Search

The accuracy of the climate impact models depends on the representative power of the climate model used in the analysis. Many problems in these impact models can be eliminated by the selection of the appropriate climate models as an input. The main purpose of this research is to find a methodology to select the more representative climate models. In recent years, the quantity and quality of climate models have significantly improved. In several projects, many different Global Climate Model (GCM)–Regional Climate Model (GCM) combinations have been carried out. One of these recent comprehensive projects is CORDEX. The monthly temperature outputs of various GCM-RCM combinations over Europe between the years 1976 and 2005 were used in this paper for the determination of the more representative combinations. E-OBS is used as the observation data set in this research. Using the proposed method, a clear difference between the more, moderately, and less representative model combinations could be obtained. To model the future temperature climatology of Europe, the best choice of the analysis method is using MPI as GCM and either REMO or CCLM5 as RCM over the whole domain. According to our analysis, the best representative climate model combination can be performed by running MPI-CCLM5 combination over the EURO-CORDEX domain. [ABSTRACT FROM AUTHOR]

Tropospheric humidity inversions are an important component of the Earth's climate system as well as a significant factor affecting the global radiation budget and cloud formation. Their occurrence enlarges the amount of downward longwave radiation trapped near the Earth's surface and provides moisture to maintain the top of clouds from evaporation. The aim of this paper is to examine the spatiotemporal variability of the humidity inversions over Europe. For the first time, we provide also a comprehensive analysis of relations between the humidity inversions and temperature inversions over the domain considered. The study is based on data derived from the ERA-Interim reanalysis for the period 1981–2015. We have confirmed that the temporal and spatial variability of the humidity inversions is strongly related to inversion type. The mean seasonal frequency of surface-based humidity inversions (SBHI) usually does not exceed 20%, while the mean seasonal frequency of elevated humidity inversions (EHI) ranges from 5 to 60% depending on the region and season. On average, EHI are substantially deeper and stronger than SBHI. We found also that the low-tropospheric humidity inversions often occur simultaneously with the temperature inversions. Moderate positive correlations exist, however, only among the parameters (depth and strength) of the same inversion type, but not between the humidity inversions and the temperature inversions. Considering the links between EHI and ETI (elevated temperature inversions) parameters, slightly higher values of the Spearman's rank correlation coefficient (ρs > 0.50) are found between EHI base height and ETI base height. Nonetheless, the simultaneous occurrence of EHI and ETI usually fosters the intensity of both inversion types. [ABSTRACT FROM AUTHOR]

This paper presents the results of the analysis of the Western Sudetes' snow cover temporal and spatial changes, as well as it demonstrates the research on the long-term trends in the changes of snow cover durability. In order to conduct the study, the coefficient of snow cover durability (V) was used, which was defined as the quotient of the actual and the potential time of snow cover duration and expressed in percentage (1–100%). Moreover, the frequency of total disappearance of snow cover was established for the optimal winter season (December–March). Measurement data were obtained from 17 stations in the 1961–2015 period. The snow cover on the Western Sudetes' slopes with southern (S) macro-exposure lasts longer (has greater durability) than on the slopes in analogous altitude zones with northern (N) macro-exposure. At the altitudinal level of 600–700 m a.s.l., where the differences are the biggest, the average V values range from 60% at stations N to 75% in stations S. In the analysed area, excluding the upper ranges, slight negative trends in V changes have been noted. Snow cover persists for a shorter and shorter time. For the substantial majority of the stations, the trends in these changes are not statistically significant at the 0.05 level of statistical significance. They refer to the tendencies in other mountainous regions in Poland and Europe. Analogously, the stations with S macro-exposure, located at similar altitudes as stations with N macro-exposure, are characterised by two to three times lesser frequency of total disappearance of snow cover. Coefficient V is negatively correlated with the total disappearance of snow cover. At the stations with S macro-exposure in the Western Sudetes, these correlations are usually strong or very strong, whereas at the stations with N macro-exposure, at similar altitudes, they are usually moderate or very weak. [ABSTRACT FROM AUTHOR]

