• Energy Research

15 Pag., 3 Tabl., 10 Fig. This work provides a first assessment of the outstanding characteristics of the anomalous precipitation occurrence in the winter of 2010 over the Iberian Peninsula, as well as on the associated atmospheric driving mechanisms. Large areas of Iberia, those located in the western and southern sectors, registered a new historical maximum in winter precipitation values. Simultaneously, the most extreme, negative North Atlantic Oscillation (NAO) index for winter was recorded in 2010. The anomalous pressure gradient in the North Atlantic region steered a large number of low pressure systems via an unusually southern path, directly influencing Iberia and northern Africa. Storms were frequent, and a high number of days occurred with weather types prone to cause precipitation. In addition, the most extreme daily precipitation episodes were recorded during the period with the strongest negative NAO index. Global climate models for the entire 21st century show that strong negative NAO winters, similar to that which occurred in 2010, may be expected in the future. This work was supported by the research projects CGL2008-01189/BTE and CGL2006-11619/ HID, financed by the Spanish Commission of Science and Technology and FEDER; by EUROGEOSS (FP7-ENV-2008-1- 226487) and ACQWA (FP7-ENV-2007-1-212250), financed by the VII Framework Programme of the European Commission; and ‘La nieve en el Pirineo aragonés: distribución espacial y su respuesta a las condiciones climáticas’, financed by ‘Obra Social La Caixa’ and the Aragón Government. Ricardo Trigo’s work was partially supported by the FCT (Portugal) through project ENAC (PTDC/AAC-CLI/103567/2008). Peer reviewed

42 Pag., 13 Fig. The definitive version is available at: http://www.agu.org/journals/jd/ In this study we analyzed the influence of the El Niño‐Southern Oscillation (ENSO) phenomenon on drought severity at the global scale. A unique aspect of the analysis is that the ENSO influence was quantified using a multiscalar drought indicator, which allowed assessment of the role of the ENSO phases on drought types affecting various hydrological, agricultural and environmental systems. The study was based on ENSO composites corresponding to El Niño and La Niña phases, which were obtained from the winter El Niño 3.4 index for the period 1901–2006. Drought was identified in a multiscalar way using the Standardized Precipitation Evapotranspiration Index (SPEI) and the global SPEIbase data set. The study revealed the differing impacts of the El Niño and La Niña phases on drought severity, the time scales of droughts, and the period of the year when the ENSO phases explained drought variability worldwide. In large areas of America and eastern Europe the role of ENSO events were evident at the shortest time scales (1–3 months) at the beginning of events, but in areas of South Africa, Australia and Southeast Asia the effects were more obvious some months later, and at longer time scales. We also identified areas where severe drought conditions are associated with more than 70% of ENSO events. The persistence of the drought signal at longer time‐scales (e.g., 6‐ or 12‐months) is not directly determined by the atmospheric circulation response to the SST anomalies, since the SPEI anomalies will be caused by the cumulative dry conditions in some specific months. Knowledge of how these effects differ as a function of the El Niño and La Niña phases, and how they propagate throughout the drought time scales could aid in the prediction of the expected drought severity associated with the ENSO. Lags detected during the study may help forecasting of dry conditions in some regions up to one year before their occurrence. This work has been supported by the research projects CGL2008-01189/BTE and CGL2006-11619/HID financed by the Spanish Commission of Science and Technology and FEDER, EUROGEOSS (FP7-ENV-2008-1-226487) and ACQWA (FP7-ENV-2007-1- 212250) financed by the VII Framework Programme of the European Commission, “Las sequías climáticas en la cuenca del Ebro y su respuesta hidrológica” and “La nieve en el Pirineo aragonés: Distribución espacial y su respuesta a las condiciones climáticas” Financed by “Obra Social La Caixa” and the Aragón Government. Peer reviewed

