© 2016 Dragan D. Milošević et al., published by De Gruyter Open.This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.

Open Geosci. 2016; 8:593–605

Research Article Open Access

Dragan D. Milošević*, Stevan M. Savić, Milana Pantelić, Uglješa Stankov, Igor Žiberna,Dragan Dolinaj, and Igor Leščešen

Variability of seasonal and annual precipitation inSlovenia and its correlation with large-scaleatmospheric circulationDOI 10.1515/geo-2016-0041Received April 3, 2015; accepted December 17, 2015

Abstract: This paper examines temporal and spatial vari-ability and trends of annual and seasonal precipitation inSlovenia and their relationshipwith three atmospheric cir-culation patterns represented by their indices: North At-lantic Oscillation index (NAOi), Mediterranean Oscillationindex (MOi) andWestern Mediterranean Oscillation index(WeMOi). Data from 45 precipitation stations were usedfor the period 1963–2012.Mean annual precipitation variesfrom 736 mm in eastern Slovenia to 2,518 mm in north-western Slovenia. A significant annual precipitation de-crease (from −3% to −6% per decade) is observed in west-ern Slovenia. Significant negative trends are observed insouthwestern Slovenia in summer (from −4% to −10%perdecade) and near the Adriatic coast in spring (from −6% to−10% per decade). Non-significant negative and positivetrends are observed in winter and autumn, respectively.Results indicate significant correlations between winterprecipitation and MOi (from −0.3 to −0.7), NAOi (from−0.3 to −0.6) andWeMOi (from 0.3 to 0.6). Significant We-MOi influence is observed in spring and autumn, whileNAOi and MOi influence has not been detected. Annualprecipitation and WeMOi are significantly correlated incentral and eastern Slovenia, while significant NAOi andMOi influence is observed in western Slovenia (with thelarger area covered by MOi influence).

Keywords: precipitation; atmospheric circulation; NorthAtlantic Oscillation; Mediterranean Oscillation; WesternMediterranean Oscillation; Slovenia

*Corresponding Author: Dragan D. Milošević: Climatology andHydrology Research Centre, Faculty of Science, University of NoviSad; Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia, E-mail:dragan.milosevic@dgt.uns.ac.rsStevan M. Savić, Milana Pantelić, Dragan Dolinaj: Climatologyand Hydrology Research Centre, Faculty of Science, University ofNovi Sad; Trg Dositeja Obradovića 3, 21000 Novi Sad, Serbia

1 IntroductionPrecipitation is a very important meteorological elementin the Mediterranean region (MR) as its future change canimpact human activities (e.g. water management, agricul-ture) and ecosystems. Significant progress has been madeon climate projections for theMR [1]. Future projections re-garding seasonal precipitation show predominant reduc-tions for spring, summer and autumn, however projec-tions for winter are distinctly different [2]. Precipitation isprojected to decrease in all parts and all seasons (themostsignificant percent change occurs in summer) except forthe northernmost parts in winter [3]. This is in accordancewith the expected drying over the MR as a part of globalwarming [4].

Precipitation variability and trends in the MR havebeen analyzed in many studies. For example, Ziv et al. [5]analyzed changes in the precipitation regime of Israelshowing a statistically non-significant decreasing trendprevailing in most of the country. The majority of Is-rael has significant precipitation decrease only duringspring. Luković et al. [6] examined spatial patterns of rain-fall trends in Serbia suggesting only weak, mostly non-significant trends. The study of de Luis et al. [7] has showna significant annual precipitation decrease in northwest-ern and western Slovenia and during all seasons, exceptautumn.

As local changes in meteorological variables in mid-latitudes are mainly controlled by atmospheric circula-tion [8, 9], the correlations between circulation indices

Uglješa Stankov: Center for Spatial Information of VojvodinaProvince, Faculty of Science, University of Novi Sad, Trg DositejaObradovia 3, 21000 Novi Sad, SerbiaIgor Žiberna: Department of Geography, Faculty of Arts, Universityof Maribor, Koroška cesta 160, Maribor, SloveniaIgor Leščešen: Department of Geography, Tourism and Hotel Man-agement, Faculty of Science, University of Novi Sad; Trg DositejaObradovića 3, 21000 Novi Sad, Serbia

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594 | Dragan D. Milošević et al.

and precipitation in the MR are very important to analyze.The relationships between atmospheric circulation pat-tern indices and precipitation in Slovenia have not beenwell identified: only a few studies [10, 11] have been madeon this topic with only a limited number of precipitationstations investigated.Oneof the goals in this paper is to an-alyze these relationships in order to obtain a better under-standing of the causes of precipitation variability in Slove-nia. The study includes data on the large-scale North At-lantic Oscillation (NAO) and regional Mediterranean andWestern Mediterranean Oscillations (MO and WeMO, re-spectively) known to affect the MR.

NAO is associated with a meridional dipole structurein sea level pressure with two centers of action locatednear Iceland and the Azores [12]. A positive NAO phaseleads to more intense precipitation over northern Europe,whereas a negative NAO phase causes a precipitation shifttowards southern Europe [8]. The influence of NAO on pre-cipitation in the MR has been investigated by a number ofauthors [5, 8, 10–14]. A study by Sušelj and Bergant [11]showed significant negative correlation betweenNAOi andprecipitation in Slovenia. However, this interpretation islimited by the fact that only four selected meteorologicalstations represented the whole country which is geomor-phologically and climatologically diverse.

MO was defined in order to explain opposing atmo-spheric dynamics between the western and eastern partof the Mediterranean basin. The original MOi was definedas normalized pressure difference between Algiers andCairo [15]. A second version of this index, which was usedin this paper, can be calculated as the difference of stan-dardized pressure anomalies at Gibraltar and the Israelimeteorological station of Lod [16]. The influence of MOon precipitation variability has been analyzed in numer-ous studies [5, 10, 11, 13, 17–19]. A study of Sušelj andBergant [11] showed significant negative correlation be-tween MOi and precipitation in Slovenia as registered atfour selected meteorological stations (Ljubljana, MurskaSobota, Rateče and Postojna).

WeMO was defined by Martin-Vide and Lopez-Bustins [20] by means of the dipole composed by an an-ticyclone over the Azores and a depression over Liguria.This is the situation with a WeMO positive phase, whilein the negative phase the situation is the opposite. We-MOi was defined as the result of the difference betweenstandardized values in surface atmospheric pressure inSan Fernando (Spain) and Padua (Italy). WeMOi’s influ-ence on climate variability in the Iberian Peninsula hasbeen analyzed by Martin-Vide and Lopez-Bustins [20] andMartin-Vide et al. [21].