The impacts of climate change are of primary importance for economic sectors whose proper operation greatly depends on climatic conditions; this is particularly true for beach tourism. Knowledge on climate preferences of tourists is essential for estimating the effects of changes in future climate to the climatic comfort of tourists, and consequently on their willingness to travel to specific destinations. In Southern Europe, changes of future temperature and precipitation are expected to be prominent but empirical studies on tourists' climate preferences are still limited. The paper presents the results of a recent survey carried out on 13 Greek islands among beach tourists during high season (summer), conducted through questionnaires completed mainly at the beach but also at airports and hotels. Findings reveal that precipitation is a crucial climatic parameter for beach tourism, while climate preferences of tourists differ to some extent according to demographic and other characteristics. Based on the statistical analysis of responses, a utility function was built for ambient temperature, rain, cloudiness, and wind, and the weights of these parameters were estimated. Finally, a Beach Utility Index (BUI) incorporating the estimated climatic utility functions is proposed. [ABSTRACT FROM AUTHOR]

Road authorities, freight, and logistic industries face a multitude of challenges in a world changing at an ever growing pace. While globalization, changes in technology, demography, and traffic, for instance, have received much attention over the bygone decades, climate change has not been treated with equal care until recently. However, since it has been recognized that climate change jeopardizes many business areas in transport, freight, and logistics, research programs investigating future threats have been initiated. One of these programs is the Conference of European Directors of Roads’ (CEDR) Transnational Research Programme (TRP), which emerged about a decade ago from a cooperation between European National Road Authorities and the EU. This paper presents findings of a CEDR project called CliPDaR, which has been designed to answer questions from road authorities concerning climate-driven future threats to transport infrastructure. Pertaining results are based on two potential future socio-economic pathways of mankind (one strongly economically oriented “A2” and one more balanced scenario “A1B”), which are used to drive global climate models (GCMs) producing global and continental scale climate change projections. In order to achieve climate change projections, which are valid on regional scales, GCM projections are downscaled by regional climate models. Results shown here originate from research questions raised by European Road Authorities. They refer to future occurrence frequencies of severely cold winter seasons in Fennoscandia, to particularly hot summer seasons in the Iberian Peninsula and to changes in extreme weather phenomena triggering landslides and rutting in Central Europe. Future occurrence frequencies of extreme winter and summer conditions are investigated by empirical orthogonal function analyses of GCM projections driven with by A2 and A1B pathways. The analysis of future weather phenomena triggering landslides and rutting events requires downscaled climate change projections. Hence, corresponding results are based on an ensemble of RCM projections, which was available for the A1B scenario. All analyzed risks to transport infrastructure are found to increase over the decades ahead with accelerating pace towards the end of this century. Mean Fennoscandian winter temperatures by the end of this century may match conditions of rather warm winter season experienced in the past and particularly warm future winter temperatures have not been observed so far. This applies in an even more pronounced manner to summer seasons in the Iberian Peninsula. Occurrence frequencies of extreme climate phenomena triggering landslides and rutting events in Central Europe are also projected to rise. Results show spatially differentiated patterns and indicate accelerated rates of increases. [ABSTRACT FROM AUTHOR]

Coupled atmosphere-ocean general circulation models (GCMs) simulate different realizations of possible future climates at global scale under contrasting scenarios of land-use and greenhouse gas emissions. Such data require several additional processing steps before it can be used to drive impact models. Spatial downscaling, typically by regional climate models (RCM), and bias-correction are two such steps that have already been addressed for Europe. Yet, the errors in resulting daily meteorological variables may be too large for specific model applications. Crop simulation models are particularly sensitive to these inconsistencies and thus require further processing of GCM-RCM outputs. Moreover, crop models are often run in a stochastic manner by using various plausible weather time series (often generated using stochastic weather generators) to represent climate time scale for a period of interest (e.g. 2000 ± 15 years), while GCM simulations typically provide a single time series for a given emission scenario. To inform agricultural policy-making, data on near- and medium-term decadal time scale is mostly requested, e.g. 2020 or 2030. Taking a sample of multiple years from these unique time series to represent time horizons in the near future is particularly problematic because selecting overlapping years may lead to spurious trends, creating artefacts in the results of the impact model simulations. This paper presents a database of consolidated and coherent future daily weather data for Europe that addresses these problems. Input data consist of daily temperature and precipitation from three dynamically downscaled and bias-corrected regional climate simulations of the IPCC A1B emission scenario created within the ENSEMBLES project. Solar radiation is estimated from temperature based on an auto-calibration procedure. Wind speed and relative air humidity are collected from historical series. From these variables, reference evapotranspiration and vapour pressure deficit are estimated ensuring consistency within daily records. The weather generator ClimGen is then used to create 30 synthetic years of all variables to characterize the time horizons of 2000, 2020 and 2030, which can readily be used for crop modelling studies. [ABSTRACT FROM AUTHOR]

