Atmospheric circulation influence on the interannual variability of snow pack in the Spanish Pyrenees during the second half of the 20th century

12 páginas, 5 figuras, 6 tablas.Large areas in the Spanish Pyrenees are covered by snow between December and April, especially above 1650 m a.s.l., the location of the cold season 0°C isotherm. However, a significant negative trend in Pyrenean snow pack was detected during the second half of the 20th century. This paper analyses the interannual evolution of snow accumulation in these mountains in relation to the variability of atmospheric circulation. The study considers two spatial scales, from weather types over the Iberian Peninsula to hemispheric atmospheric patterns. The results show strong relationships between the annual occurrence of several weather types and spring snow accumulation. Changes in the frequency of several weather types are explained by the evolution of large scale hemispheric circulation patterns, especially the North Atlantic Oscillation (NAO). Thus, the positive trend observed in the NAO index leads to a decrease in the occurrence of types that favour snow accumulation and an increase in unfavourable conditions for snow pack during the second half of the 20th century.This study was supported by the following research projects: PIRIHEROS, REN 2003- 08678/HID, CGL2005-04508/BOS and CANOA, CGL 2004-04919-c02-01, all funded by the CICYT, Spanish Ministry of Science and Technology. The research of the authors was supported by postdoctoral fellowships from the Spanish Ministry of Education, Culture and Sports, Spain.Peer reviewe

A Multiscalar Global Drought Dataset: The SPEIbase: A New Gridded Product for the Analysis of Drought Variability and Impacts

A new multiscalar drought dataset, the SPEIbase, made available to the scientific and management community is presented. The multiscalar character of the dataset allows finding the most appropriate time scale of interest for a specific application, so potential uses of the dataset range over a wide variety of disciplines. The dataset (in three file formats) is distributed under an open license. Further work includes updating the dataset past December 2006, depending on the data availability.This work has been supported by the research projects CGL2008-01189/BTE and CGL2006-11619/HID, funded by the Spanish Commission of Science and Technology and FEDER; EUROGEOSS (FP7-ENV-2008-1-226487) and ACQWA (FP7-ENV-2007-1- 212250), funded by the VII Framework Programme of the European Commission; and “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 climática,” funded by “Obra Social La Caixa” and the Aragón Government.Peer reviewe

Variabilidad espacial de los efectos socioeconómicos de las explotaciones de esquí alpino en los municipios rurales del Pirineo aragonés