The Republic of Slovenia is situated in the central-southern part of Europe (Figure 1) abutting four distinctgeographical regions: theMediterraneanSea, theAlps, theDinaric Alps and the Pannonian Basin [22]. Slovenia ex-tends between 45°25’ and 46°30’ N and 13°23’ and 16°36’E [23] and covers an area of 20,273 km2 [22] with a pop-ulation of 2.06 million. The Alpine macroregion is in thenorth of Slovenia, while the Mediterranean macroregionis in the west of Slovenia. Toward the east, the Mediter-ranean macroregion is replaced by the Dinaric macrore-gion that stretches in a northwest-southeast direction andcovers most of the southern part of Slovenia. The Pannon-ian macroregion is a densely populated and intensivelycultivated area at the east end of Slovenia [24] (Figure 1).Submediterranean, temperate continental and alpine cli-matic influences intertwine in the territory of Slovenia.However, most of Slovenia has a temperate continentalclimate. Alpine climate characterizes higher and lowermountain areas to the north andwest of the country, whilea submediterranean climate is present in the south andsouthwest of the country at the Adriatic coast (coastal sub-mediterranean climate) and its hinterland (inland sub-mediterranean climate). Continental climate intensifieswith the distance increase from the Adriatic Sea and Alps-Dinaric mountain barrier towards the eastern and north-eastern Slovenia [25].

In the study of de Luis et al. [7] it was discussed thatchanges in large-scale atmospheric circulation patternsmay have contributed to an observed long-term drying inSlovenia. This study contributes to the investigation ofthese suggested relationships. The main goals of this pa-per are to investigate temporal and spatial variability andtrends of annual and seasonal precipitation in Sloveniaand to correlate themwith indices of the large-scale (NAOi)and regional (MOi and WeMOi) atmospheric circulationpatterns, which are more representative for MR precipita-tion.

2 Data and methodsAnnual and seasonal precipitation in Slovenia recorded at45 stations was analyzed (Figure 1, Table 1). Selected pre-cipitation stations are locatedon the territory of eachof thedifferent geographical regions of Slovenia: 16 in theAlpinemacroregion, 15 in the Dinaric macroregion, 10 in the Pan-nonian macroregion and 4 in the Mediterranean macrore-gion. Selection of adequate stations was based on the dataavailability and homogeneity as well as macroregions’ av-erage size and altitudes.

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Variability of seasonal and annual precipitation in Slovenia | 595

Table 1: List of stations included in this study.

Station Latitude Longitude Altitude (m)Bilje (BLJ) 45°54’ 13°38’ 55Brege (BG) 45°55’ 15°30’ 150

Dobliče (Črnomelj) (DO) 45°34’ 15°09’ 157Morsko (MK) 46°05’ 13°38’ 170Bizeljsko (BZ) 46°01’ 15°42’ 179

Murska Sobota (MS) 46°39’ 16°11’ 188Lendava (LD) 46°34’ 16°28’ 195Dvor (DV) 45°48’ 14°48’ 203

Novo Mesto (NM) 45°48’ 15°11’ 220Laško (LS) 46°09’ 15°14’ 223Ptuj (PT) 46°26’ 15°54’ 235Celje (CLJ) 46°15’ 15°15’ 240

Mokronog (MO) 45°57’ 15°09’ 251Fužina (FZ) 45°52’ 14°50’ 264

Maribor-Sabor (MB) 46°32’ 15°39’ 275Ljubljana-Bežigrad (LJB) 46°04’ 14°31’ 299

Veliki Dolenci (VD) 46°50’ 16°17’ 308Kadrenci (KC) 46°34’ 15°57’ 316Godnje (GD) 45°45’ 13°51’ 320

Slovenske Konjice (SK) 46°20’ 15°26’ 332Škofja Loka (SL) 46°10’ 14°18’ 340

Poljane (Škofja Loka) (PLJ) 46°07’ 14°11’ 385Kranj (KA) 46°14’ 14°22’ 395

Gornji Grad (GG) 46°18’ 14°50’ 428Kotlje (KT) 46°31’ 14°59’ 450

Bukovščica (BU) 46°14’ 14°16’ 458Kočevje (KO) 45°39’ 14°51’ 467Kozina (KZ) 45°36’ 13°56’ 490Postojna (PO) 45°46’ 14°12’ 533Podgrad (PR) 45°32’ 14°09’ 560Sodražica (SO) 45°46’ 14°39’ 560Cerknica (CK) 45°48’ 14°22’ 576Mislinja (MI) 46°27’ 15°13’ 589Šmarata (SM) 45°41’ 14°29’ 590

Črni Vrh (Idrijp) (CV) 45°56’ 14°03’ 683Jurišče (JU) 45°40’ 14°18’ 703Rut (RU) 46°12’ 13°54’ 710

Zgornja Radovna (ZR) 46°25’ 13°56’ 750Jelendol (JD) 46°24’ 14°21’ 760

Kranjska Gora (KG) 46°29’ 13°48’ 804Hrib (HB) 45°42’ 14°36’ 825

Rateče-Planica (RT) 46°30’ 13°43’ 864Javorniški Rovt (JR) 46°28’ 14°06’ 940

Lokve (LO) 46°01’ 13°47’ 965Planina pod Golico (PG) 46°28’ 14°03’ 970

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596 | Dragan D. Milošević et al.

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Station

Sources: Esri, DeLorme, NAVTEQ,TomTom, Intermap, increment P Corp.,GEBCO, USGS, FAO, NPS, NRCAN,GeoBase, IGN, Kadaster NL, OrdnanceSurvey, Esri Japan, METI, Esri China(Hong Kong), swisstopo, and the GIS0 10050 km

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Figure 1: Geographical location of the Republic of Slovenia in Eu-rope and the precipitation stations in the Republic of Slovenia.

The investigated period is from 1963 to 2012. Precip-itation amounts were obtained from the EnvironmentalAgency of the Republic of Slovenia (EARS). Winter (DJF),spring (MAM), summer (JJA) and autumn (SON) precip-itation were calculated for each station using the stan-dard seasons definition. Winter precipitation correspondsto January-February of the calendar year and to Decemberof the previous year, while precipitation for other seasonscorresponds to the months from the calendar year.

