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© 2010 Elsevier Inc. The authors thank the NASA TOMS Science Team for the satellite data used in this paper. Manuel Anton thanks the Ministerio de Ciencia e Innovacion and Fondo Social Europeo for the award of a postdoctoral grant (Juan de la Cierva). Author (Pavan S Kulkarni) is thankful to the Geophysics Centre of the University of Evora (CGE-UE) for the fellowship in the project 'SPATRAM-MIGE Polar Project', funded by the Portuguese Science Foundation - FCT. This work was partially supported by Ministerio de Ciencia e Innovacion under project CGL2008-05939-C03-02/CLI and by Fundacao para a Ciencia e a Tecnologia though projects PROPOLAR and PTDC/CTE-ATM/102142/2008., This paper focuses on the spatial-temporal structure of total ozone column (TOC) over Portugal. This relevant region of southwestern Europe has not been evaluated yet in detail due to the lack of continuous and well-covered ground-based TOC measurements. The data used in this study are derived from the NASA's Total Ozone Mapping Spectrometer (TOMS) for the period 1978-2005. The TOC spatial behavior shows no significant longitudinal variability (smaller than 3%). In contrast, the variation in latitude changes between 3.5% and 6% depending on the calendar month. The TOC in the northern Portugal is, on average, higher than that recorded in the South. The temporal variability was analyzed for three scales: long-term, seasonal and short-term. The long-term TOC changes are analyzed between 1978 and 1999 by means of linear least squares fits. The results show an annual TOC trend of (2.65 +/- 0.70)%/decade which is statistically significant at the 95% confidence level. This TOC decrease is smaller than the trends obtained in other midlatitudes regions which could be partially explained by the compensation due to the observed increase in the tropospheric ozone over the Iberian Peninsula. A trend analysis performed for each individual month shows a statistically significant TOC decline between March and October, with a maximum linear trend value of (-7.30 +/- 45)%/decade in May. The amplitude of the seasonal TOC cycle over Portugal shows a slight dependence in latitude, varying from 28.6 DU (37.5 degrees N) to 33.6 DU (41.5 degrees N). Finally, the short-term variability showed a notable seasonal behavior, with maximum day-to-day TOC changes in winter (similar to 6%) and minimum in summer (similar to 3%). In addition, the persistence (characterized by the autocorrelation coefficients) strongly decreases after a few days (except in summer months)., Ministerio de Ciencia e Innovación, Fondo Social Europeo, Geophysics Centre of the University of Evora (CGE-UE), Portuguese Science Foundation - FCT, Fundaçao para a Ciencia e a Tecnologia, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© European Geosciences Union 2002. The authors thank D. A. Wheeler for his extremely helpful review which improved substantially the manuscript and two anonymous reviewers for their comments. The INM for providing the data., Extremely cold days (ECDs), with minimum temperatures lower than -4.6°C, have been analysed for Madrid. This threshold corresponds to the 5th percentile of the period 1963-1999. Adopting a case analysis approach, five synoptic patterns have been identified that produce these extremely low temperatures. Three of them are associated with cold air flows over the Iberian Peninsula, and the other two with a lack of significant circulation over the region. A non-linear association with the North Atlantic Oscillation (NAO) has been identified using log-linear models. The NAO positive phase leads to an increase in the winter frequency of those synoptic patterns associated with stagnant air flow over Iberia, while those characterised by cold, northern flows do not appear to be similarly influenced., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Wiley-Blackwell. All rights reserved. Artículo firmado por 24 autores. We acknowledge the WCRP/CLIVAR Working Group on Seasonal to Interannual Prediction (WGSIP) for establishing the Climate-system Historical Forecast Project (CHFP: Kirtman and Pirani, 2009) and the Centro de Investigaciones del Mar y la Atmósfera (CIMA) for providing the model output. We also thank the data providers for making the model output available through CHFP. We have no potential sources of conflict of interest. The contribution of AYK is funded by the Academy of Finland, project no. 286298., Using an international, multi-model suite of historical forecasts from the World Climate Research Programme (WCRP) Climate-system Historical Forecast Project (CHFP), we compare the seasonal prediction skill in boreal wintertime between models that resolve the stratosphere and its dynamics (high-top') and models that do not (low-top'). We evaluate hindcasts that are initialized in November, and examine the model biases in the stratosphere and how they relate to boreal wintertime (December-March) seasonal forecast skill. We are unable to detect more skill in the high-top ensemble-mean than the low-top ensemble-mean in forecasting the wintertime North Atlantic Oscillation, but model performance varies widely. Increasing the ensemble size clearly increases the skill for a given model. We then examine two major processes involving stratosphere-troposphere interactions (the El Niño/Southern Oscillation (ENSO) and the Quasi-Biennial Oscillation (QBO)) and how they relate to predictive skill on intraseasonal to seasonal time-scales, particularly over the North Atlantic and Eurasia regions. High-top models tend to have a more realistic stratospheric response to El Niño and the QBO compared to low-top models. Enhanced conditional wintertime skill over high latitudes and the North Atlantic region during winters with El Niño conditions suggests a possible role for a stratospheric pathway., Academy of Finland, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2011 American Meteorological Society. We gratefully acknowledge the support of the Climate Program Office at the U.S. National Oceanic and