Exceptional Weather Conditions Research Articles

A novel model to detect abnormal thermal energy consumption in existing buildings with limited metering infrastructure

In EU, excessive energy waste occurs in existing buildings due to multiple reasons, such as inadequate building design, frequent operation of the technical building systems far from the design and reference conditions, lack of proper maintenance, lack of building automation and control systems, unexpected or exceptional weather conditions and inappropriate end-user behaviours. In this context, the detection of “abnormal” energy consumption is crucial both to increase end-users’ awareness and to help energy managers and technicians in the energy diagnosis. In this paper, the authors present a novel model to detect abnormal thermal energy consumption in existing buildings equipped with limited metering infrastructure. Four heating seasons of daily thermal energy consumption and indoor environmental data of a case study building located in Central Italy were analysed to develop, train and test the model for data processing, benchmarking, abnormal energy consumption identification and diagnosis. The results of the test phase show the ability of the model to detect behavioural faults, such as the low consumption and indoor air temperature in two dwellings and the high ones in one other. Also, the poor thermal insulation properties of the building were clearly highlighted by the proposed model.

Machine learning based on functional principal component analysis to quantify the effects of the main drivers of wheat yields

Assessing the response of crop yield to year-to-year climate variability at the field scale is often done using process-based models and regression techniques. Although powerful, these tools rely on strong assumptions and can lead to substantial prediction errors. In this study, we investigate the use of a flexible machine learning algorithm combining Functional Principal Component Analysis and Random Forest, to relate field scale wheat yield to local daily climate variables. Instead of computing seasonal, monthly or any other arbitrary time-frame climate averages, climate time series are decomposed by Functional Principal Component Analysis into a few data-driven basis functions, called Principal Curves, in order to summarize the dynamic of key climate variables by a limited number of interpretable components. Scores associated to these components are then used as inputs of a Random Forest algorithm for yield prediction and for analysing important factors responsible for yield variability. To evaluate our approach, we use a French national database including wheat yield data as well as climate and management practice data for 298 farm fields from 2011 to 2016 in four main producing regions. Depending on the regions, our approach can explain from 62 % to 81 % of the yield variability when both agronomic and climate variables are included, down to 56–81 % when ignoring agronomic variables and 51–74 % when ignoring climate variables. Based on a year-by-year cross-validation, RMSE ranges from 0.5 t ha−1 to 2.1 t ha−1 in non-extreme years (2012–2015). However, prediction error can reach 3.6 t ha−1 in case of exceptional weather conditions, such as those experienced in 2016 in Northern France. We find that this new approach performs in most cases better than the same machine learning algorithm using the usual time averages of climate variables, without the need to choose an arbitrary time-frame. We then show how important patterns in weather time series can be identified and how their effects on yield can be interpreted using the proposed modelling framework.

Fungi associated with woody tissues of Acer pseudoplatanus in forest stands with different health status concerning sooty bark disease (Cryptostroma corticale)

From 2018 to 2020, Germany experienced periods of exceptional weather conditions. Extremely high summer temperatures and precipitation deficits induced stress and mortality in forest trees. Acer pseudoplatanus (sycamore) was one of the affected tree species. Symptoms of sooty bark disease (SBD) and severe damage of entire stands, both caused by the fungal species Cryptostroma corticale, were reported more frequently. To explore the non-symptomatic distribution of C. corticale, wood cores from visibly healthy sycamore stems were sampled and all outgrowing fungi were identified and recorded. In total, 50 trees, aged 30–65 years, were sampled at five different forest stands, from which 91 endophytic filamentous morphotypes could be isolated. The fungal endophytic community in the woody tissue of the sycamore trees varied greatly at the different sites and between the trees. The number of isolated morphotypes at the different sites ranged from 13 to 44 and no morphotype was found at all sites. At 1.20-m stem height, 3.3 fungi could be isolated from woody tissue per tree on average. The most abundant species isolated from visibly healthy sycamore in regard to both occurrence at the studied sites and continuity was C. corticale. It was recorded at four of the studied forest stands, from 26% of all studied sycamore trees, and had a frequency of 7.85% relative to the 293 isolated filamentous strains that were isolated. The second most abundant species was Xylaria longipes followed by Lopadostoma turgidum. In this study clear evidence for the endophytic lifestyle of C. corticale is presented which thus appears to be spread further than expected based on visible SBD symptoms.