A standard Normal Homogeneity Test (SNHT) was ap-plied for the detection of abrupt homogeneity breaks [26]inmonthly precipitation values. The test is based upon theassumption that the difference between precipitation se-ries at a candidate station (the one being tested) and thereference series is fairly constant in time. Reference se-ries were chosen from 4 to 6 stations, based on distance,similar altitude and squared correlation coefficient from0.3 to 0.8 with the test station. The critical level of thistest was 95% [27]. Inhomogenieties were detected and cor-rected [28].

Simple linear regression was used for obtaining an-nual and seasonal precipitation trends, while a Mann-Kendall nonparametric statistical test [29] was used todemonstrate the statistical significance of trends [30].Statistical significance was defined at the level of 95%and 99%. Rates of precipitation changes are expressedas %/decade, due to the differences in total precipitationamounts between regions [7].

In order to understand Slovenian precipitation and itsrelationship with atmospheric circulation patterns better,indices were examined using correlation analysis. Pear-son’s correlation was used to reflect the degree of lin-ear relationship between the precipitation and the atmo-spheric circulation pattern indices (NAOi, MOi and We-

MOi). Monthly NAOi values were obtained from the Na-tional Oceanic and Atmospheric Association (NOAA) Cli-mate Prediction Center (CPC) website [31]. Daily valuesof MOi were obtained from Climatic Research Unit web-site [32]. MonthlyWeMOi data were obtained from the Uni-versity of Barcelona website [33]. Annual and seasonalNAOi and WeMOi were calculated using monthly series,while annual and seasonal MOi were calculated usingdaily series.

The spatial distribution of the results is displayed us-ing spatial interpolation (an ordinary Kriging method) ofthe observed precipitation and precipitation trends for the45 stations using the geostatistical software package AR-CGIS 10.1 with the Geostatistical Analyst Extension.

3 Results

3.1 Results of homogenisation

During the homogeneity testing of precipitation, the de-tected break points were compared to metadata recordsin order to diagnose the causes of any observed inhomo-geneity [34]. This type of informationwas crucial for apply-ing calculated corrections to the investigated series [35].In most cases, the break points were related to the relo-cation of a station. From 45 stations used in the paper,23 were relocated during the investigated period. For in-stance, most breaks happened at the station Kozina (KZ)(26 breaks) which was relocated four times during the re-search period. In other cases, breaks were related to miss-ing values. 22 stations hadmissing values, but they did notexceed 5%of each station dataset. After a series of individ-ual or multiple homogeneity adjustments [36] conductedwithin this study, the series were considered to be homo-geneous. The adjustment values of themonthly time seriesusually ranged from −5 to 5 mm.

3.2 Precipitation and precipitation regimes

The highest annual precipitation amounts (>2400 mm)were registered at stations located in the northwestern,mountainous part of Slovenia, influenced by interactionbetween alpine and submediteranean airmasses. Towardsthe east, continental climate influence prevails with thelowest precipitation amounts recorded in the northeast-ern, Pannonian part of the country (<800mm) (Figure 2a).

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Variability of seasonal and annual precipitation in Slovenia | 597

Figure 2: Spatial distribution of mean precipitation amounts (mm) (a - annual; b - winter; c - spring; d - summer; e - autumn) in Sloveniaduring the 1963-2012 period.

During winter, the highest precipitation amounts areregistered at stations located in the northwestern, moun-tainous part of Slovenia (550–650 mm) influenced byalpine climate. Southwestern Slovenia is influenced bysubmediterranean climate and receives between 250 and350 mm. The largest part of the country receives less than

250 mm and is influenced by temperate continental cli-mate (Figure 2b).

In spring, western mountainous Slovenia is still thewettest part of the country (550–650mm),while the largestpart of the country receives more precipitation (250–350mm) compared towinter. Northeastern Slovenia, influ-

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598 | Dragan D. Milošević et al.

enced by continental climate, receives less than 250 mm(Figure 2c).

Summer is characterized by a significant increase ofprecipitation in the eastern part of the country, influencedby continental climate, and reaching its seasonal precip-itation maximum (250–300 mm). The largest part of thecountry receives between 350 and 450 mm, while north-western Slovenia receives between 450 and 550 mm (Fig-ure 2d).

In autumn, the seasonal precipitationmaximum is ev-ident in the area of alpine (northwestern Slovenia) andsubmediterranean climate (southwestern Slovenia) with>750 mm and from 450 mm to 550 mm, respectively (Fig-ure 2e).

3.3 Precipitation trends

A non-significant annual precipitation decrease was reg-istered throughout Slovenia. However, statistically signif-icant negative trends (from −3% to −6% per decade, i.e.from −28 mm per decade to −127 mm per decade) wereregistered at 13 stations out of 45, mainly located in south-western and northwestern Slovenia (Figure 3a).

During winter, non-significant negative trends werenoted over the majority of the country (36 out of 45 sta-tions). The largest decrease was noted in northeastern(from −4% to −7% per decade) as well as northwesternSlovenia and near the Adriatic Sea (from −4% to −6% perdecade). Only one small part of southern Slovenia is char-acterized by non-significant positive trends (Figure 3b).

Spring precipitation decrease was noted in the wholecountry. Non-significant negative trends are registered incentral (from −4%to −6%per decade), western and north-eastern Slovenia (from −6% to −8%per decade). However,a statistically significant decrease was registered at onlythree stations near the Adriatic coast (from −6% to −10%per decade, i.e. from −24 mm per decade to −49 mm perdecade) (Figure 3c).

A decrease in summer precipitation was noted over amajority of the country (44 out of 45 stations). A statisti-cally significant precipitation decrease was observed at 13out of 45 stations mainly in southwestern Slovenia (from−4% to −10% per decade, i.e. from −20 mm per decadeto −46 mm per decade), where influences of submediter-ranean and continental climate intertwine (Figure 3d).

Autumn in Slovenia was characterized by a non-significant precipitation increase over the majority of thecountry (35 out of 45 stations), with negative trends (from−2% to −4% per decade) noted only in the west of the

country. The largest increase was observed in centralSlovenia (from 2% to 4% per decade) (Figure 3e).

3.4 The correlations between atmosphericcirculation patterns and precipitation

In general, correlations between MOi, NAOi and precipi-tation in Slovenia are negative, while WeMOi and precip-itation have positive correlations on annual and seasonalscales (Table 2). This suggests that precipitation in Slove-nia is decreasing during positive NAO and MO phases,while the positive phase of WeMO results in more precipi-tation in Slovenia.