Atmospheric Administration, and the International Geosphere Biosphere, Past Global Changes (PAGES) Program Office in Bern, Switzerland. We are also grateful for the support of the Luso-American Foundation (FLAD), the Portuguese Foundation for Science and Technology, and the Institut Dom Luiz, University of Lisbon for their help in conducting the symposium that set the background for this assessment. Ricardo Trigo and David Barriopedro received support from Portuguese Foundation for Science and Technology (FCT) with project MEDIATIC (PTDC/AAC-CLI/103361/208). We also acknowledge the helpful reviews provided by R. Seager and an anonymous reviewer and thank H. Goosse for kindly making available to us one of the figures., Developing accurate reconstructions of past climate regimes and enhancing our understanding of the causal factors that may have contributed to their occurrence is important for a number of reasons; these include improvements in the attribution of climate change to natural and anthropogenic forcing, gaining a better appreciation for the range and magnitude of low-frequency variability and previous climatic regimes in comparison with the modern instrumental period, and developing greater insights into the relationship between human society and climatic changes. This paper examine up-to-date evidence regarding the characteristics of the climate in medieval times (A.D. 950-1400). Long and high-resolution climate proxy records reported in the scientific literature, which form the basis for the climate reconstructions, have greatly expanded in the last few decades, with greater numbers of sites that now cover more areas of the globe. Some comparisons with the modern climate record and discussion of potential mechanisms associated with the patterns of medieval climate are presented here, but our main goal is to provide the reader with some appreciation of the richness of past natural climate variability in terms of its spatial and temporal characteristics., Climate Program Office at the U.S. National Oceanic and Atmospheric Administration, International Geosphere Biosphere, Past Global Changes (PAGES) Program Office in Bern, Switzerland, Luso-American Foundation (FLAD), Portuguese Foundation for Science and Technology (FCT), Institut Dom Luiz, University of Lisbon, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2008 Royal Meteorological Society. Ricardo Trigo and Ricardo García Herrera received support from the Portuguese-Spanish integrated action (E-27/2005) funded by CRUP and MCYT and the EU 6th Framework Program (CIRCE). José M. Vaquero acknowledges support from the Gulbenkiam Foundation-Biblioteca Nacional de Portugal, and the Programme 'José Castillejo' from the Spanish Science Ministry. Mariano Barriendos acknowledges the Research Programme 'Ramón y Cajal' and Research Group 'Paisatge i paleoambients a la muntanya mediterrania', University of Barcelona. Jurg Luterbacher is supported by the Swiss National Science Foundation through its National Centre of Excellence in Research on Climate (NCCR) and the EU 6th Framework Program (CIRCE). Some of the historical Portuguese material used in this work was consulted at the Biblioteca Nacional de Portugal (Lisbon, Portugal) and Biblioteca del Real Observatorio de la Marina (San Fernando, Spain). Long-term series of observed data were also obtained through the Portuguese project SIGN (Signatures of environmental chance in the observations of the Geophysical Institutes) under POCTI/CTA/47803/2002 project. The authors are indebted to Manola Brunet and Javier Sigro for providing data for Madrid. Finally the authors would like to thank both reviewers for their helpful and constructive comments that help in improving the manuscript., The year 1816 was characterized by unusual weather conditions, in particular, by a cold and wet Summer season ('year without a summer') on both the European and North American continents. The eruption of Tambora, an active stratavolcano, on the Island of Sumbaya (Indonesia) in April 1815 has been identified as the main driving force for the strong 1816 temperature anomaly. This climate anomaly has been relatively well studied in central Europe, France, Scandinavia and the United Kingdom. The unusual unsettled weather and climate at mid-latitudes in 1816 and 1817 had major socioeconomic impacts. particularly in terms of a poor yield of agricultural production, malnutrition and consequentially an increased potential for diseases anti epidemics. The Iberian Peninsula was also affected by the intense climate anomalies during, those years. Documentary Sources describe the impact that the cold and wet summer of 1816 had on agriculture, namely the bad quality of fruits, delayed ripening of vineyards and cereals. It is within this context that we stress the relevance of recently recovered meteorological observed data, from 1816 onwards. for stations located in Portugal (Lisbon) and also for a longer period for the Spanish stations of Madrid, Barcelona and San Fernado-Cadiz. We have compared observed (station-based) and large-scale reconstructed seasonal temperature anomalies computed for the winter and summer seasons after the eruption (1816-1818). There is qualitative agreement between the two independent data sets, though some stations partly indicate stronger departures from the long-term averages for single years compared to neighbouring grid points. In particular. all available stations reveal a cold summer of 1816, mainly in July and August. In comparison to the 1871-1900 reference period, those two months were 2-3 degrees C cooler, close to what has been reported for central Europe. We also discuss the regional climate anomalies for those years (1816-1818) using inde, Unión Europea. FP6, Conselho de Reitores das Universidades Portuguesas (CRUP), Portugal, Ministerio de Ciencia y Tecnología (MCYT), España, Fundação Calouste Gulbenkian (Portugal), Ministerio de Educación y Ciencia (MEC), España, Programa Ramón y Cajal, Grupo de investigación ‘Paisatge i paleoambients a la muntanya mediterr`ania’ (Universidad de