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We present the first evaluation of the wind field from the CORDEX-FPS ensemble of kilometer-scale simulations, with focus on the Adriatic region. Kilometer-scale climate models, also known as convection-permitting models (CPMs), produce a good representation of small-scale topographic features and consequently a more detailed depiction of dynamical and thermal circulation. These enable a reliable view of climate characteristics of the wind field, especially in coastal regions and over complex terrain, such as the Adriatic. We investigate the (potential) added value introduced by CPMs compared to classical “cumulus-parametrized” regional climate models (RCMs), reanalysis and station observations. For this purpose, wind components at 10 meter level are used at 3-hourly frequency. All simulations cover a 10-year period, extending from 2000 to 2009. In terms of the standard statistical parameters such as correlation coefficient and temporal standard deviation, CPMs are very dependent on their parent RCM performance. However, the orographic forcing emphasizes the potential added value and CPMs contain some fine spatial scale variability (i.e. stronger extremes by 25% and accurate wind direction) that is absent in coarser RCMs and reanalysis. The potential added value is higher in the cold season compared to the warm season due to the proportion of severe wind events. CPMs reproduce well the typical wind regimes along the Adriatic coast, namely Bora and Sirocco. The benefit of using CPMs is especially pronounced in simulating Bora maximum wind speeds in northern Adriatic and Sirocco frequencies in southern Adriatic. Based on our overall analysis, we conclude that CPMs provide added value compared to coarser models, especially in the complex coastal terrain.

Since changes in temperature and precipitation have different effects on (i) all developmental stages of grapevines in most of the wine regions worldwide (i.e., on their phenological characteristics) and (ii) different varieties, a comprehensive database of bioclimatic indices has been calculated and analyzed for Croatian wine producing regions. The database consists of theaverage growing season temperature, Growing degree-days, Huglin index, Dryness index, and Cool night index that are based on all available meteorological measurements as well as the outputs of regional climate models (RCMs) from the EURO-CORDEX database. The horizontal grid spacing of 0.11° from the RCM ensembles enabled a fine-scale determination of bioclimatic indices for the present and future climate in Croatia. In addition, statistical analyses (standard statistical parameters and Bayesian method) were done to examine trends in sugar content, total acidity and date of harvest. Calculations were performed for the present and future climate on the basis of data from seven selected vineyards/wineries and four varieties (‘ Graševina’, ‘Plavac mali’, ‘Chardonnay’, and ‘Merlot’). The results show whether the part of Croatia that is suitable for grape cultivation in the present climate will continue to be favorable in the future within the Mediterranean area. In general, projections suggest further warming and drying of the climate in Croatia and an earlier harvest, with some variations among varieties that show latitude dependence. Projections for the future climate also suggest that the existing viticultural zoningwill be much less adequate for the Croatian territory because it reduces the economically sustainable production of wine in certain areas.

In this study, an investigation of a new thunderstorm intensity index (TSII) derived from lightning data is performed, along with its relationship to rain, wind, hail and waterspouts as well as instability indices (CAPE, LI, KI, and DLS). The study area is located in the northeastern Adriatic and includes various terrain types in a relatively small area (coastal, flatlands, hills and valleys, and mountain regions). The investigated period covers 11 years (2008–2018). The mathematical algorithm standing behind the TSII is based on the well-established methodology of lightning jump, allowing us to recognize areas where intensification in thunderstorms occurred. Our results suggest that these areas (with a positive TSII) experience significantly higher rain intensities and have higher total amounts of precipitation compared with areas where thunderstorms did not generate a TSII. Moreover, 76% of thunderstorm hail cases were associated with the presence of a TSII within a 15 km distance. The maximum reported wind speed also has higher values on a day with a TSII. Out of 27 waterspout events associated with lightning, 77% were related to a TSII. Due to the good spatial (3 km × 3 km) and high temporal (2 min) resolution of lightning data, the TSII can recognize even a local and short-lived intense system that is often misread by radars and satellites due to their inferior temporal resolution. The TSII is designed to be used as a climatological and diagnostic variable that could serve in lieu of more established data sources (e.g., station measurements and observations, radar imagery, etc.) if they are unavailable.

Lightning data provide very high spatial and temporal resolution allowing us to decompose thunderstorms into smaller segments. By using those segments we introduce a new Thunderstorm Intensity Index (TSII). Based on the mathematical background of lightning jump, TSII aims to identify the area which is most affected by the storm. Such index captures location in space and time where a thunderstorm experienced a sudden positive change in lightning activity, using the Eulerian standpoint. The advantage is independence to total number of flashes produced by the storm (which can vary significantly), and high temporal monitoring (2 min). An ongoing research (within SWALDRIC project) is performed on period of 11 years of lightning data and in a study area of NE Adriatic region. Validation is done against precipitation, wind, hail, waterspouts and comparison with ERA5 instability indices is made. Results show very good agreement between higher rain intensities and total precipitation in vicinity of TSII. Good agreement with hail occurrence, waterspout presence and wind gusts within 15km radius. Also, TSII turned to be invariant to the size of the system, thus allowing us to recognise small scale intense thunderstorms.