Annual precipitation in Slovenia was significantly in-fluenced byWeMOi at 21 out of 45 stations (significant cor-relations from 0.3 to 0.6), MOi at 17 out of 45 stations (sig-nificant correlations from −0.3 to −0.4) and NAOi at 10 outof 45 stations (significant correlations from −0.3 to −0.4)(Table 2). The spatial patternof these relationships showedthat WeMOi influence is dominant in central and easternSlovenia, while MOi and NAOi influence is dominant inwestern Slovenia with the larger area under the MOi influ-ence (Figure 4).

The strongest correlations between NAOi, MOi andseasonal precipitation in Slovenia are noticed in winter.Significant negative correlations (from −0.3 to −0.7) be-tween MOi and precipitation are present in the majority ofthe country (43 out of 45 stations) (Table 2). Only stationslocated in southeastern Slovenia are not significantly in-fluenced by this atmospheric circulation pattern. Similarresults are obtained between NAOi and precipitation, butwith smaller correlation values (from −0.3 to −0.6) andwith a smaller covered area (32 out of 45 stations) (Table 2).Eastern Slovenia is not covered by significant NAOi influ-ence. Significant WeMOi influence is noticed at 31 out of45 stations with correlation values ranging from 0.3 to 0.6(Table 2). Central, southeastern Slovenia and the area nearthe Adriatic Sea are not significantly influenced by this cir-culation (Figure 4).

Only WeMOi significantly influences spring precipita-tion in the larger part of Slovenia. Compared to this, cor-relations between MOi, NAOi and precipitation are rathersmall and non-significant. WeMOi is positively correlated(from 0.3 to 0.5) with precipitation throughout the country(40 out of 45 stations) (Table 2), except for small area in thenorth and northeast (Figure 4).

During summer, the precipitation distribution in themajority of the country is not significantly influenced bythe investigated atmospheric circulation patterns. It mightbe that local factors (i.e. orography) shield certain re-

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Figure 3: Spatial distribution of long-term trends (%/decade) of precipitation amounts (a - annual; b - winter; c - spring; d - summer; e -autumn) in Slovenia during the 1963-2012 period. Values significant at the 95% and 99% level (two-tailed). NS - non-significant.

gions from the variability represented by the atmosphericmodes. As noticed in previous research, at fine geograph-ical scales the effects of atmospheric circulation are mod-ified by topography, particularly in areas of complex ter-rain [37, 38]. Significant influence (from −0.3 to −0.4) ofMOi is noticed in eastern Slovenia and WeMOi in north-western Slovenia (from 0.3 to 0.4) (Table 2). SignificantNAOi influence (−0.3) (Table 2) is registered at only two

stations, located in the northwestern part of the country(Figure 4).

Non-significant correlationswere found betweenMOi,NAOi and autumn precipitation in Slovenia. Compared tothis, WeMOi is significantly correlated (from 0.3 to 0.5)with precipitation in themajority of the country, except forsmall areas in central and northern Slovenia (Table 2) (Fig-ure 4).

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Table 2: Correlation coeflcients between annual and seasonal precipitation and atmospheric circulation pattern indices in Slovenia duringthe 1963-2012 period. Values significant at the 95% (italic) and 99% level (bold) (two-tailed).