22 páginas, 9 figuras, 4 tablas.[ES] Desde mediados del siglo XX se han impulsado las estaciones de esquí alpino en el Pirineo Aragonés, para incentivar las actividades turísticas y generar nuevas vías de desarrollo socio-económico. Transcurridos más de 30 años desde la construcción de las estaciones de esquí, cabe plantearse ¿en qué medida han contribuido a un desarrollo homogéneo en el territorio o han contribuido a desequilibrios espaciales? En este trabajo se estudian los efectos del turismo en la dinámica de la población (evolución del censo, cambios en la estructura demográfica y distribución de la población activa) y en el sector primario (evolución del número de explotaciones y de los censos ganaderos). Los resultados obtenidos en este trabajo permiten concluir que en el Pirineo Aragonés las estaciones de esquí afectan a un área espacial bastante reducida. En los municipios incluidos en ella se observan resultados positivos respecto a la evolución demográfica y negativos en el mantenimiento del sector primario. En los municipios no afectados por las estaciones de esquí, los resultados son totalmente diferentes, mostrando una evolución muy negativa de la población y positiva de los censos ganaderos[EN] Tourist activities, especially those related to skiing, have been promoted in the central Spanish Pyrenees since the 1950s. Using a 30-year dataset extending back to before the development of most ski resorts in the Pyrenees, we analysed the effects of ski resort development on the human population (change in the number of inhabitants, demographic structure and structure of the working sector) and the primary production activities of the area (number of farms and livestock). Spatial differences that have occurred in the socioeconomic changes since ski resort construction began are also analysed. Results show that the area influenced by ski resorts is restricted to the municipalities nearest to them. These municipalities show positive demographic changes and a negative evolution of primary activities. The municipalities more distant from the ski resorts show the opposite pattern. The advantages and problems of ski resort-based tourism in relation to the sustainable development of the Pyrenees are discussed in depth.[FR] Depuis la moitié du XXème siècle des nombreuses stations de ski alpin ont été créées dans les Pyrénées Aragonaises a fin de promouvoir les activités touristiques et de favoriser le développement socio-économique dans la région. Trente années sont passées depuis la construction des dernières stations de ski, et il faut se demander dans quelle mesure elles ont contribué à un développement homogène dans le territoire ou à des déséquilibres spatiaux. Dans ce travail on étudie les effets du tourisme sur la dynamique de la population (évolution de la population, changements de la structure démographique et de la distribution de la population active) ainsi que sur le secteur primaire (évolution du nombre d´exploitations et des effectifs de l’élevage). Les résultats obtenus dans ce travail permettent de conclure que dans les Pyrénées Aragonaises les stations de ski affectent des espaces assez réduits. On observe, dans les communes des zones affectées, des résultats positifs concernant l´évolution démographique, et négatifs quant au maintien du secteur primaire. Dans les communes qui ne sont pas affectées par les stations de ski les résultats sont très différents, avec une évolution très négative de la population et positive des effectifs animaux.Este trabajo se ha realizado con la ayuda de los proyectos: GGL2005- 04863/CLI, CGL2005-04508/BOS, financiados por la CICYT y FEDER, PIP098/2005 y PIP176/2005, financiados por el Gobierno de Aragón, y “Programa de grupos de investigación” (BOA 48 de 20-04-2005), también financiados por el Gobierno de Aragón.Peer reviewe

Incertidumbre en la disponibilidad de recursos hídricos superficiales en la Cuenca del Ebro: análisis temporal desde una perspectiva plurisecular

Using dendroclimatic reconstructions of annual precipitation in Capdella (Central-Eastern Pyrenees) and Pallaruelo de Monegros (Central Ebro Valley), rainfall evolution in Ebro Valley since 16th century is analyzed. These reconstructions show precipitation fluctuations in both climatic areas. The main anomalies occur in 16th and 17th centuries, during Little Ice Age, as well as in the second half of 20th century. Furthermore, dendroclimatic reconstructions allow LIS to evaluate some probabilistic analysis applied in hydrologic rnanagement.A partir de las reconstrucciones dendroclimáticas de los totales anuales de precipitación de Capdella (Pirineo Centro-Oriental) y Pallaruelo de Monegros (sector central del Valle del Ebro), se analiza la evolución de la pluviometría en la Cuenca del Ebro desde el siglo XVI. Estas reconstrucciones evidencian el carácter oscilante de la precipitación en los dos ambientes climáticos. Las anomalías pluviométricas más importantes aparecen en los siglos XVI y XVII, durante la Pequeña Edad del Hielo, y en la segunda mitad del siglo XX. Posteriormente, las series dendroclimáticas se utilizan para evaluar la validez de algunos análisis probabilisticos utilizados como herramientas de gestión y planificación hidrológica

An assessment of the role of homogenization protocol in the performance of daily temperature series and trends: Application to northeastern Spain