Barcelona), National Centre of Excellence in Research on Climate (NCCR), Suiza, Project SIGN (Signatures of environmental change in the observations of the Geophysical Institutes), Portugal, Programa CIRCE (UE), Biblioteca Nacional de Portugal (BNP), Programa José Castillejo (MEC), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2006 American Meteorological Society. The authors thank the ECMWF for providing their reanalysis data. We also thank the Instituto Nacional de Meteorología (INM) for providing the precipitation data for the Spanish stations. We thank the European Climate Assessment (ECA) project (supported by the Network of European Meteorological Services EUMETNET). This work was supported by the Portuguese Science Foundation (FCT) through project VAST (Variability of Atlantic Storms and Their impact on land climate) Contract POCTI/ CTA/46573/2002, cofinanced by the European Union under program FEDER. The Universidad Autónoma de Madrid (UAM) also supported this work. Thanks to Julio Díaz for his help. Finally, the suggestions of two anonymous reviewers helped to improve the original manuscript., March monthly accumulated precipitation in the central and western regions of the Iberian Peninsula presents a clear continuous decline of 50% during the 1960-97 period. A finer analysis using daily data reveals that this trend is exactly confined to the month of March. However, this is merely the most visible aspect of a larger phenomenon over the North Atlantic/European sector. The European precipitation trends in March for the period 1960-2000 show a clear distribution of increasing precipitation in the northern regions (the British Isles and parts of Scandinavia) together with decreasing trends throughout the western Mediterranean Basin. Relevant circulation changes over the North Atlantic and European sectors explain these precipitation trends. First, a regional Eulerian approach by means of a weather-type (WT) classification shows that the major rainfall contributors in March display significantly decreasing frequencies for the Iberian Peninsula, in contrast to the corresponding "wet" weather types for the U.K./Ireland sector, which display increasing frequencies. Within a larger context, a Lagrangian approach, based oil the analysis of storm tracks over Europe and the North Atlantic region, reveals dramatic changes in the location of cyclones in the last four decades that coincide with the corresponding precipitation trends in Europe. The North Atlantic Oscillation is suggested to be the most important large-scale factor controlling both the circulation changes and the precipitation trends over the Euro-Atlantic area in March. Finally, the potential impact of reduced precipitation for rivers and water resources in the Iberian Peninsula is considered., Network of European Meteorological Services EUMETNET, Fundação para a Ciência e a Tecnologia (FCT), Portugal, Program FEDER (UE), Unión Europea (UE), Project VAST (Variability of Atlantic Storms and Their impact on land climate). UE, Universidad Autónoma de Madrid (UAM), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. This research was supported: in Spain by project SPECT (CGL2005-06097/CLI) and the Ramón y Cajal Program of the Ministerio de Educación y Ciencia (MEC) and project PalMA (CCG07-UCM/ESP-3045) by the Comunidad Autónoma de Madrid and the Universidad Complutense de Madrid; in Canada by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS) and the Atlantic Innovation Fund (AIF-ACOACanada); and in Germany by the EU project Millennium European Climate. The authors thank Vladimir Cermak and two anonymous reviewers for their comments and suggestions. Also we appreciate the contributions from Volker Rath and Jason Smerdon, editors of this special volume., Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries. The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change. The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments., SPECT, Programa Ramón y Cajal (Ministerio de Educación y Ciencia, MEC), Comunidad de Madrid, Universidad Complutense de Madrid (UCM), Natural Sciences and Engineering Research Council of Canada (NSERC), Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), Atlantic Innovation Fund (AIF-ACOACanada), Unión Europea (UE), Proyecto PalMA, Project Millennium European Climate (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

©2003 American Meteorological Society. The authors wish to thank C. Appenzeller, E. Cook, J. Luterbacher, C. J. Proctor, and F. S. Rodrigo for providing their proxy NAO reconstructions. This study is supported by the Spanish Comisión Interministerial de Ciencia y Tecnología under Grant CLI98-0649., Records of taxes collected during the seventeenth and eighteenth centuries contribute to understanding of climatic variability of the subtropical North Atlantic region. Historical documentary sources in the Canary Islands have been used to construct cereal production series for the period 1595–1836. The cereal growth period in this region covers essentially the rainy season, making these crops adequate to characterize the annual precipitation. A proxy for the Islands' rainfall based on the historical series of wheat and barley production has been constructed and assessed by using two independent series of dry and wet years. The spectral analysis of the crop production reveals a strong non stationary behavior. This fact, along with the direct comparison with several reconstructed and instrumental North Atlantic Oscillation series, suggests the potential use of the reconstructed precipitation as a proxy for this climatic oscillation during preinstrumental times., Comisión Interministerial de Ciencia y Tecnología (CICYT), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2014 American Geophysical Union. We thank the European Centre for Medium-Range Weather Forecasts and the National Centers for Environmental Prediction for the reanalysis data ERA-Interim and NCEP. We also thank the UK Met Office for the weather charts and the Freie Universität Berlin for the storm names. Iñigo Gómara is