StationWinter Spring Summer Autumn Annual

NAO MO WeMO NAO MO WeMO NAO MO WeMO NAO MO WeMO NAO MO WeMOBG −0.2 −0.3 0.5 0.0 0.0 0.4 0.3 −0.2 0.0 −0.2 −0.1 0.4 0.0 −0.1 0.2BLJ −0.5 −0.7 0.2 −0.2 −0.2 0.4 0.0 −0.1 0.4 −0.3 −0.2 0.3 −0.3 −0.3 0.3BU −0.5 −0.6 0.3 −0.2 0.0 0.5 −0.1 −0.1 0.1 −0.1 −0.1 0.3 −0.2 −0.2 0.3BZ −0.1 −0.2 0.6 −0.1 0.1 0.5 0.2 −0.2 0.0 −0.2 0.0 0.4 0.0 0.0 0.3CK −0.4 −0.5 0.4 −0.1 −0.1 0.4 0.0 −0.1 0.3 −0.1 −0.1 0.4 −0.1 −0.2 0.4CLJ −0.3 −0.4 0.5 0.0 0.1 0.4 0.1 −0.3 −0.1 −0.2 0.0 0.3 −0.1 −0.1 0.2CV −0.5 −0.6 0.3 −0.3 0.0 0.5 −0.1 −0.1 0.3 −0.2 −0.1 0.3 −0.3 −0.4 0.3DO −0.4 −0.4 0.4 0.0 0.1 0.3 0.1 −0.3 −0.1 −0.1 −0.1 0.4 −0.1 −0.2 0.2DV −0.3 −0.4 0.4 0.0 0.0 −0.1 0.1 −0.2 0.2 −0.1 −0.1 0.2 −0.1 −0.1 0.2FZ −0.4 −0.4 0.4 −0.1 0.0 0.2 0.0 −0.2 −0.1 −0.2 −0.1 0.3 −0.3 −0.3 0.1GD −0.5 −0.6 0.2 −0.2 −0.1 0.4 −0.2 0.0 0.2 −0.1 −0.1 0.4 −0.3 −0.4 0.3GG −0.3 −0.5 0.3 0.0 0.1 0.4 0.0 −0.1 0.1 −0.3 −0.1 0.3 −0.1 −0.2 0.2HB −0.5 −0.5 0.4 −0.1 0.0 0.4 0.0 −0.2 0.1 −0.2 −0.1 0.4 −0.3 −0.2 0.4JD −0.5 −0.6 0.3 −0.1 0.0 0.5 0.0 −0.1 0.2 −0.1 −0.1 0.3 −0.1 −0.2 0.5JR −0.4 −0.6 0.2 −0.1 −0.1 0.4 −0.1 −0.1 0.1 −0.1 −0.1 0.3 −0.2 −0.4 0.2JU −0.5 −0.5 0.3 −0.2 0.0 0.4 −0.1 −0.2 0.2 −0.1 −0.1 0.4 −0.1 −0.3 0.5KA −0.6 −0.7 0.2 −0.1 0.0 0.1 0.0 −0.1 0.1 −0.2 −0.1 0.0 −0.3 −0.4 0.2KC −0.2 −0.4 0.4 0.1 0.0 0.3 0.1 −0.3 0.1 −0.2 0.0 0.4 −0.1 −0.2 0.2KG −0.5 −0.6 0.3 −0.1 0.0 0.5 −0.3 0.1 0.2 −0.2 −0.1 0.3 −0.3 −0.3 0.3KO −0.4 −0.4 0.4 0.0 0.0 0.4 0.0 −0.3 0.0 −0.2 0.0 0.4 −0.3 −0.1 0.4KT −0.2 −0.4 0.4 0.2 0.0 0.4 0.0 −0.2 −0.1 −0.1 −0.1 0.3 0.0 −0.2 0.1KZ −0.5 −0.6 0.3 −0.3 −0.1 0.3 0.0 −0.1 0.2 −0.1 0.0 0.5 −0.2 −0.3 0.5LD −0.3 −0.4 0.4 0.1 0.1 0.3 0.0 −0.4 0.1 −0.1 0.0 0.4 −0.1 −0.3 0.2LJB −0.5 −0.5 0.4 −0.1 0.0 0.4 0.0 −0.1 −0.1 −0.3 −0.1 0.3 −0.2 −0.3 0.3LO −0.5 −0.6 0.2 −0.2 −0.1 0.4 −0.2 −0.1 0.3 −0.2 −0.2 0.4 −0.4 −0.4 0.3LS −0.3 −0.4 0.4 0.0 0.0 0.4 0.2 −0.3 −0.1 −0.2 −0.1 0.3 0.1 −0.2 0.1MB −0.2 −0.3 0.4 0.1 0.0 0.4 0.1 −0.3 0.1 −0.2 0.1 0.5 0.2 −0.1 0.3MI −0.2 −0.4 0.4 0.0 0.1 0.4 0.0 −0.2 0.0 −0.2 0.0 0.3 0.0 −0.2 0.1MK −0.5 −0.6 0.2 −0.2 0.0 0.5 −0.2 −0.1 0.4 −0.1 −0.1 0.3 −0.3 −0.3 0.4MO −0.3 −0.4 0.4 −0.1 0.1 0.3 0.0 −0.2 −0.1 −0.1 −0.1 0.4 −0.2 −0.2 0.2MS −0.2 −0.4 0.4 0.1 0.1 0.3 0.0 −0.3 0.0 −0.2 0.1 0.4 0.0 −0.2 0.1NM −0.2 −0.3 0.4 0.0 0.0 0.3 0.2 −0.2 −0.2 −0.1 −0.1 0.3 0.1 −0.1 0.2PD −0.5 −0.6 0.3 −0.1 0.0 0.4 −0.1 −0.1 0.2 −0.1 −0.2 0.3 −0.1 −0.4 0.2PG −0.5 −0.6 0.2 −0.1 −0.1 0.4 −0.2 −0.2 0.0 −0.1 −0.1 0.3 −0.3 −0.4 0.2PI −0.5 −0.6 0.3 −0.3 −0.1 0.4 0.0 −0.3 0.1 −0.1 −0.1 0.4 −0.3 −0.4 0.4PO −0.5 −0.5 0.3 −0.1 0.0 0.4 0.0 0.0 0.4 −0.1 −0.1 0.4 −0.1 −0.3 0.6PT −0.2 −0.4 0.4 0.0 0.0 0.4 0.2 −0.4 0.1 −0.2 0.1 0.4 0.0 −0.2 0.3RT −0.5 −0.6 0.3 −0.2 0.0 0.5 −0.3 0.1 0.2 −0.2 −0.1 0.3 −0.3 −0.2 0.3RU −0.4 −0.5 0.3 −0.2 0.0 0.5 −0.2 −0.1 0.3 −0.2 −0.2 0.3 −0.3 −0.4 0.3SK −0.3 −0.4 0.5 0.1 0.0 0.4 0.1 −0.3 0.1 −0.2 0.0 0.3 0.0 −0.1 0.2SL −0.5 −0.6 0.3 −0.2 0.0 0.5 −0.1 −0.1 0.2 −0.1 −0.1 0.3 −0.2 −0.3 0.3SM −0.4 −0.5 0.4 −0.1 −0.1 0.3 0.0 −0.2 0.1 −0.2 −0.1 0.4 −0.3 −0.4 0.3SO −0.4 −0.4 0.4 −0.1 0.0 0.3 0.1 −0.2 0.1 −0.1 −0.1 0.4 −0.3 −0.2 0.4VD −0.3 −0.4 0.4 0.1 0.0 0.4 0.0 −0.3 −0.1 −0.1 0.1 0.4 0.0 −0.1 0.1ZR −0.4 −0.6 0.2 −0.1 −0.1 0.4 −0.2 −0.1 0.1 −0.2 −0.1 0.3 −0.3 −0.4 0.2

4 Discussion and conclusionsThe statistical analysis of annual and seasonal data from anetwork of precipitation stations in Slovenia from 1963 to2012 has allowed for quantitatively characterizing precip-itation variability in the study area and for assessing sim-

ilarities and differences with respect to precipitation fluc-tuations in other areas of the MR.

The highest precipitation amounts are registered atthe mountains in western Slovenia with a decrease to-wards the northeast of the country. This is due to the factthat western Slovenia is exposed to the inflow of moisture

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Figure 4: Correlations between annual and seasonal (winter; spring; summer; autumn) precipitation and atmospheric circulation patternindices in Slovenia during the 1963-2012 period. Values significant at the 95% and 99% level (two-tailed). NS - non-significant.

from the Adriatic Sea and to topographically-induced pre-cipitation by the Alps and the Dinaric Alps.

Negative annual and seasonal (except autumn) pre-cipitation trends are observed. A significant precipitation

decrease was noticed in spring (from −6% to −10% perdecade) and summer (from −4% to −10%per decade) andat an annual timescale (from −3% to −6% per decade) insouthwestern and western Slovenia. Non-significant de-

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602 | Dragan D. Milošević et al.

creasing trends (up to −7%per decade) during winter andnon-significant increasing trends during autumn (up to4%per decade)were registered in themajority of the coun-try. Compared to the study of de Luis et al. [7] that analyzedprecipitation in Slovenia for the 1950-2007 period, thisstudy obtained higher negative trends during spring andsummer and smaller during winter, while annual trendshad the same values. Annual and seasonal trends fromourstudy agreewith trends derived fromE-OBS gridded obser-vations [39]. ERA-Interim meteorological reanalysis [40]and results from our study showed increasing trend ofprecipitation during autumn and decreasing trend dur-ing spring, while they disagree on the winter and summertrends. Trends fromNCEP/NCARR1meteorological reanal-ysis [41] and trends from our study disagree during all sea-sons, except for the autumn.

