Title Klimatološka analiza satnih indeksa oborinskih ekstrema Title (english) Climatological analysis of sub-daily indices of precipitation extremes Author Ana Starčević Mentor Ksenija Cindrić Kalin (mentor)Mentor Zoran Pasarić (komentor)Committee member Ksenija Cindrić Kalin (predsjednik povjerenstva)Committee member Zoran Pasarić (član povjerenstva)Committee member Ivana Herceg Bulić (član povjerenstva)Committee member Josip Stipčević (član povjerenstva)Committee member Zvjezdana Bencetić Klaić (član povjerenstva)Committee member Iva Dasović (član povjerenstva)Granter University of Zagreb Defense date and country 2024-02-12, Croatia Scientific / art field, NATURAL SCIENCES Abstract U ovom radu analizirani su intenziteti i učestalosti kratkotrajne jake oborine s pomoću indeksa ekstrema temeljenih na satnim vrijednostima oborine u trajanju od 1, 3 i 6 sati. Analiza je provedena prema satnim podacima ombrografskih postaja iz mreže DHMZ-a na cijelom području Hrvatske u razdoblju od 1961. do 2020., te uključuje osnovnu klimatologiju mjesečnih, sezonskih i godišnjih satnih maksimuma oborine. Rezultati pokazuju da se najviši intenziteti i učestalosti satnih oborinskih ekstrema u Hrvatskoj javljaju na sjevernom i južnom Jadranu te u Gorskom kotaru. Maksimalne vrijednosti indeksa intenziteta i učestalosti za svaku regiju zapažene su u isto doba godine, što sugerira zajednički uzrok povezan s vrhuncem konvektivne i grmljavinske aktivnosti. Na kontinentu su maksimalne satne oborine opažene tijekom ljeta, dok su u gorskim predjelima i duž Jadrana primijećene nešto kasnije, krajem ljeta i početkom jeseni. Također, uočeni su značajni udjeli satnih ekstrema u dnevnoj oborini na kontinentu, što upućuje na to da ove pojave mogu biti rezultat izoliranih događaja kratkog trajanja ili dijelom dužih oluja s izraženim vrhuncem. Analiza pokazuje da se satni maksimumi oborine najčešće pojavljuju oko ponoći, dok se tijekom toplijeg dijela godine zapažaju i u popodnevnim satima na kontinentu te u noćnim satima na jadranskoj obali i otocima. Preliminarna analiza trendova godišnjih maksimuma satne oborine uputila je na nedostatak dugih i potpunih nizova ombrografskih mjerenja, onemogućujući izračun trenda za sve postaje tijekom cijelog analiziranog razdoblja. Većina postaja pokazuje trend intenzifikacije kratkotrajne jake oborine u razdoblju od 1981. do 2020., statistički značajan samo na nekoliko postaja. Dodatno su uspoređeni srednjaci indeksa intenziteta i trajanja u dva klimatološka razdoblja, te je u posljednjem 30-godišnjem razdoblju primijećen porast u broju kišnih sati, intenzitetu satne oborine i prosječnom trajanju kišnih epizoda. Ovaj rad predstavlja prvu klimatološku analizu
kratkotrajne oborine u Hrvatskoj, a rezultati mogu poslužiti kao korisna podloga za procjenu rizika od bujičnih poplava, kao i za klimatsko modeliranje i prilagodbu na klimatske promjene. Također, rezultati mogu biti osnova za izradu kriterija upozorenja na jake kiše, koji bi se zbog klimatskih promjena trebali redovito pratiti i revidirati.
Abstract (english) In this study, we analyzed the intensities and frequencies of short-term heavy rainfall using extreme indices based on sub-daily rainfall values with durations of 1, 3, and 6 hours. The analysis was conducted using hourly data from rain gauges in the DHMZ network across Croatia for the period from 1961 to 2020. It includes basic climatology of monthly, seasonal, and annual sub-daily rainfall maxima. The results indicate that the highest intensities and frequencies of sub-daily rainfall extremes in Croatia occur in the northern and southern Adriatic regions and Gorski kotar. The timing of peak intensity and frequency of extreme events both occur in the same season for each region, suggesting that these aspects are influenced by similar processes linked to the peak of convective and thunderstorm activity. On the mainland, maximum sub-daily rainfall is observed during the summer, while in mountainous areas and along the Adriatic coast, it is noticed somewhat later, towards the end of summer and the beginning of autumn. Significant contributions to daily rainfall from sub-daily extremes were also observed on the mainland, indicating that these events may result from either isolated short-duration events or are part of longer storms with pronounced peaks. The analysis reveals that the timing of the wettest hour predominantly occurs around midnight. However, in the warmer months, the timing of the wettest hour is also observed in the afternoon on the mainland and during the night on the Adriatic coast and islands. Preliminary analysis of trends in annual maximum sub-daily precipitation highlights a limitation arising from the insufficient availability of long and complete ombrographic measurement series. This limitation hinders trend calculation for all stations over the entire analyzed period. The majority of stations exhibit a trend of increased short-term heavy precipitation amounts from 1981 to 2020, with statistical significance observed only at a few stations. Comparing the means of intensity and duration indices in two climatological periods indicates an increase in the number of wet hours, sub-daily precipitation intensity, and average duration of wet spells, particularly in the latter 30-year period. This study represents the first climatological analysis of short-term precipitation in Croatia. The findings offer a valuable foundation for evaluating the risk of flash floods, as well as for climate modeling and adapting to climate change. Additionally, the results can form the basis for developing criteria for heavy rainfall warnings, which should be regularly monitored and revised due to climate changes.
Keywords
kratkotrajne jake oborine
indeksi ekstrema
klimatske promjene
trend
Keywords (english)
sub-daily extreme rainfall
extreme indices
climate change
trend
Language croatian URN:NBN urn:nbn:hr:217:076154 Study programme Title: graduate academic research programme: Master of Physics – geophysics, modules: Seismology and solid Earth physics, Meteorology and physical oceanography; specializations in: Seismology and solid Earth physics, Meteorology and physical oceanography Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2024-03-01 12:02:37