9 Pags., 6 Figs. The Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the of the work, journal citation and DOI. We use high quality climate data from ground meteorological stations in the Iberian Peninsula (IP) and robust drought indices to confirm that drought severity has increased in the past five decades, as a consequence of greater atmospheric evaporative demand resulting from temperature rise. Increased drought severity is independent of the model used to quantify the reference evapotranspiration. We have also focused on drought impacts to drought-sensitive systems, such as river discharge, by analyzing streamflow data for 287 rivers in the IP, and found that hydrological drought frequency and severity have also increased in the past five decades in natural, regulated and highly regulated basins. Recent positive trend in the atmospheric water demand has had a direct influence on the temporal evolution of streamflows, clearly identified during the warm season, in which higher evapotranspiration rates are recorded. This pattern of increase in evaporative demand and greater drought severity is probably applicable to other semiarid regions of the world, including other Mediterranean areas, the Sahel, southern Australia and South Africa, and can be expected to increasingly compromise water supplies and cause political, social and economic tensions among regions in the near future. This work has been supported by research projects CGL2011-27574-CO2-02, CGL2011-27536 and CGL2011–24185 financed by the Spanish Commission of Science and Technology and FEDER, 'Demonstration and validation of innovative methodology for regional climate change adaptation in the Mediterranean area (LIFE MEDACC)' financed by the LIFE programme of the European Commission, CTTP1/12, financed by the Comunidad de Trabajo de los Pirineos, and QSECA (PTDC/AAG-GLO/4155/2012) funded by the Portuguese Foundation for Science and Technology (FCT). ASL was supported by a postdoctoral fellowship from the Catalan Government (2011 BP-B 00078) and CAM was supported by a Juan de la Cierva fellowship by the Spanish Government. Peer reviewed

30 Pags., 2 Tabls., 10 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/09218181 The study examines climate change scenarios of precipitation extremes over the western, central and part of the eastern Mediterranean region for the late 21st century (2070–99) in an ensemble of high-resolution regional climate model (RCM) simulations from the ENSEMBLES project. Precipitation extremes are considered at a wide range of time scales from hourly to multi-day amounts and in individual seasons (DJF, MAM, JJA, SON). We focus on (1) the dependence of the results on the time scale of precipitation aggregation, (2) seasonal differences, (3) uncertainties of the scenarios related to differences amongst the RCM simulations, and (iv) identification of regions and seasons in which the projected changes in precipitation extremes are particularly large and/or robust in the RCM ensemble. The examined ensemble of RCM simulations captures basic precipitation patterns for the recent climate (1961–90), including seasonal changes. Climate change scenarios for the late 21st century differ substantially for short-term (hourly) and multi-day (5-day and 15-day) precipitation extremes, mainly in the western Mediterranean. Projected increases in short-term extremes exceed those of daily and multi-day extremes, and occur even in regions and seasons in which mean precipitation is projected to decline. This change in the patterns of extreme precipitation may have important hydrological consequences, with increases in the severity of flash floods in a warmer climate in spite of the overall drying projected for the region. However, uncertainty of the scenarios of precipitation extremes related to within-ensemble variability is large. Consistency of the projected changes amongst the RCMs is highest in winter and lowest in summer, and generally it is higher for short-term than multi-day extremes. The study was supported by the Czech Science Foundation under project P209/10/2265 and by CGL2011–24185 financed by the Spanish Commission of Science and Technology (CICYT) and FEDER. Parts of the work were carried out during the stay of the first author at Estación Experimental de Aula Dei, Zaragoza, Spain, funded by Consejo Superior de Investigaciones Científicas (CSIC) and the Czech Science Foundation. The research team benefited also through interactions and support within the KLIMATEXT project (CZ.1.07/2.3.00/20.0086) funded by the European Social Fund, and Grupo de Excelencia E68 financed by the Aragón Government and FEDER. The RCM and E-OBS data were produced by the EU-FP6 project ENSEMBLES (contract number 505539). Peer reviewed