Analysis of the Degree of Threat to Railway Infrastructure by Falling Tree Vegetation

The article presents a method for determining and evaluating the threat to railway infrastructure from falling trees. The main objective was to identify the degree of threat according to three parameters: the height of tree stands, species composition, and vegetation health. Identification of the threat to individual railway sections would allow the creation of measures that could increase operational safety. Evaluation should be carried out at regular intervals to assess vegetation health during certain seasons. We, therefore, recommend the use of satellite images to provide a data source and regular data updates. The potential benefit is a reduction in railway infrastructure damage and an increase in traffic flow, especially during periods of exceptional weather conditions involving high wind, ice or heavy snow. The new method presented in the paper, based on data for railway infrastructure, law and other data sources in the Czech Republic, determines a Vegetation Threat Index for Railways (VTIR). We selected the Liberec Region as an example case study because of its large spread of wooded areas around railway lines and high incidence of railway traffic accidents.

Analyzing Profitability and Discount Rates for Solar PV Plants. A Spanish Case

The widespread use of renewable energy sources and the growing concern about climate change, together with Spain’s exceptional weather and solar radiation conditions, have led to an increase in the use of photovoltaics for energy production in the country. Solar power generation has been tightly regulated, although the legal framework has changed frequently over the years. When assessing the potential financial performance of any business venture, legal as well as financial aspects must be considered, but a critical factor is the discount rate used, which must reflect the company’s capital cost. Other factors are the period of interest, the firm’s activity, market risk, and the level of debt of firms in the sector. The main objective of this study is thus to estimate the discount rate for companies using photovoltaics to produce solar power. We calculate it by employing two financial techniques: capital asset pricing model and historical return analysis. We then evaluate the investment in a photovoltaic plant with a capacity of 5000 kW located in eastern Spain, assuming it started its activity in different years which coincide with changes in the regulatory framework. The results show the relevance of the initial outlay costs for the profitability of photovoltaic power plants.

The changing seasons

Briony Witherow MSc RNutr. Practical Equine Nutrition, looks at recent exceptional weather conditions and the possible impact on horses when transitioning from winter to spring

Study on Flood Risk Characteristics and Disaster Prevention Countermeasures in the Taihu Basin

The Yangtze River Delta is the region with the strongest comprehensive strength in China. Taihu Basin is the economic core region in the Yangtze River Delta, and it plays a significant role in the economic development of the Yangtze River Delta, as well as in China. The basin is characterized by rapid urbanization, exploitation of natural resources and environmental pollution. After several decades of governance, the flood control system in the Taihu Basin has been significantly improved. Owing to exceptional weather conditions, geographical location and topographical features; the basin is extremely vulnerable to flood hazard. It presents a significant challenge for flood risk management when combined with global developments such as sea level rise. A comprehensive overview of flood management systems and considerations are of great value. In this paper, the characteristics of flood risk are summarized after the basin experienced dramatic development of urbanization over the last twenty years, and the existing problems and potential threats to the basin flood control system are analyzed. In view of a strategic perspective of disaster prevention, this paper presents various countermeasures to deal with the challenging situation in the Taihu Basin, including the structural systems and non-structural measures.

Data-Driven Schemes for Robust Fault Detection of Air Data System Sensors

Failures of the air data system due to exceptional weather conditions have shown to be among the leading causes of aviation accidents. In this respect, most of aircraft Pitot tube failure detection schemes rely on mathematical models and simplified assumptions on the uncertain parameters and disturbances. These methods typically require “ ad hoc ” time-consuming tuning procedures that may produce unreliable performance when validated with actual flight data. In this paper, a complete semiautomated data-driven approach is introduced to select the model regressors, to identify NARX input–output prediction models, to set up robust fault detection filters and to compute fault detection thresholds. To cope with time-dependent and flight-dependent levels of uncertainties online model adaption mechanisms are introduced to limit the critical problem of minimizing the false alarm rate. Extensive validation tests have been conducted using actual flight data of a P92 Tecnam aircraft through the introduction of artificially injected hard and soft failure of the Pitot tube sensor. The approach showed to be remarkably robust in terms of false alarms while maintaining fault detectability to faults of amplitudes less than 1 m/s.