Thunderstorm Intensity Index (TSII) is a new method of determining locations over which thunderstorms exhibited intense lightning activities. It follows changes in flash rates in a single point (3x3 km) in short time intervals (2 min) using mathematical principles of lightning jump. Contrary to lightning jump, TSII is an diagnostic tool for detection of intense storms and affected areas. One intense storm will usually produce values of TSII between 1 and 3 per affected point depending on the intensity of the storm. End result is a trail of intense parts of the storm.

General awareness and overall interest regarding hailstorms and hail properties in Europe have increased significantly in the last several decades and have resulted in numerous local, national, and even Europe-wide studies on hail and hail properties. To contribute to this field, we determined the hail climatology in the northeastern (NE) Adriatic region and analyzed its spatial and temporal patterns and performed an objectively derived weather type analysis of ERA5 daily mean data and instability indices. We studied the NE Adriatic region due to its focus on agricultural activities and on quality wine production. Our results are based on approximately 60 years of high- spatial-resolution measurements collected from 27 stations across complex terrain. The results show (i) high levels of spatial variability, (ii) significant annual variations, and (iii) hail throughout the whole year that (iv) intensifies in summer months. Furthermore, redistribution of hail among seasons (in particular, from summer to spring) was detected. Most significant changes were visible in the June to October period, with a negative trend of -0.06 hail days/year, and the period from November to March exhibited a positive trend of 0.13 hail cases/year. We found that deep cyclonic systems in front of and above our domain were most responsible for hail generation, often supported by southwesterly winds. Additionally, the vast majority of observed hail events occurred in unstable and sheared environments.

Focus area in this study is the Adriatic region where several near-surface (i.e. 10 m) wind regimes impact daily human activities and characterize local climate. We examine 10 m wind speed changes in the EURO-CORDEX regional climate models’ (RCMs’) projections, and how they are linked with the newly defined weather types based on the location of the synoptic centers relative to the Adriatic region. RCMs used in this study are SMHI-RCA4 and DHMZ-RegCM4.2, forced by 5 (4) CMIP5 global climate models under historical, RCP4.5 and RCP8.5 greenhouse gasses concentrations. The weather type algorithm considers daily mean sea level pressure and 500 hPa geopotential height data to define one out of 16 possible weather types that are relevant for the generation of the two main winds over this region, namely Bora and Sirocco. Finally, for the each grid cell inside our focus area, distribution of the Bora and Sirocco days is based on the each weather type, for both historical (1971-2000) and future (2041-2070) time periods. We limit in this presentation on the Bora-related mechanisms. For the winter season, RCM projections indicate reduction in the main cyclonic types relevant for the Bora formation over the entire Adriatic. In contrast, for the summer season, increase in the main anticyclonic Bora-related weather types is found in the RCM ensemble over the northern Adriatic.

The factors which significantly affect the viticulture are temperature and precipitation. Consequently, viticulture is highly affected by climate change. The agroclimatic indices describe the suitability of particular region for wine production. For the purpose of this study six indices (Average growing season temperature, Growing degree days, Huglin index, Dryness index, Cool night index and Composite index) were calculated using daily output from three CORDEX Regional Climate Models’ (RCMs) simulations (CLMcom-CCLM4-8-17, SMHI-RCA4, CNRM-ALADIN5.3) for Croatian domain and using daily near-surface measurements (minimum, maximum and mean temperature, relative humidity, wind speed and total precipitation). All RCMs are forced by Global Climate Models (GCMs) with a moderate (RCP4.5) and a high-end (RCP8.5) greenhouse gass (GHG) scenario. All the simulations have horizontal grid spacing of 0.11◦. First historical analysis was done comparing two periods (1961-1990 and 1988-2017) to establish present situation and to determine changes in indices so far. Then, in order to determine future changes in agroclimatic indices, spatial distribution of the indices in historical runs (1971-2000) is compared to three different 30-year periods (2011-2040, 2041-2070 and 2070-2099). The sign and the robustness of future changes depend on the location/region analyzed. The results revealed good skill of the RCM in simulating bioclimatic characteristics. The results also show, whether the part of the country, which is suitable for grape cultivation in present climate (1971-2000) continues to be favorable in the future. We can also reveal whether some other parts of Croatia become suitable for cultivating grapevine in the future climate.