supported by Spanish national funds (research project MULCLIVAR CGL2012-38923-C02-01). We thank Sven Ulbrich (University of Cologne) and Marc Stringer (University of Reading) for help with data processing. We are grateful to John Methven, Len Shaffrey (both University of Reading), and David Stephenson (University of Exeter) for discussions and Peter Clark (University of Reading) for providing additional synoptic charts. We also thank Olivia Martius and two anonymous reviewers for their helpful and constructive comments. The ERA-Interim Re-analysis data set is available from European Centre for Medium-Range Weather Forecasts (http://apps.ecmwf.int/datasets/). The NCEP reanalysis data set is available from the National Centers for Environmental Prediction (www.ncep.noaa.gov/). The weather charts are available from the UK Met Office (http://www.metoffice.gov.uk), and the storm names from the Freie Universität Berlin (http://www.met.fu-berlin.de/adopt-avortex/). All other data are available from the authors (j.g.pinto@reading.ac.uk), Some recent winters in Western Europe have been characterized by the occurrence of multiple extratropical cyclones following a similar path. The occurrence of such cyclone clusters leads to large socio-economic impacts due to damaging winds, storm surges, and floods. Recent studies have statistically characterized the clustering of extratropical cyclones over the North Atlantic and Europe and hypothesized potential physical mechanisms responsible for their formation. Here we analyze 4 months characterized by multiple cyclones over Western Europe (February 1990, January 1993, December 1999, and January 2007). The evolution of the eddy driven jet stream, Rossby wave breaking, and upstream/downstream cyclone development are investigated to infer the role of the large-scale flow and to determine if clustered cyclones are related to each other. Results suggest that optimal conditions for the occurrence of cyclone clusters are provided by a recurrent extension of an intensified eddy driven jet toward Western Europe lasting at least 1 week. Multiple Rossby wave-breaking occurrences on both the poleward and equatorward flanks of the jet contribute to the development of these anomalous large-scale conditions. The analysis of the daily weather charts reveals that upstream cyclone development (secondary cyclogenesis, where new cyclones are generated on the trailing fronts of mature cyclones) is strongly related to cyclone clustering, with multiple cyclones developing on a single jet streak. The present analysis permits a deeper understanding of the physical reasons leading to the occurrence of cyclone families over the North Atlantic, enabling a better estimation of the associated cumulative risk over Europe., Spanish national funds, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 American Meteorological Society. This work was partially supported by the Spanish Ministry of Science through Grant HP 2004-0039. We also thank the Instituto Nacional de Meteorología (INM) for providing the precipitation data for the Spanish stations. R. M. Trigo was supported by Projects VAST (Variability of Atlantic Storms and their impact on land climate), Contract POCTI/CTA/ 46573/2002, and CLIMAAT (Climate and Meteorology of the Atlantic Archipelagos), Interreg IIIb A3/2.3, both cofinanced by the EU under program FEDER. Three anonymous reviewers also helped to improve this manuscript., The 2004/05 hydrological year (October 2004 to September 2005) was characterized by intense dry conditions affecting most of western Europe (35 degrees-55 degrees N and 10 degrees W-10 degrees E). In Iberia the drought affected every month of this period, with the southern half of Iberia receiving roughly 40% of the usual precipitation by June 2005. Moreover, this episode stands as the driest event in the last 140 yr, producing major socioeconomic impacts particularly due to the large decrease in hydroelectricity and agricultural production in both Iberian countries (Portugal and Spain). To assess the atmospheric submonthly circulation associated with this drought an Eulerian [weather types (WTs)] and a Lagrangean (objective storm tracks) analysis were combined. There was a dramatic drop in "wet" WT frequency during winter, with less than 50% of the normal value, and a corresponding increase of "dry" WTs. The storm-track analysis reveals an impressive northward displacement of cyclone trajectories in the North Atlantic sector in winter months, resulting in an almost complete absence of cyclones crossing Iberia and western Europe. At the monthly scale, the intense drought in Iberia was due to a combination of different physical mechanisms. First, the scarce precipitation observed between November 2004 and January 2005 was associated with positive North Atlantic Oscillation (NAO) indexes for these months. In February, the East Atlantic (EA) pattern seems to be the main driver. In March neither the negative NAO (-1.8) nor the positive EA (1.1) are capable of explaining the large negative precipitation anomalies. However, it is shown that during March 2005, an intense and anomalous blocking was displaced southward of its usual location, inhibiting the occurrence of precipitation over Iberia and leading to a negative NAO index anomalously associated with low precipitation records., Spanish Ministry of Science, EU, program FEDER., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 by the American Geophysical Union. This work was supported by UNICAJA. The authors wish to thank M. J. Puertas for abstraction of the original reports; A. Gullón for helping in the historical interpretation; M. Barriendos, P. Jones, G. Können and D. Wheeler for the fruitful discussion about the interpretation of the results; the Spanish Meteorological Institute; and C. Camacho for useful information about the characteristics of the Tavira tower. Finally, the two anonymous reviewers are thanked for their helpful comments., A new documentary source of data for wind, atmospheric pressure and air temperature for the city of Cadiz (southern Spain) has