First Results of an ALMA Band 10 Spectral Line Survey of NGC 6334I: Detections of Glycolaldehyde (HC(O)CH2OH) and a New Compact Bipolar Outflow in HDO and CS

Abstract We present the first results of a pilot program to conduct an Atacama Large Millimeter Array (ALMA) band 10 spectral line survey of the high-mass star-forming region NGC 6334I. The observations were taken in exceptional weather conditions (0.19 mm precipitable water) with typical system temperatures T sys < 950 K at ∼890 GHz. A bright, bipolar north–south outflow is seen in HDO and CS emission, driven by the embedded massive protostar MM1B. This has allowed, for the first time, a direct comparison of the thermal water in this outflow to the location of water maser emission from prior 22 GHz Very Large Array observations. The maser locations are shown to correspond to the sites along the outflow cavity walls, where high-velocity gas impacts the surrounding material. We also compare our new observations to prior Herschel Heterodyne Instrument for the Far-infrared (HIFI) spectral line survey data of this field, detecting an order of magnitude more spectral lines (695 versus 65) in the Atacama Large Millimeter/submillimeter Array (ALMA) data. We focus on the strong detections of the complex organic molecule glycolaldehyde (HC(O)CH2OH) in the ALMA data that is not detected in the heavily beam-diluted HIFI spectra. Finally, we stress the need for dedicated THz laboratory spectroscopy to support and exploit future high-frequency molecular line observations with ALMA.

Study of the exceptional meteorological conditions, trace gases and particulate matter measured during the 2017 forest fire in Doñana Natural Park, Spain

In late June 2017, a forest fire occurred in Doñana Natural Park, which is located in southwestern Europe. Many animal and plant species, some of which are threatened, suffered from the impact of this fire, and important ecosystems in the European Union were seriously affected. This forest fire occurred under exceptional weather conditions. The meteorological situation was studied at both the synoptic scale and the local scale using meteorological fields in the ERA-Interim global model from ECMWF (European Centre for Medium Range Weather Forecasts), the WRF (Weather Research and Forecasting) mesoscale model and ground observations collected at El Arenosillo observatory. Anomalies were obtained using records (observations and simulations) over the last two decades (1996–2016). An anticyclonic system dominated the synoptic meteorological conditions, but a strong pressure gradient was present; positive high pressure anomalies and negative low pressure anomalies resulted in intense NW flows. At the surface, wind gusts of 80 km h−1, temperatures up to 35 °C and relative humidity values <20% were observed. In terms of anomalies, these observations corresponded to positive temperature anomalies (differences of 12 °C), positive wind speed anomalies (>29 km h−1) and negative relative humidity anomalies (differences of 40%). The forest fire reached El Arenosillo observatory approximately 8 h after it began. When the fire started, record-setting maximum values were measured for all gases monitored at this site (specifically, peaks of 99,995 μg m−3 for CO, 951 μg m−3 for O3, 478 μg m−3 for NO2, 116 μg m−3 for SO2 and 1000 μg m−3 for PM10). According to the temporal evolution patterns of these species, the atmosphere over a burnt area can recover to initial atmospheric levels between 48 and 96 h after an event. The impact of the Doñana plume was studied using hourly forward trajectories computed with the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model to analyse the emission source for the burnt area. The Doñana fire plume affected large metropolitan areas near the Mediterranean coast. Air quality stations located in the cities of Seville and Cadiz registered the arrival of the plume based on increases in CO and PM10. Using CO as a tracer, measurements from the AIRS and MOPITT instruments allowed us to observe the transport of the Doñana plume from the Strait of Gibraltar to the Mediterranean. Finally, after two days, the Doñana forest fire plume reached the western Mediterranean basin.

The Great Famine in the county of Flanders (1315–17): the complex interaction between weather, warfare, and property rights

AbstractThe exceptional weather conditions and associated harvest failures of 1315–17 marked the beginning of the worst subsistence crisis in European history. Until now, historians have mainly viewed the Great Famine, and medieval famines in general, through theoretical models of the larger fourteenth‐century crisis. However, this article suggests that this approach is flawed and instead applies recent theories on contemporary famines to the crisis of 1315–17 in the county of Flanders. This new perspective not only leads to a re‐examination of existing explanations, such as the role of warfare, but also reveals the importance of property rights in entitlement to food: the power of elites, the relative number of large‐scale landowners, and the structure of household income all influenced peasants’ degree of vulnerability.