Almost every sufficiently developed convective storm has been accompanied by significant lightning activity. Such storms are often characterized by rain showers, wind gusts and / or hail, but given the spatial and temporal scales of the storms themselves, these phenomena often go unnoticed. In contrast to them with a special focus on the lightning, lightning activity is very successfully followed by lightning detection networks that are very widespread today and offer us very high spatial and temporal resolution. A few years ago, solid link between the dynamics of lightning and the occurrence of hail, wind gusts and tornado was established. This connection is manifested in the rapid rise of lightning activity "eng. Lightning jump" approximately 10 minutes before observing one of the occurrences. So far the method has been successfully used in "Nowcasting", and this presentation will show the first attempts to apply such method to the LINET network archive data for the period from 2008 to 2015 for the territory of Croatia. Verification of method will be done over territory of Istrian County with the aim of extracting climatological features of hail. This climatological approach opens the possibility to analyse hail but also other extremes associated with convection primarily in areas not covered by radar but also in other areas as a kind of verification tool. Further more, this method can cover far greater distances than other remote measurements such as radars or satellites that cover equivalent areas but offer a relatively rough resolution compared to resolution of lightning.

The potential environmental impacts on grapevine yield, sugar and acidity can be very diverse depending on heat and available water in changing climate. Due to the strong dependence of vines on atmospheric conditions, a set of bioclimatic indices has been developed and used in many studies to combine meteorological and grape cultivation information in a quantitative manner. The set mainly consist average temperature growing season (TGS), Growing degree-days (GDD or WI), Huglin Index (HUI), Dryness index (DI), Cool night index (CI). Although many authors calculated these indices for the specific locations, new grided meteorological datasets created from measurements and/or regional climate models (RCMs from EURO-CORDEX) enabled spatial analysis of these indices which allow the viticultural zoning of larger regions. Since changes in temperature and humidity will act (i) differently on all developmental stages of vines in certain wine growing areas (i.e. on their phenological characteristics) and (ii) differently on different varieties, a comprehensive database of bioclimatic indices has been calculated and analysed using all available meteorological and agronomic measurements as well as the results of RCMs. The horizontal grid spacing of 0.11° enabled fine determination of bioclimatic indices for present and future climate in Croatia. In addition, statistical analyses have been done examining sugar content and total acidity and date of harvest in the present and future climate from selected wineries and selected varieties. The results show whether the part of the country, which is suitable for grape cultivation in present climate, continues to be favourable in the future. The spatial distributions in the future climate also suggest that the existing zoning of wine-growing areas is not adequate for the Croatian territory.

Severe convective storms are a primary cause of catastrophic loss through property damage and life-threatening weather conditions. These events are characterized by the presence of heavy convective storms, lightning that can initiate wildfires, strong and damaging winds (e.g., wind gusts), as well as heavy rain that can cause flash floods and hail. Due to sparse observations and inability of conventional climate models to represent these local weather phenomena, our understanding of severe weather events and their response to a changing climate is still very limited. Advances in computational power and recent developments in atmospheric modeling have enabled the use of climate models at kilometer scale horizontal resolutions. These so-called convection-resolving models (CRMs) resolve deep convective events such as thunderstorms and rain showers. Such models have been used for numerical weather forecasting purposes for over a decade. Although these models improve the simulation of heavy precipitation, their application for climate studies and the analysis of severe convective events, like lightning, hail and severe winds, has been very limited. The SWALDRIC project investigate severe weather events over Europe, with a specific focus on the Alpine and Adriatic region. The main goals of the study are to better understand severe weather events, to evaluate their representation in weather and climate models, and to investigate their response to climate change. Key elements of the proposal are: The exploitation of a unique Croatian hail-pad data set, the exploration and intercomparison of a wide range of different atmospheric (weather and climate) modeling systems, and the use of kilometer-scale pan-European decade-long simulations using the first regional climate modeling framework able to run entirely on Graphics Processing Units (COSMO-GPU).

Near-surface wind over the Adriatic region are examined under present-day and future climate conditions for two greenhouse gas scenarios (RCP4.5 and RCP8.5) with an ensemble of high- resolution (0.11˚) CORDEX simulations. The influence of particular combinations of regional climate models (RCMs) and global climate models (GCMs) and emission scenarios on the future changes in the near-surface wind field has been explored in more detail. Starting with the seasonal climate change signal in large-scale flow over the entire CORDEX domain, we focus to regional daily wind fields over the Adriatic domain and subdaily features of well-known regional winds (Bora and Sirocco winds). The analysis reveals the strong sensitivity of the climate change signal in the simulated wind flow to (i) the choice of the GCM that provides the boundary conditions and (ii) the analyzed locations across the Adriatic region. The results of the 21st century projections indicate that the changes in synoptic activity have an impact on the wind field at the (sub)daily time scale. We found a reduction in the number of Bora events and increase in the number of Sirocco events in northern Adriatic during the winter season, with an increase in pressure in the middle of the 21st century. Overall, the mean wind speed during Bora and Sirocco events is reduced, except for Bora in northern Adriatic. For the summer season, we found a large increase in the number of thermally induced flows, which is probably caused by the weakening of the Azores High.

