Spatial variability of seasonal precipitation in Slovenia in the period 2010–2019

Prostorsko variabilnost količine padavin v Sloveniji smo ovrednotili z analizo razdalje razgradnje korelacije CDD (angl. Correlation Decay Distance), ki prikazuje spremembo korelacije v količini padavin med meteorološkimi postajami glede na njihovo medsebojno oddaljenost. Uporabili smo podatke tistih meteoroloških postaj (n = 160), ki so na isti lokaciji neprekinjeno beležile količino padavin vseh 120 mesecev (december 2009–november 2019). Za vsako meteorološko postajo smo po posameznih letnih časih izračunali mejno razdaljo, pri kateri je korelacija med količino padavin višja od 0,707 (r2 = 0,5). Rezultati kažejo, da se prostorska variabilnost količine padavin med letnimi časi razlikuje, in sicer je najvišja poleti (CDD = 50 km), sledi pomlad (CDD = 76 km) in jesen (CDD = 120 km) ter zima (CDD = 141 km), ko je prostorska variabilnost količine padavin najnižja. Prostorsko gledano je variabilnost količine padavin podobna spomladi in jeseni (najmanjša prostorska variabilnost padavin v V in JV Sloveniji), medtem ko je poleti najnižja v J Sloveniji, pozimi pa v SZ Sloveniji. Karta variogramov prikazuje anizotropijo v razdalji razgradnje korelacije za spomladanske padavine. Višje vrednosti semivariance so očitne v smeri SV-JZ, medtem ko so vrednosti semivariance v smeri JV-SZ precej nižje.The spatial variability of precipitation in Slovenia was evaluated using correlation decay distance analysis (CDD). CDD analysis essentially explores how the correlation between neighbouring stations varies according to distance. We analysed CDD for the period December 2009–November 2019 using only those meteorological stations (n = 160) with no missing values and operating at same location for the whole analysed period. For each meteorological station, we calculated the threshold distance at which the correlation between series is higher than 0.707 (r2 = 0.5). The results indicate that the highest spatial variability in precipitation is during summer (CDD = 50 km), followed by spring (CDD = 76 km), autumn (CDD = 120 km) and winter (CDD = 141 km), when the spatial variability is the lowest. The spatial variability of precipitation is similar in spring and autumn (with the lowest variability of precipitation in E and SE Slovenia), and it is lowest in S Slovenia in summer and in NW Slovenia in winter. The variogram map indicates anisotropy in the correlation decay distance for spring precipitation. Higher values of semivariance are evident in the NE-SW direction, while semivariance values in the SE-NW direction are much lower