Conjunctive use of surface and ground water using Fuzzy Neural Network and Genetic Algorithm.

Semiarid regions with their exceptional weather conditions, low precipitation, and high evapotranspiration pose a great challenge to water resources managers. One possible way to face this challenge is the conjunctive use of both surface water and groundwater resources in these regions. This paper proposes a conjunctive use model which has been implemented in Najafabad plain in central Iran. The model is one of simulation-optimization in which the simulation portion combines the Fuzzy inference system and Neural Networks (FNN) in order to take the climate conditions and the uncertainty in the relevant data into consideration while the optimization portion consists of a multi-objective Genetic Algorithm (GA). The objectives of the optimization model include not only minimizing water shortages in meeting the irrigation demands by the three irrigation systems operating in the region but also minimizing groundwater drawdown in order to control groundwater extraction in the aquifer. These objectives are subject to constraints on the maximum amount of surface and groundwater allocated to the irrigation zones and the maximum capacity of surface irrigation systems and also maximum and minimum allowable cumulative drawdown in the planning horizon. The results of the proposed FNN-GA model demonstrate the importance of the interactions between surface water and groundwater resources considered in a conjunctive use model for the planning and management of water resources in semiarid regions.

Spring ice formation on goose neck collars: effects on body condition and survival in Greenland white-fronted geese Anser albifrons flavirostris

During sub-zero temperatures and strong winds on 10–11 April 2013, we witnessed ice accumulation on plastic collars of staging Greenland white-fronted geese Anser albifrons flavirostris in Iceland. Ice affected 19 of 77 collared individuals seen, all of which had lost ice by 12 April, despite continuing freezing temperatures. Temperatures exceeded freezing after 14 April; daily observations found no recurrence of ice formation before geese left for Greenland in early May. Abdominal profile scores (a field assessment of accumulated body fat) did not differ significantly between geese with and without ice before departure from Iceland. There was no significant difference in return rates between geese with iced (79 %) or un-iced collars (83 %) reported the following autumn. These first reports of collar icing in over 30 years of the project give cause for concern and vigilance, but we recommend continued use of collars given exceptional weather conditions and lack of effects.

Long‐term metapopulation study of the Glanville fritillary butterfly (Melitaea cinxia): survey methods, data management, and long‐term population trends

Long-term observational studies conducted at large (regional) spatial scales contribute to better understanding of landscape effects on population and evolutionary dynamics, including the conditions that affect long-term viability of species, but large-scale studies are expensive and logistically challenging to keep running for a long time. Here, we describe the long-term metapopulation study of the Glanville fritillary butterfly (Melitaea cinxia) that has been conducted since 1991 in a large network of 4000 habitat patches (dry meadows) within a study area of 50 by 70 km in the Åland Islands in Finland. We explain how the landscape structure has been described, including definition, delimitation, and mapping of the habitat patches; methods of field survey, including the logistics, cost, and reliability of the survey; and data management using the EarthCape biodiversity platform. We describe the long-term metapopulation dynamics of the Glanville fritillary based on the survey. There has been no long-term change in the overall size of the metapopulation, but the level of spatial synchrony and hence the amplitude of fluctuations in year-to-year metapopulation dynamics have increased over the years, possibly due to increasing frequency of exceptional weather conditions. We discuss the added value of large-scale and long-term population studies, but also emphasize the need to integrate more targeted experimental studies in the context of long-term observational studies. For instance, in the case of the Glanville fritillary project, the long-term study has produced an opportunity to sample individuals for experiments from local populations with a known demographic history. These studies have demonstrated striking differences in dispersal rate and other life-history traits of individuals from newly established local populations (the offspring of colonizers) versus individuals from old, established local populations. The long-term observational study has stimulated the development of metapopulation models and provided an opportunity to test model predictions. This combination of empirical studies and modeling has facilitated the study of key phenomena in spatial dynamics, such as extinction threshold and extinction debt.