The paper focuses on exceptionally hot summers (EHS) as a manifestation of contemporary climate warming. The study identifies EHS occurrences in Central and Eastern Europe and describes the characteristic features of the region's thermal conditions. Average air temperatures in June, July and August were considered, as well as the number of days with maximum temperatures exceeding 25, 30 and 35 °C, and with a minimum temperature greater than >20 °C, as recorded at 59 weather stations in 1951-2010. Extremely hot summers are defined as having an average temperature equal to or greater than the long-term average plus 2 SD. A calendar of EHSs was compiled and their spatial extent identified. The region experienced 12 EHSs, which occurred in a given year at 5 % or more stations (1972, 1981, 1988, 1992, 1997, 1998, 1999, 2002, 2003, 2006, 2007 and 2010). The EHS frequency of occurrence was found to be clearly on an increase. Indeed, only one EHS occurred during the first 30 years, but these occurred five times during the last 10 years of the study period. Their geographical extent varied both in terms of location and size. EHSs were observed at 57 out of the total of 59 weather stations in the study (the exceptions were Pecora and Cluj). The average air temperature of EHSs tended to exceed the relevant long-term average by 2-4 °C. The summer of 2010 was among the hottest (temperature anomaly 5.5-6 °C) and spatially largest. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the thunderstorm climate of the Baltic countries during the period of 1951-2000. Our study area is in northeastern Europe and encompasses Estonia, Latvia, and Lithuania. Visual thunderstorm observations at 59 weather stations were used as a data source. The mean annual number of thunderstorm days was 12-29.5. The seasonal cycle of thunderstorm hours with a daily step unexpectedly showed two maxima, whereas the monthly numbers of thunderstorm days had one clear mid-latitude specific peak between June and August. The diurnal cycle of thunderstorm hours showed a peak between 1400 and 1800 local time and a minimum between 0400 and 1000 hours local time. The average annual duration of thunderstorm events was 112 min. The average number of thunderstorm events per thunderstorm day was around 1.1-1.2. Our results showed that the thunderstorm climate of the Baltic countries generally resembles that of other mid-latitude study sites. [ABSTRACT FROM AUTHOR]

Characterizing climatic changes in the high-altitude mountain regions helps scientists and policy makers understand the effects of such changes on water resources, economic development, and the health of ecosystems. This paper proposes a change-point analysis to determine the time and magnitude of summer temperature changes in the summit areas of Romanian Carpathians between 1961 and 2007. Due to their altitude, massiveness, and position, Romanian Carpathians are an important barrier for different types of air masses between Western and Southeastern Europe. The results show that the change in summer temperatures occurred shortly after 1980. The average magnitude of this change is consistent with changes occurring in other parts of Southern Europe in the same time period although the magnitude of changes at individual weather stations may differ substantially. We aided our analysis by a statistical method based on regression models with serially correlated ARMA errors. [ABSTRACT FROM AUTHOR]

Understanding rainfall variability in the arid, rugged landscapes of Iran requires studying the climatology and spatial patterns of daily precipitation. This paper applies geostatistical and other methods to daily precipitation data from 90 stations that are distributed across Iran to calculate daily rainfall concentration and intensity and map their spatial distribution. The results show that daily precipitation tends to be irregular and intense across much of Iran and that a disproportionately large share of the annual rainfall comes from a small number of high intensity to extreme rainfall events. Analysis of daily rainfall concentration confirms that extreme events are widely distributed across the country, with more than 20% of the land area exposed to the risk of extreme rainfall. The areas experiencing the most frequent extreme events are the hot, dry southern coast and the western slopes of the main north–south range, the Zagros Mountains. Even the wettest parts of the country along the Caspian Sea coast derive a significant amount of their rain from high intensity and extreme events. A cross-validation analysis supports the reliability and accuracy of the geostatistical modeling. [ABSTRACT FROM AUTHOR]

