Analysis of Sub-Daily Precipitation for the Pannex Region
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atmosphere Article Analysis of Sub-Daily Precipitation for the PannEx Region Monika Lakatos 1,*, Olivér Szentes 1, Ksenija Cindri´cKalin 2, Irena Nimac 2, Katja Kozjek 3, Sorin Cheval 4 , 4 4 5,6 5 7 7 Alexandru Dumitrescu , Adrian Iras, oc , Petr Stepanek , Aleš Farda , Peter Kajaba , Katarína Mikulová , Dragan Mihic 8, Predrag Petrovic 8, Barbara Chimani 9 and David Pritchard 10 1 Hungarian Meteorological Service, 1024 Budapest, Hungary; [email protected] 2 Croatian Meteorological and Hydrological Service, 10000 Zagreb, Croatia; [email protected] (K.C.K.); [email protected] (I.N.) 3 Slovenian Environment Agency, 1000 Ljubljana, Slovenia; [email protected] 4 National Meteorological Administration, 013686 Bucharest, Romania; [email protected] (S.C.); [email protected] (A.D.); [email protected] (A.I.) 5 Global Change Research Institute, Czech Academy of Sciences, 603 00 Brno, Czech Republic; [email protected] (P.S.); [email protected] (A.F.) 6 Czech Hydrometeorological Institute, 616 67 Brno, Czech Republic 7 Slovak Hydrometeorological Institute, 833 15 Bratislava, Slovakia; [email protected] (P.K.); [email protected] (K.M.) 8 Republic Hydrometeorological Service of Serbia, 11030 Beograd, Serbia; [email protected] (D.M.); [email protected] (P.P.) 9 Zentralanstalt für Meteorologie und Geodynamik, 1190 Wien, Austria; [email protected] 10 School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK; [email protected] * Correspondence: [email protected]; Tel.: +36-1-346-4725 Citation: Lakatos, M.; Szentes, O.; Abstract: The PannEx is a GEWEX-initiated, community driven research network in the Pannonian Cindri´cKalin, K.; Nimac, I.; Kozjek, Basin. One of the main scientific issues to address in PannEx is the investigation of precipitation K.; Cheval, S.; Dumitrescu, A.; Irasoc, , extremes. Meteorological Services in the PannEx area collected the hourly precipitation data and A.; Stepanek, P.; Farda, A.; et al. commonly used a computer program, which was developed in the INTENSE project, to produce Analysis of Sub-Daily Precipitation a set of global hydro-climatic indices. Calculations are carried out on data aggregated 1-, 3- and for the PannEx Region. Atmosphere 2021, 12, 838. https://doi.org/ 6-h intervals. Selected indices are analyzed in this paper to assess the general climatology of the 10.3390/atmos12070838 short-term precipitation in the Pannonian basin. The following indices are illustrated on maps and graphs: the annual mean and maxima of 1-h, 3-h and 6-h sums, the count of 3-hr periods greater Academic Editor: than 20 mm thresholds, the maximum length of wet hours, the timing of wettest hour and the 1-h Adina-Eliza Croitoru precipitation intensity. The seasonal trends of the 1-h precipitation intensity were tested from 1998 to 2019. Analysis of sub-daily precipitation has been limited by the availability of data on a global Received: 20 May 2021 or a regional scale. The international effort made in this work through collaboration in the PannEx Accepted: 21 June 2021 initiative contributes to enlarging the data availability for regional and global analysis of sub-daily Published: 29 June 2021 precipitation extremes. Publisher’s Note: MDPI stays neutral Keywords: sub-daily precipitation; sub-daily precipitation indices; PannEx RHP; Pannonian Basin with regard to jurisdictional claims in Experiment; climate of the carpathian region; INTENSE project published maps and institutional affil- iations. 1. Introduction Heavy rainfall and storm events constantly trigger important damages and significant Copyright: © 2021 by the authors. casualties in many regions, and enhanced understanding the variability of precipitation Licensee MDPI, Basel, Switzerland. This article is an open access article extremes would enable our communities to cope more efficiently with the challenges distributed under the terms and associated with the warming climate [1]. Understanding how and why precipitation conditions of the Creative Commons extremes vary is vital for disaster preparedness and to enable adequate water resource Attribution (CC BY) license (https:// management. This requires both understanding of how extremes have varied in the past creativecommons.org/licenses/by/ and the ability to provide estimates for how they might change under warming climate. 