been abstracted, analyzed and compared with present-day data. Wind records cover the period 1806-1852 with three observations per day. Instrumental pressure and temperature cover the period 1825-1852. While the historical pressure series shows average values very close to that found for the period 1971-2000, temperature shows a large asymmetric seasonal warming, with increments in the order of 2 degrees C for the winter months and almost no change for summer. Wind measurements have been transformed into their numerical equivalents and then compared with present-day values. The analysis shows that the numerical estimation of ancient wind forces observed at Cadiz, while providing a robust climatic signal, has a strong bias to larger values than their instrumental equivalents. Despite the uncertainties involved in the interpretation of early wind series, this effect could be related to the recording of "average wind gusts" rather than average winds as measured by today's anemometers. In consequence, wind climatologies based on historical data, which recently are becoming available to the scientific community, should be used carefully., UNICAJA, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2001 American Meteorological Society. This work was supported by Project Number CLI97-0558, Comunidad de Madrid, and Fundación Ramón Areces. The authors also thank P. Brandt, P. Cuesta, M. Widmann, and E. Zorita for their comments on the original version of the manuscript. We thank also F. Zwiers and the two anonymous reviewers for their valuable comments and suggestions., A quality control process involving outliers processing, homogenization, and interpolation has been applied to 95 monthly precipitation series in the Iberian Peninsula, southern France, and northern Africa during the period 1899- 1989. A detailed description of the procedure results is provided and the impact of adjustments on trend estimation is discussed. Outliers have been censored by trimming extreme values. Homogeneity adjustments have been developed by applying the Standard Normal Homogeneity Test in combination with an objective methodology to select reference series. The spatial distribution of outliers indicates that they are due to climate variability rather than measurement errors. After carrying out the homogeneity procedure, 40% of the series were found to be homogeneous, 49.5% became homogeneous after one adjustment, and 9.5% after two adjustments. About 30% of the inhomogeneities could be traced to information in the scarce history files. It is shown that these data present severe homogeneity problems and that applying outliers and homogeneity adjustments greatly changes the patterns of trends for this area., Comunidad de Madrid, Fundación Ramón Areces, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License. This work has been possible thanks to the funding by the MCINN projects CGL2005-06097 and CGL2008-06558-C02-C01/CLI, and the MARM project 200800050084028. The manuscript was significantly improved thanks to helpful and insightful comments of four anonymous reviewers. We are grateful to A. Grinsted and S. Jevrejeva for making the MatLab wavelet coherence package and their global sea level reconstructions available, and to A. Kemp for kindly sharing the data from North Carolina with us. We would also like to thank G. Sgubin for interesting discussions and to I. Fast for providing us with the extended FOR1 data.The publication of this article is financed by CNRS-INSU., Studies addressing climate variability during the last millennium generally focus on variables with a direct influence on climate variability, like the fast thermal response to varying radiative forcing, or the large-scale changes in atmospheric dynamics (e. g. North Atlantic Oscillation). The ocean responds to these variations by slowly integrating in depth the upper heat flux changes, thus producing a delayed influence on ocean heat content (OHC) that can later impact low frequency SST (sea surface temperature) variability through reemergence processes. In this study, both the externally and internally driven variations of the OHC during the last millennium are investigated using a set of fully coupled simulations with the ECHO-G (coupled climate model ECHAMA4 and ocean model HOPE-G) atmosphere-ocean general circulation model (AOGCM). When compared to observations for the last 55 yr, the model tends to overestimate the global trends and underestimate the decadal OHC variability. Extending the analysis back to the last one thousand years, the main impact of the radiative forcing is an OHC increase at high latitudes, explained to some extent by a reduction in cloud cover and the subsequent increase of short-wave radiation at the surface. This OHC response is dominated by the effect of volcanism in the preindustrial era, and by the fast increase of GHGs during the last 150 yr. Likewise, salient impacts from internal climate variability are observed at regional scales. For instance, upper temperature in the equatorial Pacific is controlled by ENSO (El Nino Southern Oscillation) variability from interannual to multidecadal timescales. Also, both the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO) modulate intermittently the interdecadal OHC variability in the North Pacific and Mid Atlantic, respectively. The NAO, through its influence on North Atlantic surface heat fluxes and convection, also plays an important role on the OHC at multi, Ministerio de Ciencia e Innovación (MCINN), España, Ministerio de Medio Ambiente, Medio Rural y Marino (MARM), España, Centre national de la recherche scientifique CNRS-INSU, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2011. CC Attribution 3.0 License. This work has been partially supported by the research projects CGL2007-61328/CLI, CGL2009-07950, UE SafeWind Grant Agreement No. 213740 and VA025A10-2. Two anonymous reviewers provided helpful comments and suggestions. The authors wish to thank the following institutions which provided us with data: ERA40 from the European Center for Weather Medium Forecast (ECWMF), the Iberian Wind Dataset from the Spanish Meteorological Service (AEMET: Agencia Estatal de Meteorologia, Spain) and the teleconnection indices by the US Climate Prediction Center from the web site http://www.cpc.noaa.gov/data/teledoc/telecontents.shtml., This paper investigates, by means of Singular Value Decomposition analysis, the springtime relationships between the mean sea-level pressure field over the North Atlantic and the regional wind gusts over the Iberian Peninsula, identifying the main atmospheric circulation patterns linked to gust wind speed anomaly configurations. The statistical significance of the obtained modes is investigated by means of Monte Carlo approach. The analysis highlighted that the covariability is dominated by two main large-scale features of the atmospheric circulation over the North Atlantic. The first mode relates to Iberian gust wind speeds to the Scandinavian pattern (SCAND), linking the large-scale pattern to above-normal wind gusts. The second covariability mode, associated with the North Atlantic Oscillation (NAO) pattern, correlates with maximum wind speeds over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind gust correlations over northern (southern) Iberia. To find true relationships between large-scale atmospheric field and the gust wind speeds, composite maps were built up to give an average atmospheric circulation associated with coherent wind gust variability over Iberia., SafeWind Project, Unión Europea (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© John WiIley & Sons LTD. This work was supported by the research framework established between STREAM group at University Complutense of Madrid and Iberdrola Renovables Energia S.A., through a fellowship programme under Art. 83 of L.O.U. Two anonymous reviewers contributed to improve the original manuscript., The study of the wind power output variability comprises different time scales. Among these, low-frequency variations can substantially modify the performance of a wind power plant during its lifetime. In recent years, other temporal scales such as the short-term variability or the climatological conditions of wind and the corresponding generated power have been investigated in depth. However, the study of longer decadal and multidecadal variations is still in its early stages. In this work, the wind power output long-term variability is analysed for two locations in Spain, during the period 1871-2009. This is attained by computing the annual wind speed probability density functions derived from an ensemble of atmospheric sea level pressure data set through a statistical downscaling based in evolutionary algorithms. Results reveal significant trends and periodicities in multidecadal bands including 13, 25 and 46years, as well as significant differences among both sites. The impact of the leading large-scale circulation patterns (NAO, EA, SCAND and AMO) on wind power output and its stationarity is analysed. Results on both locations show non-stationary significant and opposite seasonal couplings with these forcings. Finally, the long-term variability of the reconstructed Weibull parameters of the annual wind speed distributions is used to derive a linear model to estimate the annual wind power., STREAM Group (University Complutense of Madrid - UCM), Iberdrola Renovables Energia S.A., Universidad Complutense de Madrid (UCM), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 Royal Meteorological Society. This study is supported by the Spanish Comision Interministerial de Ciencia y Tecnologia under grant CLI98-0649. The Spanish Instituto Nacional de Meteorología provided the data for this study. The authors wish to thank the two anonymous referees for their useful comments, which contributed to improving the quality and presentation of this work., A strong decreasing trend in the Canary Islands' precipitation is detected by studying daily rainfall time series for the second half of the 20th century. An analysis of the extreme events shows that this trend is due mainly to a decrease in the upper percentiles of the precipitation distribution. The results suggest that local factors play a fundamental role on extreme event behaviour., Spanish Comisión Interministerial de Ciencia y Tecnología, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2004 StudiaGeo s.r.o., Equivalent temperature based in the NCEP/NCAR reanalysis database has been used as a simultaneous measure of temperature and humidity. Its variations during the 1958-1998 added to the effect of the inclusion of satellite data during the late seventies have been analyzed. An increase of the globally averaged equivalent temperature has been detected, the trend has been considerably greater during the first half of the study period and significant differences can be found between continental and oceanic areas. The relation of the trend with four of the main modes of climate variability has been assessed. The North Atlantic Oscillation and the Artic Oscillations are closely related to the equivalent temperature over the North Atlantic basin, extending toward Northern Asia in the second case. El Nino/Southern Oscillation and the Antarctic Oscillation seem to have a more global effect., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Springer-Verlag 2006. This work was supported by the Spanish Ministry of Science and Technology (MCYT) under Grant REN2002-04558-C04- 01=02=03=04 and by the Galician Programme of Research and Development under Grant GIDIT03PXIC38301PN. This work was supported also by a postdoctoral fee (SFRH= BPD=22178=2005) to the principal author from the FCT of Portuguese Ministry of Science, Technology and Education. The authors wish to thank the Spanish National Meteorology Institute (INM) for providing the data analysed in this study., The Iberian Peninsula is one of the regions in the world with higher occurrence of cut-off low systems (COL). The aim of this paper is to analyse the weather events (rainfall and cloudiness layer) associated to COLs in the Iberian Peninsula with tools not previously used: (a) the use of the new multidecadal COLs database developed by Nieto et al (2005) that permit us to study a 41 years period (1958-1998), (b) the checking of the expected weather events (rainfall and cloudiness layer) associated with COLs in a conceptual model (Winkler et al, 2005) and (c) the extensive use of radiosoundings to analyse convective instability in areas inside and close to the COL. Two points of view are used to make the analysis: (1) a source oriented method, when a particular COL is followed and its associated precipitation and cloudiness is analysed over four quadrants in which Iberia was divided and (2) a receptor oriented method, when the precipitation associated to COLs is analysed in given areas, defined by patterns of precipitation. Results reveal that the precipitation and cloudiness patterns associated to COLs in the conceptual model reproduce quite well the main characteristics found over the Iberian Peninsula. The generalized idea that most of the COLs produce intense convective rainfall is show to be misleading. Convective phenomena are important usually when the centre of the COL is located on the Mediterranean region. Most of the rainfall associated with COLs comes from the baroclinic shield; specially in cases located over the west half of the Iberian Peninsula. It is shown that nearly 30% of COLs do not induce any rainfall; most of them located in the southern half of the Peninsula, and mainly during autumn. Only 30% of COLs produce generalized rainfall over the whole analysed territory, being most of them (about 90%) located over the western half of the Iberian Peninsula., Spanish Ministry of Science and Technology (MCYT), Galician Programme of Research and Development, FCT of Portuguese Ministry of Science, Technology and Education, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

The Mediterranean region is expected to be highly impacted by global warming, although the uncertainty of future scenarios, particularly about precipitation patterns remains quite large. To better predict shifts in its current climate system and to test models, more regional climate records are needed spanning longer than the instrumental period. Here we provide a high-resolution reconstruction of Autumn precipitation for the Central Pyrenees since 1500 CE based on calcite sublayer width from from Montcortès Lake (Central southern Pyrenees) varved sediments. The 500-yr calcite data series was detrended and calibrated with instrumental climate records by applying correlations and cross-correlations to regional precipitation anomalies. Highest relationships were obtained between a composite calcite series and autumn precipitation anomalies for the complete calibration period (1900-2002) and for the two halves of the full period. Applied statistical tests were significant, evidencing that the climatic signal could be reconstructed. The reconstructed precipitation anomalies show interdecadal shifts, and rainfall decrease within the coldest period of the LIA and during the second half of the 20th century, probably associated to current Global Warming. Neither increasing nor decreasing linear trends or periods of extreme precipitation events were identified. Our results are coherent with other palaeohydrological reconstructions for northern Iberian Peninsula. Correlations between the predicted autumn precipitation and the main teleconnections -NAO, ENSO and WEMO- were weak, although a potential relationship with the Atlantic Multidecadal Oscillation (AMO) pattern is suggested. The obtained reconstruction provides the first estimations of regional autumn precipitation shifts i

© 2021. The Authors. Esther González did intensive work at the UK National Archives abstracting logbooks. The research was funded by the Spanish Ministerio de Economía y Competitividad under grant CGL2015-72164-EXP (UPNAO). Support for the 20th Century Reanalysis Project version 3 data set is provided by the U.S. Department of Energy, Office of Science Biological and Environmental Research (BER), by the National Oceanic and Atmospheric Administration Climate Program Office, and by the NOAA Physical Sciences Laboratory. Funding for open access publishing: Universidad Pablo de Olavide/CBUA., In this study, we make use of historical wind direction observations to assemble an instrumental upwelling index (DUI) at the southern end of the Canary Current Upwelling System. The DUI covers the period between 1825 and 2014 and, unlike other upwelling indices, it does not rely neither in wind speed nor in reanalyzed data. In this sense, the DUI can be regarded as an instrumental index. Additionally, it avoids the suspected bias toward increasing wind speed of historical wind observations documented in previous research. Our results indicate that the frequency of the alongshore winds at the west coast of Africa between 10°N and 20°N measured by the DUI is significantly related with the wind stress and therefore the upwelling intensity in this region. The DUI presents a significant variability both at interannual and decadal timescales. We have not found any significant trend for the 20th century. However, when the entire length of the series is considered, a large shift toward more frequent alongshore winds is evidenced as a result of several decade-long fluctuations which took place between the late 19th century and the beginning of the 20th century. This fact would imply that a significant change in the upwelling intensity at the southern end of the Canary Current Upwelling System should have occurred at the turn of the 20th century., Ministerio de Economía y Competitividad (MINECO), United States Department of Energy (DOE), National Oceanic Atmospheric Admin (NOAA) - USA, NOAA Physical Sciences Laboratory, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2020 The Author(s). Artículo firmado por 14 autores. This work was supported by the research projects CGL2017-82216-R, CGL2017-83866-C3-3-R and PCI2019-103631, financed by the Spanish Commission of Science and Technology and FEDER; CROSSDRO project financed by the AXIS (Assessment