Significant changes in the climatic system have been observed, which may be attributed to human-enhanced greenhouse effect. Even stronger changes are projected for the future, impacting in an increasing way on human activity sectors. The present contribution, prepared in the framework of the MICE (Modelling the Impact of Climate Extremes) Project of the European Union, reviews how climate change may impact on winter tourism in the Alpine region, intense precipitation and flood potential in central Europe, forest damage in Scandinavia and beach holidays in the Mediterranean coast. Impacts are likely to be serious and largely adverse. Due to a lack of adequate information and lack of broadly accepted and reliable mathematical models describing the impact of changes in climate extremes on these activity sectors, it has been found useful to use expert judgement based impact assessment. Accordingly, regional mini-workshops were organized serving as platforms for communication between scientists and stakeholders, vehicles for dissemination of the state-of-the-art of the scientific understanding and for learning stakeholders’ view on extreme events, their impacts and the preparedness system. Stakeholders had the opportunity to react to the scientific results and to reflect on their perception of the likely impacts of projected changes in extremes on relevant activity sectors and the potential to adapt and avert adverse consequences. The results reported in this paper present the stakeholders’ suggestions for essential information on different extreme event impacts and their needs from science. [ABSTRACT FROM AUTHOR]

This paper presents an analysis and discussion of some rainfall characteristics of the European continent. Harmonic and Spectral Analysis are applied to monthly and annual precipitation data derived from 50 selected European meteorological stations. The Harmonic Analysis reveals that the sum of the first and second harmonic describes satisfactorily the mean annual precipitation regime, while the time of maximum of the first harmonic coincides with the time of the observed mean annual maximum of precipitation, almost everywhere. Spectral Analysis reveals the existence of QBO and ENSO signals in some different areas of Europe, while the eleven-year cycle of sunspots seem to have no effect on precipitation across the European continent. Climatic noise is also examined. The lowest values of climatic noise are found in the British Islands and in France, whilst relatively high values are found in the cyclogenetic region of the Gulf of Genoa. An increase in climatic noise has been identified over Mediterranean coastal areas during the summer. [ABSTRACT FROM AUTHOR]

Summary This paper explores the possibility of using ring-width measurements derived from string instruments as a potential source of palaeoclimate information. From a data-base of 1800 measured series, we have identified two sub-sets that compare well with living high elevation spruce (Picea abies (L.) Karst) chronologies from the Bavarian Forest and Austrian Alps. The problems of using historical tree-ring data for dendroclimatic purposes are addressed and by combining the living and historic ring-width data from these two regions, a preliminary proxy of past June/July mean temperatures is developed. This proxy summer temperature record shows striking similarities with a tree-ring based temperature reconstruction for the Central Eastern Alps, the CLIMHIST June/July temperature record from Switzerland and glacial records from the Austrian Alps. This explorative study demonstrates that ring-width series from string instruments may allow the identification of generalised source regions of wood used for instrument making and, most importantly, provide a new unique source for palaeoclimate information at a variety of both temporal and spatial scales for high elevations in central Europe. [ABSTRACT FROM AUTHOR]

Summary In this paper several circulation pattern classifications developed for different European regions are compared with respect to their mutual dependence. Circulation pattern (CP) classifications ? both subjective and objective ? for the British Isles, Germany and Greece were considered. Statistical tests were applied in order to investigate the relationships between each pair of CP classifications. It was found that each pair of classifications cannot be considered to be independent. Time dependence in the relationship between CP classifications shows anomalous behavior only when one of the classifications is subjective. This is due to a gradual change in the methodology, and therefore these classifications should be used for climate evolution studies with care. The dependence between each pair of CP classifications was motivation for developing a new CP classification for the whole European continent which is presented. It is shown that for the local precipitation variability almost no information is lost when comparing this new classification with local classifications. [ABSTRACT FROM AUTHOR]