4.0/). One of the key statements of the IPCC Fifth Assessment Report centres around changes Atmosphere 2021, 12, 838. https://doi.org/10.3390/atmos12070838 https://www.mdpi.com/journal/atmosphere Atmosphere 2021, 12, 838 2 of 18 in the extremes of observed precipitation, e.g., ‘There are likely more land regions where the number of heavy precipitation events has increased than where it has decreased’ [2]. Analyses of the station data that have contributed to available global datasets display increasing trends in annual maximum daily precipitation [3]. The observed more frequent heavy precipitation events are also consistent with increasing amounts of water vapor in the atmosphere due to global warming [4]. In recent decades, an increasing number of studies have reported the presence of sig- nificant positive trends in precipitation extremes in Europe e.g., [5–9]. Significant trends in precipitation extremes over Europe have been observed since the middle of the 20th century in regional studies for Northern Europe [10], the UK [11], the Mediterranean region [12], and western and eastern parts of the Czech Republic [13] and Poland [14]. [15] showed that despite the considerable decadal variability, 5-, 10-, and 20-year events of 1-day and 5-day precipitation amounts for the first 20 years in the period 1951–2010 became more common in the analyzed 60 years for the daily precipitation series from the European Climate Assessment and Dataset (ECA&D, http://www.ecad.eu (accessed on 5 May 2021)) project [16,17]. The area in focus of this study is the Pannonian basin and its surroundings. The Pan- nonian/Carpathian basin (both names are used) is part of the larger Carpathian region. The precipitation climatology for the Carpathian region together with other climate variables are discussed either at seasonal or monthly scale [18,19] ( based on the CARPATCLIM dataset. The CARPATCLIM data covers the Carpathian Region and provide a homogenized [20,21], harmonized and gridded [22] dataset for climate studies. The precipitation amounts showed no significant trend, though it increased slightly on an annual basis in the period 1961–2010. The changes in the number of very wet days (daily precipitation > 20 mm) range between -2 and +3 days in extended regions. The highest increase appears in the Northeast Carpathians and the Bihor Mountains i.e., 7 days [23]. Considering the precipita- tion changes in Hungary, in the centre of the Carpathian region, a decrease of the annual precipitation sum is not remarkable (3%, 1901–2019). From the beginning of the 1990s, precipitation has been increasing both on annual and seasonal scales; however, this rise is not significant. Recent years have been dominated by the extremes. The magnitude of the change in precipitation intensity (mm/day) is about 1.3 mm/day in the countrywide average. The number of days with a daily sum above 20 mm increased by 1 day in the period 1901–2017 [24]. In Croatia, the observed changes in annual and seasonal precipi- tation amounts are also generally weak, particularly when trends from the beginning of 20th century were considered [25]. However, in the eastern mainland (Pannonia plain) a significant positive trend in the autumn season was detected from the second half of the last century [26]. It was associated with more very wet days and with an increase of their contribution to the total precipitation as well as an increase in maximal 1- and 5-day precipitation and in daily precipitation intensity. In general, the above-mentioned studies relied on daily or longer durations of pre- cipitation, whereas studies documenting the characteristics of sub-daily precipitation are fewer. However, such events are of great importance for society and economy since ex- treme sub-daily precipitation may be associated with hazardous events such as floods, soil erosion, and debris. Moreover, mountains can play an important role by blocking further movement of cloud systems or even enhancing precipitation-related processes leading to possible flash flood events [27]. Due to a higher number of impervious surfaces, urban areas have a higher risk of pluvial flooding. Hence, cities in the vicinity of mountains can be additionally endangered since their drainage systems need to handle additional water amounts. Fowler et al. [28] detected a notable minority of studies dealing with short-term rainfall, both on global or regional scales. Such studies are also sparse in the Pannonian region. Frequent occurrence, together with broad publicity for heavy rainfall events in recent years, has stimulated debates on the effects of climate change on the frequency and the magnitude of floods [29]. Due to spatial and temporal limitations of conventional climate models for Atmosphere 2021, 12, 838 3 of 18 resolving convective processes [30], measurements of short-term precipitation are of great importance for the analysis of such events. For Hungary, Lakatos et al. [31] analyzed the return values of the 60-min extreme rainfall events using the measurements of the automatic weather station network. The return period of extremely high values of short-term rainfall has shortened in recent years in Hungary, as it is shown in a case study for the Pécs-Pogány meteorological station [32]. In Croatia, the analyses of a short-term precipitation were made for a few selected locations, mainly in urban areas [27,33,34] and over the region of Istria [35]. Extremes of sub-daily precipitation have been studied in the Czech Republic by Beranova et al. 2018. They compared the characteristics of observed sub-daily precipitation extremes with those simulated by several regional climate models driven by reanalyses and examined diurnal cycles of hourly precipitation and their dependence on intensity and surface temperature.