Statistical downscaling methods (SDMs) are techniques used to downscale and/or bias correct climate model results to regional or local scales. The European network VALUE developed a framework to evaluate and intercompare SDMs. One of VALUE’s experiments is the perfect predictor experiment that uses reanalysis predictors to isolate downscaling skill. Most evaluation papers for SDMs employ simple statistical diagnostics and do not follow a process-based rationale. Thus, in this paper, a process-based evaluation has been conducted for the more than 40 participating model output statistics (MOS, mostly bias correction) and perfect prognosis (PP) methods, for temperature and precipitation at 86 weather stations across Europe. The SDMs are analysed following the so-called “regime- oriented” technique, focussing on relevant features of the atmospheric circulation at large to local scales. These features comprise the North Atlantic Oscillation, blocking and selected Lamb weather types and at local scales the bora wind and the western Iberian coastal-low level jet. The representation of the local weather response to the selected features depends strongly on the method class. As expected, MOS is unable to generate process sensitivity when it is not simulated by the predictors (ERA- Interim). Moreover, MOS often suffers from an inflation effect when a predictor is used for more than one station. The PP performance is very diverse and depends strongly on the implementation. Although conditioned on predictors that typically describe the large- scale circulation, PP often fails in capturing the process sensitivity correctly. Stochastic generalized linear models supported by well- chosen predictors show improved skill to represent the sensitivities.

Jadran je područje kompleksne topografije i stoga predstavlja izazov za realistično simuliranje polja vjetra regionalnim klimatskim modelima. Analizirani regionalni klimatski modeli uključuju modele CORDEX inicijative s prostornim korakom od 0.11° i 0.44° te ETH instituta u Zürichu inicijative s prostornim korakom od 0.11° i 0.02°. Simulirani prizemni vjetar usporedit će se s prizemnim vjetrom iz standardne mreže kopnenih meteoroloških postaja, iz QuikSCAT satelitskih mjerenja te ERA-Interim reanalize za šire područje Jadrana. U svrhu evaluacije koristit će se nekoliko osnovnih (pristranost, koeficijent korelacije, standardna devijacija), izvedenih (mjere uspješnosti) i naprednih (EOF analiza i spektralna analiza) statističkih parametara. Ovo je rezultiralo procjenom ograničenja u simuliranju strujanja u današnjoj generaciji regionalnih klimatskih modela. Pokazano je da regionalni klimatski modeli vjerno simuliraju tipične vjetrovne režime u Jadranu te pokazuju dodanu vrijednost smanjenjem prostornog koraka mreže, osobito u obalnom području i kod ekstremnih brzina vjetra. Promjene u prizemnom vjetru odredit će se usporedbom polja strujanja u sadašnjoj i budućoj klimi iz CORDEX simulacija s prostornim korakom od 0.11°. Analizirat će se utjecaj izbora regionalnog klimatskog modela, rubnih uvjeta i scenarija koncentracija stakleničkih plinova (RCP4.5 i RCP8.5), a rasap među simulacijama bit će mjera vjerojatnosti nekog događaja. Polje strujanja analizirat će se zasebno u smislu promjena u razdiobi brzina vjetra i smjeru vjetra duž Jadrana. Izraziti fokus bit će na smjerovima vjetra koji odgovaraju buri i jugu. Analiza je pokazala da se buduće promjene intenziviraju odabirom jačeg (RCP8.5) scenarija i približavanjem kraju 21. stoljeća. Buduće su promjene često istog reda veličine kao i interkvartilni raspon, međutim postoje naznake da će se broj događaja i srednja brzina vjetra u zimskom periodu bure prema kraju stoljeća smanjiti, a u ljetnom povećati. Za jugo je pokazano da broj događaja i srednja brzina vjetra opadaju, ali raste 99. percentil brzine vjetra. Nakon toga će se istražiti i promjene u polju tlaka i geopotencijala te će se promotriti buduće promjene u ciklonalnoj i anticiklonalnoj aktivnosti nad Jadranom. Buduće promjene u buri i jugu pokušat će se povezati s promjenama u osnovnim sinoptičkim sustavima (ciklone, anticiklone) kroz algoritam za određivanje tipova vremena na sinoptičkoj skali nad širim Jadranskim područjem. Algoritmom je potvrđeno da se broj ciklona nad Jadranom, osobito zimi, smanjuje, a jača anticiklonalno strujanje.