of Cross(X)—sectoral climate Impacts and pathways for Sustainable transformation), JPI-Climate cofunded call of the European Commission and INDECIS which is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462). Dhais Peña-Angulo received a ‘Juan de la Cierva’ postdoctoral contract (FJCI2017-33652 Spanish Ministry of Economy and Competitiveness, MEC). Conor Murphy was supported by the Irish Environmental Protection Agency (Grant Nos. 2019-CCRP-MS.60). Marco Turco has received funding from the Spanish Ministry of Science, Innovation and Universities through the project PREDFIRE (RTI2018-099711-J-I00), which is cofinanced with the European Regional Development Fund (ERDF/FEDER)., We present a long-term assessment of precipitation trends in Southwestern Europe (1850–2018) using data from multiple sources, including observations, gridded datasets and global climate model experiments. Contrary to previous investigations based on shorter records, we demonstrate, using new long-term, quality controlled precipitation series, the lack of statistically significant long-term decreasing trends in precipitation for the region. Rather, significant trends were mostly found for shorter periods, highlighting the prevalence of interdecadal and interannual variability at these time-scales. Global climate model outputs from three CMIP experiments are evaluated for periods concurrent with observations. Both the CMIP3 and CMIP5 ensembles show precipitation decline, with only CMIP6 showing agreement with long term trends in observations. However, for both CMIP3 and CMIP5 large interannual and internal variability among ensemble members makes it difficult to identify a trend that is statistically different from observations. Across both observations and models, our results make it difficult to associate any declining trends in precipitation in Southwestern Europe to anthropogenic forcing at this stage., Unión Europea. Horizonte 2020, Ministerio de Ciencia e Innovación (MICINN)/FEDER, Ministerio de Economía y Competitividad (MINECO), the AXIS (Assessment of Cross(X)—sectoral climate Impacts and pathways for Sustainable transformation), Irish Environmental Protection Agency, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Modes of climate variability affect global and regional climates on different spatio-temporal scales, and they have important impacts on human activities and ecosystems. As these modes are a useful tool for simplifying the understanding of the climate system, it is crucial that we gain improved knowledge of their long-term past evolution and interactions over time to contextualise their present and future behaviour. We review the literature focused on proxy-based reconstructions of modes of climate variability during the Holocene (i.e., the last 11.7 thousand years) with a special emphasis on i) proxy-based reconstruction methods; ii) available proxy-based reconstructions of the main modes of variability, i.e., El Nino Southern Oscillation, Pacific Decadal Variability, Atlantic Multidecadal Variability, the North Atlantic Oscillation, the Southern Annular Mode and the Indian Ocean Dipole; iii) major interactions between these modes; and iv) external forcing mechanisms related to the evolution of these modes. This review shows that modes of variability can be reconstructed using proxy-based records from a wide range of natural archives, but these reconstructions are scarce beyond the last millennium, partly due to the lack of robust chronologies with reduced dating uncertainties, technical issues related to proxy calibration, and difficulty elucidating their stationary impact (or not) on regional climates over time. While for each mode the available reconstructions tend to agree at mutidecadal timescales, they show notable disagreement on shorter timescales beyond the instrumental period. The reviewed evidence suggests that the intrinsic variability of modes can be modulated by external forcing, such as orbital, solar, volcanic, and anthropogenic forcing. The review also highlights some modes experience higher variability over the instrumental period, which is partly ascribed to anthropogenic forcing. These features stress the paramount importance of further studying

The North Atlantic Oscillation (NAO) is the major atmospheric mode that controls winter European climate variability because its strength and phase determine regional temperature, precipitation and storm tracks. The NAO spatial structure and associated climatic impacts over Europe are not stationary making it crucial to understanding its past evolution in order to improve the predictability of future scenarios. In this regard, there has been a dramatic increase in the number of studies aimed at reconstructing past NAO variability, but the information related to decadal-scale NAO evolution beyond the last millennium is scarce and inconclusive. We present a new 2,000-year multi-annual, proxy-based reconstruction of local NAO impact, with associated uncertainties, obtained by a Bayesian approach. This new local NAO reconstruction is obtained from a mountain lacustrine sedimentary archive of the Iberian Peninsula. This geographical area is not included in previous NAO reconstructions despite being a widely used region for instrumental-based NAO measurements. We assess the main external forcings (i.e., volcanic eruptions and solar activity) on NAO variability which, on a decadal scale, show that a low number of sunspots correlate to low NAO values. By comparison with other previously published NAO reconstructions in our analyses we can test the stationarity of the solar influence on the NAO signal across a latitudinal gradient based on the position of the employed archives for each NAO reconstruction. Inconclusive results on the volcanic forcing on NAO variability over decadal time-scales indicates the need for further studies. Moreover, we highlight the potential role of other North Atlantic modes of variability (i.e., East Atlantic pattern) on the non-stationary behaviour of the NAO throughout the Common Era, likely via solar forcing.