By the end of the 21st century it is expected that pre-cipitation in Slovenia will continue to decrease in summermonths (up to 20 %), increase in winter (up to 30%) andshow no significant changes in spring and autumn [42].Furthermore, results from high-resolution climate changesimulations over the MR showed substantial precipitationincreases in winter (>25%) and spring (from 10% to 25%)and a decrease in summer (from −10% to −25%) and asmall change in autumn precipitation (from −5% to 5%)in Slovenia by the end of the 21st century [43]. Comparedto these studies, our results showed significant drying dur-ing summer and non-significant changes during autumn,and this is compatible with model projections for the fu-ture. Observed winter and spring trends are not compati-ble with climate model projections.

Annual and seasonal precipitation in theMRshowsnouniform trend. Weak or non-significant trends for precipi-tation in the past century have been found at the Mediter-ranean scale [44], in Serbia [6], Israel [5], northwesternItaly [45], in the Alpine region [46], etc. Seasonal trendsindicate a slight decrease in winter and spring and an in-crease in autumnprecipitation in Serbia [6]. Lopez-Bustinset al. [14] noticed a significant decrease of winter rainfallat the Iberian Peninsula in its western and central areasthroughout the second half of the 20th century, whereasover the eastern fringe it showed little variation. Obtainedtrends in this study together with a projected future pre-cipitation decrease in the MR [2, 4] that is going to be mostpronounced in summer [3] could imply that these changeshave already started in Slovenia, which could lead to anincreased economic and social vulnerability in the coun-try due to reduced water availability in the future. Resultsfrom this study show drying in the spring and summerseasons as in the Coupled Model Intercomparison Projectphase 5 (CMIP5)models, but the observed trends are oppo-

site for winter and autumn seasons compared to the mod-eled trends. Observed trends also have higher valueswhencompared to the modeled trends [47].

Correlations between NAOi, MOi and annual and sea-sonal precipitation in Slovenia are negative. When NAOis in its positive phase, low-pressure anomalies over theIcelandic region and throughout the Arctic combine withhigh-pressure anomalies across the subtropical Atlantic toproduce stronger than average westerlies across the mid-latitudes. During a positive NAO, conditions are drier overthe MR [48], including Slovenia, as noticed in our study.The negative NAO index phase shows a weak subtropi-cal high and a weak Icelandic low. The reduced pressuregradient results in fewer and weaker winter storms cross-ing on a more west-east pathway and bringing moist airinto the Mediterranean [49] and increasing precipitationamounts into Slovenia. The positive mode of MO is relatedto anticyclonic conditions in the western Mediterraneanand a trough in the east, and with below-average rain-fall rates in the entire Mediterranean basin [50], includingSlovenia. In its negative mode, a low pressure region is lo-cated near the British Isles or north of the Iberian Penin-sula while anticyclonic conditions prevail in the Mediter-ranean. This situation is related with rainfall events in thewestern part of the Mediterranean basin [19]. Results fromour study indicate more precipitation in Slovenia duringthe positive MO phase. NAOi and MOi significantly influ-ence winter precipitation. In spring and autumn their sig-nificant influence is not registered, while in summer it islimited to a small area. Statistically significant correlationsare stronger for MOi than for NAOi.

Correlations between WeMOi and annual and sea-sonal precipitation in Slovenia are positive. The positivephase of theWeMO corresponds to an anticyclone over theAzores and low-pressures in the Liguria Gulf [20], resultingin higher precipitation amounts in the larger part of Slove-nia in all seasons except for summer when its influence isspatially limited. TheWeMOnegative phase coincideswitha central European anticyclone located north of Italy and alow-pressure centre in the framework of the Iberian south-west [20] leading to a precipitation decrease in Slovenia.

NAOi shows a positive and significant (at 95% level)trend in the second half of the 20th century [14]. The trendof this atmospheric circulation index is consistentwith thereduction in winter precipitation throughout Slovenia reg-istered in this paper and in the study of de Luis et al. [7],and over most of the Iberian Peninsula at the end of 20thcentury [14]. Also, NAOi displays a strong, negative corre-lation with winter [45] and spring precipitation in Italy [51]and at high altitudes in the Alps [46, 52]. Except withmeanprecipitation amounts, NAOi is negatively correlated

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with the frequency of extreme precipitation days over thenorthwesternMR in the period 1961-2000. The correlationsare rather small during autumn (October-November) butare quite considerable during the rest of the rainy season(December-January, February-March) [12].

MO is strongly linked in winter to NAO [19]. An ob-served increase in MOi during the second half of the 20thcentury [17, 19] led to smaller precipitation amounts southfrom 50°N [17] which is in accordance with a winter pre-cipitation decrease in Slovenia when its influence is thestrongest.

WeMOi is significantly reduced in winter throughoutthe second half of the 20th century [20] with WeMO enter-ing an extreme negative phase in the 1990s. This recentWeMOi decay leads to a rainfall reduction over the north-ern fringe of the Iberian Peninsula [14] and torrential rain-fall reduction in the northeastern Iberian Peninsula [21]. Asignificant increase in sea-level pressure in northern Italyhas been detected during the twentieth century [53] thatcould contribute to the precipitation decrease in Sloveniain all seasons except autumn. In autumn, a large increasein cyclone activity was identified in the Gulf of Genoa andthe southern part of the Adriatic Sea that could be respon-sible for the positive trend in autumn precipitation [54–56].

Results from this study contribute to a better under-standingof relationships betweenatmospheric circulationpatterns and precipitation variability in this transitionalarea. It is shown that the influence of NAO on precipitationvariability over Slovenia is smaller than the effects of theatmospheric circulations belonging to the Mediterraneanarea (namelyWeMOandMO).WeMOappeared as themostdominant atmospheric circulation pattern influencing an-nual and seasonal precipitation variability and distribu-tion in the Republic of Slovenia, except for winter whenMO is themost significant atmospheric circulationpattern.Relationships between other weather variables (e.g. tem-perature) and atmospheric circulation patterns could beinvestigated in future papers in order to acquire amore de-tailed picture of climatic change in this country.

Acknowledgement: This research is supported by theproject no. 43002 financed by the Ministry of Education,Science and Technological Development of the Republicof Serbia.