5 Pags. Climate change is influencing future precipitation patterns. Especially the short intense rainfalls are expected to increase. Intense precipitation is regarded as one of the main landslide triggering factors. In order to investigate the likely impacts of precipitation change on spatial and temporal patterns of landslide susceptibility it is important to distinguish which type of rainfall has a major influence. Therefore, this study analyses the influence of precipitation maxima and antecedent rainfall conditions on landslide susceptibility. Other dynamic factors such as land cover change are excluded from the analysis. Logistic regression was applied to derive landslide susceptibility maps based on different climate change scenarios. Independent variables were several precipitation indices, current land cover maps and DTM derivatives (e.g. the slope gradient, aspect and curvature). The dependent variable was an inventory of shallow landslides for the period 1962–2007. The extrapolation of landslide susceptibility to the future was performed by applying the coefficients determined from past precipitation indices to those computed from future climate scenarios. The assumption herein is that conditions of the future that are similar to the past result in the same consequences. The study area Waidhofen/Ybbs is located in the alpine foreland in the province of Lower Austria. The predominant lithology is composed of calcareous rocks and Flysch. The land cover is mainly grassland and forest. The results show distinct changes in landslide susceptibility for some regions of the study area. Altered precipitation patterns intensify landslide susceptibility as well as enlarge susceptible areas. Peer reviewed

AbstractThis paper reports the procedure used in creating a homogeneous database of daily precipitation in northeast Spain. The source database comprised 3106 daily precipitation observatories, with data ranging from 1901 to 2002. Firstly, a reconstruction of the series was performed. Data from adjacent observatories were combined to provide long temporal coverage. Data gaps were filled using values from the nearest neighbour observatories. A distance threshold was set to avoid the introduction of spurious information in the series. Secondly, the reconstructed series were subjected to a quality control process. Empirical percentiles corresponding to each precipitation observation were compared to the percentiles corresponding to the closest neighbour observatory, and a threshold difference was set to identify questionable extremes. After careful inspection of each case, 0.1% of the data was rejected and replaced with information from the nearest neighbour. Thirdly, the homogeneity of the series was checked using the standard normal homogeneity test. This allowed detection of inconsistencies present in the original database or introduced by the reconstruction process. Four parameters were assessed at a monthly level: amount of precipitation, number of rainy days, daily maxima, and number of days above the 99th percentile. A total of 43% of the series had some periods of inhomogeneity and were discarded. The final database comprised 828 series with varying time coverages. The greatest number of stations existed during the 1990s, but more than 300 series contained information from the 1960s, and 34 series contained a complete record since 1920. Comparisons of the spatial variability of several parameters describing the daily precipitation characteristics were made. The results showed that the final database had improved spatial coherence. The process described here is proposed as a model for developing a standard procedure for the construction of databases of daily climate data. Copyright © 2010 Royal Meteorological Society

Apple is widely cultivated in temperate regions. The beneficial properties of apple for preventing several illnesses are widely known. Nevertheless, qualitative variables such as sweetness or sourness may influence consumer satisfaction; they are critical factors for fruit consumption and essential in plant breeding. In the present work, 155 apple accessions were assessed during five consecutive years (2014–2018). Four individual sugars and seven organic acids were analysed by HPLC. A mixed-effects model was fitted with accessions and the years’ climatic features as independent variables. A cluster analysis was applied on the mixed-effects model coefficients. Four groups were considered as optimum. Genetics seemed to have the strongest effect and showed clear differences between accession groups, while climate effects were strong only for certain compounds and had a more horizontal behaviour equally affecting the different accession groups. In fact, non-Spanish cultivars tended to concentrate, while autochthone accessions had a much wider spread. Individual sugars and acids concentrations correlated negatively with precipitation and positively with temperature range and solar radiation in all accession groups. The geographic region where the orchard is grown is thus very important in the resulting metabolites profiles. Moreover, apple genetics would also play a decisive role as highlighted in the cluster analysis.