Impact of 2003 heat waves on aerobiological indices of allergenic herbaceous family pollen season in Tuscany (Italy)

The aim of this study was to assess the current aerobiological situation and to investigate the influence of the hot and dry summer 2003 on pollen season (onset, end and duration of the pollen season, peak pollen day and value, total seasonal amount of pollen grains) of herbaceous family as Poaceae, Urticaceae and Compositeae. Heat wave of 2003 influenced the phenology of the main pollen families in Tuscany: the high temperatures occurred during 2003 affected pollen season of different family with different responses. This study confirms the role that the climate has on the flora species and in particular on herbaceous species phenology and the high variability of the pollination among different places, during extreme events. In general, high spring temperature induces an advance of the flowering period and a release of higher pollen quantity of Urticaceae and Poaceae; however, exceptional weather conditions (i.e., summer 2003) could exert an opposite effect, resulting in an impairment of flowering of Urticaceae during autumn. Compositeae species produced a low amount of pollen in 2003, even if the peak value was higher than the average in some stations.

Cladoceran community responses to biomanipulation and re‐oligotrophication in Lake Vesijärvi, Finland, as inferred from remains in annually laminated sediment

Summary1. We studied the role of zooplankton in biomanipulation and the subsequent recovery phase in the Enonselkä basin of Lake Vesijärvi, using subfossil cladocerans in annually laminated sediment. Measures to restore the Enonselkä basin included reduction in external nutrient loading and mass removal of plankti‐ and benthivorous fish. Water clarity increased and the lake changed from a eutrophic to a mesotrophic state. However, some signs of increased turbidity were observed after 5–10 years of successful recovery.2. Annual laminae in a freeze core sample were identified and sliced, based on the seasonal succession of diatoms. Cladoceran remains and rotifer eggs were counted, and Daphnia ephippia and Eubosmina and Bosmina ephippia and carapaces were measured. Annual changes in pelagic species composition were studied with principal component analysis. Individual species abundance, size measurements and various cladoceran‐based indices or ratios (commonly used to reconstruct changes in trophic state and fish predation) were tested for change between four distinct periods: I (1985–1988) dense fish stocks, poor water quality; II (1989–1992) fish removal; III (1993–1997) low fish density, improved water quality; IV (1998–2002) slightly increased fish density and poorer water quality.3. After the removal of fish, the mean size of Daphnia ephippia and Eubosmina crassicornis ephippia and carapaces increased significantly. In contrast, the percentage of Daphnia did not increase. When based on ephippia, the ratio Daphnia/(Daphnia + E. crassicornis) increased, but the interpretation was obscured by the tolerance of fish predation by small Daphnia and by the fact that bosminids were the preferred food of roach. Moreover, ephippial production by E. crassicornis decreased in recent years.4. The abundance of Diaphanosoma brachyurum and Limnosida frontosa increased significantly after the fish population was reduced, while that of Ceriodaphnia and rotifers decreased.5. The expanding littoral vegetation along with improved water clarity was clearly reflected in the concentration of littoral species in the deep sediment core. The species diversity index for the entire subfossil community also increased.6. The period of faltering recovery was characterised by greater interannual variability and an increased percentage of rotifers. Nevertheless, the mean sizes of Daphnia ephippia and E. crassicornis ephippia and carapaces indicated a low density of fish. The deteriorating water quality was apparently related to multiple stressors in the catchment after rehabilitation, such as intensified lakeshore building, as well as to exceptional weather conditions, challenging the management methods in use.

To what extent has climate change contributed to the recent epidemiology of tick-borne diseases?

There is no doubt that all vector-borne diseases are very sensitive to climatic conditions. Many such diseases have shown marked increases in both distribution and incidence during the past few decades, just as human-induced climate change is thought to have exceeded random fluctuations. This coincidence has led to the general perception that climate change has driven disease emergence, but climate change is the inevitable backdrop for all recent events, without implying causality. Coincidence and causality can be disentangled using tick-borne encephalitis (TBE) as a test case, based on the excellent long-term data for this medically significant European disease system. Detailed analysis of climate records since 1970 has revealed abrupt temperature increases just prior to the dramatic upsurge in TBE incidence in many parts of central and eastern Europe. Furthermore, the seasonal patterns of this temperature change are such as might have favoured the transmission of TBE virus between co-feeding ticks. Nevertheless, the pattern of climate change is too uniform to explain the marked heterogeneity in the timing and degree of TBE upsurge, for example in different counties within each of the Baltic countries. Recent decreases as well as increases in TBE incidence must also be taken into account. Instead of a single cause, a network of interacting factors, acting synergistically but with differential force in space and time, would generate this epidemiological heterogeneity. From analysis of past and present events, it appears that human behavioural factors have played a more significant role than purely biological enzootic factors, although there is an explicit causal linkage from one to the other. This includes a range of abiotic and biotic environmental factors, together with human behaviour determined by socio-economic conditions. Many of the abrupt changes followed from the shift from planned to market economies with the fall of Soviet rule. Comparisons between eight countries have indeed revealed a remarkable correlation between poverty indicators and the relative degree of upsurge in TBE from 1993. Against this background of longer-term shifts in TBE incidence, sudden spikes in incidence appear to be due to exceptional weather conditions affecting people's behaviour, which have a differential impact depending on socio-economic factors. This new perspective may also help explain the epidemiology of Crimean-Congo haemorrhagic fever around the eastern Mediterranean region, including the current exceptional epidemic in Turkey.