References[1] Lionello P., Abrantes F., Gacic M., Planton S., Trigo R., Ulbrich

U., The climate of the Mediterranean region: research progressand climate change impacts. Reg. Environ. Change, 2014, 14,1679-1684

[2] Jacobeit J., Hertig E., Seubert S., Lutz K., Statistical downscal-ing for climate change projections in the Mediterranean region:methods and results. Reg. Environ. Change, 2014, 14, 1891-1906

[3] DubrovskýM., HayesM., Duce P., TrnkaM., SvobodaM., Zara P.,Multi-GCM projections of future drought and climate variabilityindicators for the Mediterranean region. Reg. Environ. Change2014, 14, 1907-1919

[4] IPCC Intergovernmental Panel on Climate Change, The PhysicalScience Basis, Summary for Policymakers (contribution of WG Ito the 4th Assessment Report of the IPCC), Cambridge and NewYork: Cambridge University Press, 2007

[5] Ziv B., Saaroni H, Pargament R., Harpaz T., Alpert P., Trends inrainfall regime over Israel, 1975–2010, and their relationshipto large-scale variability. Reg. Environ. Change, 2014, 14, 1751-1764

[6] Luković J., Bajat B., Blagojević D., Kilibarda M., Spatial patternof recent rainfall trends in Serbia (1961–2009). Reg. Environ.Change, 2014 14, 1789-1799

[7] de Luis M., Čufar K., Saz M.A., Longares L.A., Ceglar A., Kajfež-Bogataj L., Trends in seasonal precipitation and temperaturein Slovenia during 1951–2007. Reg. Environ. Change, 2014, 14,1801-1810

[8] Hurrell J.W., Decadal trend in the North Atlantic oscillation: re-gional temperature and precipitation. Science, 1995, 269, 676-679

[9] Hurrell J.W., Van Loon H., Decadal variations in climate associ-ated with the North Atlantic oscillation. Clim. Chang., 1997, 36,301-326

[10] Sušelj K., Bergant K., Mediterranean Oscillation Index. Geo-phys. Res. Abstr., 2006a, 8, 2145

[11] Sušelj K., Bergant K., Sredozemski oscilacijski indeks in vpliv napodnebje Slovenije [Mediterranean Oscilation index and its in-fluence on the climate of Slovenia]. In: Kozmus K, KuharM (Ed.),Raziskave s področja geodezije in geofizike: zbornik predavanj[Researches in geodesy and geophysics: collection of lectures].Faculty of Civil and Geodetic Engineering, 2006b, Ljubljana (inSlovenian)

[12] Krichak S.O., Breitgand J.S., Gualdi S., Feldstein S.B.,Teleconnection-extreme precipitation relationships overthe Mediterranean region. Theor. Appl. Climatol., 2014, 117,679-692

[13] Brunetti M., Maugeri M., Nanni T., Atmospheric circulation andprecipitation in Italy for the last 50 years. Int. J. Climatol., 2002,22, 1455-1471

[14] Lopez-Bustins J.A., Martin-Vide J., Sanchez-Lorenzo A., Iberiawinter rainfall trends based upon changes in teleconnectionand circulation patterns. Glob. Planet. Chang., 2008, 63, 171-176

[15] Conte M., Giuffrida S., Tedesco S., The Mediterranean oscilla-tion: impact on precipitation and hydrology in Italy. In: Proceed-ings of the Conference on Climate and Water, Vol. 1. Publica-tions of Academy of Finland, Helsinki, 1989, 121-137

Brought to you by | University of MariborAuthenticated

Download Date | 3/2/17 1:46 PM

604 | Dragan D. Milošević et al.

[16] Palutikof J.P., Analysis of Mediterranean climate data: mea-sured and modelled. In: Mediterranean Climate-Variability andTrends, Bolle HJ (ed.). Springer-Verlag, Berlin, 2003, 133-153

[17] Piervitali E., Colacino M., Conte M., Signals of climatic changein the central–western Mediterranean basin. Theor. Appl. Cli-matol., 1997, 58, 211-219

[18] Kutiel H., Paz R., Sea level pressure departures in the Mediter-ranean and their relationship with monthly rainfall conditionsin Israel. Theor. Appl. Climatol., 1998, 60, 93-109

[19] Dünkeloh A., Jacobeit J., Circulation dynamics of Mediterraneanprecipitation variability 1948–98. Int. J. Climatol., 2003, 23,1843-1866

[20] Martín-Vide J., Lopez-Bustins J.A., The Western MediterraneanOscillation and rainfall in the Iberian Peninsula. Int. J. Climatol.,2006, 26(11), 1455-1475

[21] Martin-Vide J., Sanchez-Lorenzo A., Lopez-Bustins J.A., Cor-dobilla M.J., Garcia-Manuel A., Raso J.M., Torrential Rainfallin Northeast of the Iberian Peninsula: Synoptic patterns andWeMO influence. Advances in Science and Research, 2008, 2,99-105

[22] Orožen Adamič M., About Slovenia. In: Orožen Adamič M (Ed.),Slovenia: a geographical overview. ZRC SAZU, Ljubljana, 2004,7-9

[23] Ogrin D., Prut D. Aplikativna fizična geografija Slovenije [Ap-plicative physical geography of Slovenia]. Znantstvena založbaFikozofske fakultete, Ljubljana, 2009, 13. (in Slovenian)

[24] Perko D., The regionalization of Slovenia. Geografski zbornik,1998, 38, 12-57

[25] Ogrin D.,Modern climate change in Slovenia. In: OroženAdamičM (Ed.), Slovenia: a geographical overview. ZRC SAZU, Ljubl-jana, 2004, 45-50

[26] Alexandersson H., A homogeneity test applied to precipitationdata. J. Climate, 1986, 6, 661-675

[27] Khaliq M.N., Ouarda T., On the critical values of the standardnormal homogeneity test (SNHT). Int. J. Climatol., 2007, 27, 681-687

[28] Štěpanek P., AnClim - software for time series analysis. Depart-ment of Geography, Faculty of Natural Sciences, MU, Brno, 1.47MB, 2007 http://www.climahom.eu/AnClim.html

[29] Sneyers R., On the statistical analysis of series of observations.World Meteorological Organization, Technical Note, Genève,1991, 415, 192

[30] Salmi T., Mättä A., Anttila P., Ruoho-Airola T., Amnell T., Detect-ing trends of annual values of atmospheric pollutants by theMann-Kendall test and Sen’s slope estimates. The Excel tem-plate application MAKESENS. Finnish Meteorological Institute,Helsinki, 2002, 1-35

[31] National Oceanic and Atmospheric Association (NOAA) ClimatePrediction Center (CPC) website, 2014 http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml

[32] Climatic Research Unit website, 2014 http://www.cru.uea.ac.uk/cru/data/moi/

[33] University of Barcelona website, 2014 http://www.ub.edu/gc/English/wemo.htm

[34] Savić S.,Milovanović B., Lužanin L., Lazić L., Dolinaj D., The vari-ability of extreme temperatures and their relationship with at-mospheric circulation: the contribution of applying linear andquadratic models. Theor. Appl. Climatol., 2015, 121, 591-604

[35] Savić S., Petrović P., Milovanović B., Homogenisation of meanair temperature data series from Serbia. European Geosciences

Union-General Assembly, Vienna, Austria, 2010, GeophysicalResearch Abstract Vol. 12, EGU2010-5521-1

[36] Moberg A., Alexandersson H., Homogenization of Swedish tem-perature data. Part II: homogenized gridded air temperaturecompared with a subset of global gridded air temperature since1861. Int. J. Climatol., 1997, 17, 35-54

[37] Fernandez J., Sáenz J., Zorita E., Analysis of wintertime atmo-spheric moisture transport and its variability over southern Eu-rope in the NCEP reanalyses. Clim. Res., 2003, 23, 195-215.

[38] Bojariu R., Giorgi F., The North Atlantic Oscillation signal in a re-gional climate simulation for the European region. Tellus, 2005,57A(4), 641-653.

[39] HaylockM.R., Hofstra N., Klein Tank A.M.G., Klok E.J., Jones P.D.,New M., A European daily high-resolution gridded dataset ofsurface temperature and precipitation. J. Geophys. Res (Atmo-spheres), 2008, 113, D20119, doi:10.1029/2008JD10201

[40] Dee D.P., Uppala S.M., Simmons A.J., Berrisford P., Poli P.,Kobayashi S., AndraeU., BalmasedaM.A., BalsamoG., Bauer P.,Bechtold P., Beljaars A.C.M., van de Berg L., Bidlot J., BormannN., Delsol C., Dragani R., Fuentes M., Geer A.J., Haimberger L.,Healy S.B., Hersbach H., Hólm E.V., Isaksen L., Kållberg P., Köh-ler M., Matricardi M., McNally A.P., Monge-Sanz B.M., MorcretteJ.-J., Park B.-K., Peubey C., de Rosnay P., Tavolato C., ThépautJ.-N., Vitarta F., The ERA-Interim reanalysis: configuration andperformance of the data assimilation system. Q. J. Roy. Meteor.Soc., 2011, 137, 553-597.

[41] Kalnay E., Kanamitsu M., Kirtler R., Collins W., Deaven D.,Gandin L., Iredell M., Saha S., White G., Woollen J., Zhu Y.,Chelliah M., Ebisuzaki W., Higgins W., Janowiak J., Mo K.C., Ro-pelewski C., Wang J., Leetma A., Reynolds R., Jenne R., JosephD., The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Me-teorol. Soc., 1996, 77, 437-471.

[42] Bergant K., Projections of Climate Change for Slovenia. In: JurcM (Ed.), Climate Change: impact on forests and forestry. Studiaforestalia Slovenica, 130, 67-86.

[43] Gao X., Pal J.S., Giorgi F., Projected changes in mean and ex-treme precipitation over the Mediterranean region from a highresolution double nested RCM simulation. Geophys Res Lett,2006, 33, L03706, DOI:10.1029/2005GL024954.

[44] Norrant C., Douguedroit A., Monthly and daily precipitationtrends in the Mediterranean (1950–2000). Theor. Appl. Clima-tol., 2006, 83, 89-106

[45] Ciccarelli N., vonHardenberg J., Provenzale A., Ronchi C., VargiuA., Pelosini R., Climate variability in north-western Italy duringthe second half of the 20th century. Glob. Planet. Chang., 2008,63, 185-195

[46] Beniston M., Mountain climates and climatic change: anoverview of processes focusing on the European Alps. Pure andApplied Geophysics, 2005, 162, 1587-1606

[47] Kelley C., Ting M., Seager R., Kushnir Y., Mediterraneanprecipitation climatology, seasonal cycle, and trend assimulated by CMIP5. Geophys Res Lett, 2012, 39, 21,DOI:10.1029/2012GL053416

[48] Visbeck M.H., Hurrell J.W., Polvani L., Cullen H.M., The North At-lantic Oscillation: past, present, and future. Proc. Natl. Acad.Sci. U.S.A., 2001, 98, 23, 12876-12877.

[49] Rousi E., C. Anagnostopoulou C., Tolika K.,Maheras P., BloutsosA., ECHAM5/MPI General CirculationModel Simulations of Tele-connection Indices over Europe. In: Helmis CG (Ed.), AdvancesinMeteorology, Climatology andAtmospheric Physics. Springer

Brought to you by | University of MariborAuthenticated

Download Date | 3/2/17 1:46 PM

Variability of seasonal and annual precipitation in Slovenia | 605

Berlin Heidelberg, 709-715.[50] Angulo-Marti?nez M., Santiago Begueri?a S., Do atmospheric

teleconnection patterns influence rainfall erosivity? A study ofNAO, MO and WeMO in NE Spain, 1955-2006, J. Hydrol., 2012,450- 451, 168-179.

[51] Wibig J., Precipitation in Europe in relation to circulation pat-terns at the 500 hPa level. Int. J. Climatol., 1999, 19, 253-269

[52] Beniston M., Jungo P., Shifts in the distributions of pressure,temperature and moisture and changes in the typical weatherpatterns in the Alpine region in response to the behavior of theNorth Atlantic Oscillation. Theor. Appl. Climatol., 2002, 71, 29-42

[53] Maugeri M., Brunetti M., Monti F., Nanni T., Sea-level pressurevariability in the Po plain (1765–2000) from homogenized dailysecular records. Int. J. Climatol., 2004, 24, 437-455

[54] Bartholy J., Pongracz R., Pattanyus-Abraham M., Analysing thegenesis, intensity and tracks of western Mediterranean cy-clones. Theor. Appl. Climatol., 2009a, 96, 133-144

[55] Bartholy J., Pongracz R., Pattanyus-Abraham M., European cy-clone track analysis based on ECMWF ERA-40 data sets. Int. J.Climatol., 2009b, 26, 1517-1527

[56] Lionello P., Zardini, Characteristics of the cyclonic activity in theMediterranean sea during the last four decades of the 20th Cen-tury. Geophys. Res. Abstr., 2003, 5, 8316

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