absolute record of annual flood loss in Europe,
exceeding €20 billion (nominal value, unadjusted for inflation)
were observed in August 2002
(Kundzewicz et al. 2013)
. One
year after these great floods, in the summer of 2003, many
parts of Europe experienced severe droughts and heat waves.
The summer of 2010, exceptionally warm and dry in Eastern
Europe and large parts of Russia, was more severe than the
hottest summer of 2003 because of higher amplitude and
spatial extent. During that time, extensive fires across western
Russia occurred. According to projections, these anomalously
warm and dry episodes are recognised as summers which are
likely to occur more frequently in the later decades of the
twenty-first century
(Beniston 2004, Barriopedro et al. 2011)
.
In Poland, destructive floods as a result of abundant rainfall
with high material damage and tens of fatalities occurred in
1970, 1997, 2001 and 2010. The most severe floods of 1997
and 2010 were preceded by very intense and long-lasting
precipitation over large areas, so in consequence, large parts of
Poland were flooded
(Kundzewicz et al. 2012)
. Noticeable is
an increasing number of local floods in urban areas (flash
floods) caused by intensive rainfall. In 2017, several cities in
Poland were affected by abundan (...truncated)