An Urban Epidemic of Human Myiasis Caused by Dermatobia hominis in French Guiana

We report the onset of an urban epidemic of human myiasis caused by Dermatobia hominis. To our knowledge, this is the first urban epidemic described for D. hominis. The epidemic was most likely related to exceptional weather conditions and notably high rainfall in January 2000, which may have facilitated the maturation of the pupae.

Developing a fire danger rating system for the United Kingdom

Prescribed burning (muirburn) is used extensively in upland Britain for habitat management for sheep, red deer (Cervus elaphus) and red grouse (Lagopus lagopus scoticus), an upland game bird that lives on heather (Calluna vulgaris) moorland. Although forest fires are unusual, wildfires are common in heathland (dominated by C. vulgaris, sometimes with Ulex gallii, western gorse), in stands of Ulex europaeus (gorse), especially where these are close to urban sites, and in grasslands dominated by Molinea caerulea (purple moor grass). Fire hazard is increasing in many areas for a variety of reasons including a reduction in man-power available for prescribed burning and reduced grazing offtake. Fire risk is also increasing due to recent changes in legislation permitting access to the countryside and an increase in recreational activities. While successfully predicting periods of exceptional fire weather conditions, the Met Office Fire Severity Index does not provide specific predictions of fire behaviour for different vegetation types, nor is it sufficiently sensitive for identifying conditions suitable for prescribed burning. C. vulgaris is a unique fuel forming a dense canopy of fine shoots with a proportion of dead fuel suspended in the canopy. The live fuel can, under certain circumstances, have a very low fuel moisture content (below 45%). This may occur when shoots are damaged by frost and ice or when the ground is cold or frozen and so reducing water uptake by the shoots. In this paper, we discuss the development of a fire danger rating system for the United Kingdom with regard to the unique situation of fuel characteristics, availability of numerical meteorological data, prescribed burning regime and infrastructure.

Ursachen und Verlauf der Buchdrucker-Epidemien (Ips typographus L.) in der Schweiz von 1984 bis 1999 | Causes and progress of the eight-toothed spruce bark beetle epidemics (Ips typographus) in Switzerland from 1984 to 1999

In the past 20 years, several mass attacks by the eight-toothed spruce bark beetle (Ips typographus L.) occurred in Switzerland. Since 1984 data on compulsory fellings, numbers of infestation spots and numbers of beetles captured in pheromone traps have been collected in all Swiss forest districts. The annual data were published in short reports. This paper gives an overview of the progress of bark beetle epidemics from 1984 to 1999. On the national level, two periods with epidemics of the spruce bark beetle can be distinguished. The first epidemic started after windthrows and drought in the years 1982 and 1983. It reached its height in 1984/1985 and faded at the end of the decade. The second epidemic started after the storm Vivian (February 1990). It reached its height in 1992/1993 and ended in 1997. Storm damage that produced high quantities of suitable breeding material was not the only factor for the bark beetle gradation;weather conditions were also exceptional, such as hot and dry vegetation periods. Windthrows and exceptional weather conditions are mostly events on regional scales and do not affect the whole country with the same intensity. The gradation that appears to be an «epidemic of the spruce bark beetle in Switzerland after the storm Vivian» is in truth the accumulation of several local epidemics. This is shown by the number of compulsory fellings and infestation spots analysed at regional levels. Extreme weather conditions and storms not only directly influence the bark beetle population, they also stress standing trees, thus creating suitable breeding material for bark beetles. To analyse the influence of exceptional weather conditions on bark beetle epidemics,it is therefore necessary to evaluate regional data.