[EN] This paper gives the complete details of the protocols applied for developing a spatially and temporarily high-resolution dataset of temperature for northeastern Spain. Our methodologies used data from a large number of observatories (1583) spanning some portions of the period between 1900 and 2006. The raw dataset was first tested for internal and external consistency to check data quality. To improve data completeness, a linear regression model was then utilized to infill gaps in the daily temperature series using the best correlated data from nearby sites. Discontinuities in the reconstructed series were determined by combining the results of three homogeneity-relative tests: the Standard Normal Homogeneity Test (SNHT), the Eastrerling and Peterson two-phased regression method and the Vincent test. To assess the possible impact of data homogenisation on trends and statistical properties of the final series, a set of tests (e.g. semivariance models and L-moment statistics) was applied to the series before and after correction. Semivariance models suggest a significant improvement in the spatial dependence of the corrected dataset on both seasonal and annual timescales. Also, L-moments gave no evidence of significant changes in the probability distribution of daily temperature series after correction. Taken together, the newly compiled dataset seems to be more robust and reveals more coherent spatial and temporal patterns of temperature compared with the original dataset. From the temporal and spatial perspectives, the new dataset comprises the most complete register of temperature in northeast Spain (1900-2006), with a reasonably spatial coverage. Accordingly, this database can provide a more reliable base for studying temperature changes and variability in the region. This dataset can also be of particular relevance to a number of meteorological, ecological, hydrological and agricultural applications on local, regional and continental scales. © 2011 Royal Meteorological Society.We are indebted to the anonymous reviewers for their constructive comments which were most helpful in improving this paper. We would like to thank the Agencia Estatal de Meteorologia for providing the temperature data used in this study. This work has been supported by the research projects CGL2006-11619/HID, CGL2008- 01189/BTE, CGL2011-27574-CO2-02, CGL2011-27753- CO2-01 and CGL2011-27536 financed by the Spanish Commission of Science and Technology; and also FEDER, EUROGEOSS (FP7-ENV-2008-1-226487) and ACQWA (FP7-ENV-2007-1- 212250) financed by the VII Framework Programme of the European Commission, La nieve en el Pirineo Aragones y su respuesta a ´ la variabilidad climatica, and Efecto de los escenarios ´ de cambio climatico sobre la hidrolog ´ ´ıa superficial y la gestion de embalses del Pirineo Aragon ´ es, financed by ´ Obra Social La Caixa and the Aragon Government and ´ Influencia del cambio climatico en el turismo de nieve, ´ CTTP01/10, financed by the Comision de Trabajo de los ´ Pirineos.Peer Reviewe

Reference crop evapotranspiration database in Spain (1961-2014)

Obtaining climate grids describing distinct variables is important for developing better climate studies. These grids are also useful products for other researchers and end users. The atmospheric evaporative demand (AED) may be measured in terms of the reference evapotranspiration (ETo), a key variable for understanding water and energy terrestrial balances and an important variable in climatology, hydrology and agronomy. Despite its importance, the calculation of ETo is not commonly undertaken, mainly because datasets consisting of a high number of climate variables are required and some of the required variables are not commonly available. To address this problem, a strategy based on the spatial interpolation of climate variables prior to the calculation of ETo using FAO-56 Penman-Monteith equation was followed to obtain an ETo database for continental Spain and the Balearic Islands, covering the 1961-2014 period at a spatial resolution of 1.1 km and at a weekly temporal resolution. In this database, values for the radiative and aerodynamic components as well as the estimated uncertainty related to ETo were also provided. This database is available for download in the Network Common Data Form (netCDF) at https://doi.org/10.20350/digitalCSIC/8615 (Tomas-Burguera et al., 2019). A map visualization tool (http://speto.csic.es, last access: 10 December 2019) is available to help users download the data corresponding to one specific point in comma-separated values (csv) format. A relevant number of research areas could take advantage of this database. For example, (i) studies of the Budyko curve, which relates rainfall data to the evapotranspiration and AED at the watershed scale, (ii) calculations of drought indices using AED data, such as the Standardized Precipitation-Evapotranspiration Index (SPEI) or Palmer Drought Severity Index (PDSI), (iii) agroclimatic studies related to irrigation requirements, (iv) validation of climate models'' water and energy balance, and (v) studies of the impacts of climate change in terms of the AED

Application of the Standardized Precipitation Evapotranspiration Index (SPEI) for drought analysis and monitoring: characteristics, recommendations and comparison with other indices

The complexity of drought quantification and analysis: • Droughts are difficult to pinpoint in time and space given different economic sectors and natural systems affected. • We identify a drought by its effects or impacts on different types of systems (agriculture, water resources, ecology, forestry, economy, etc.), but there is not a physical variable we can measure to quantify droughts. • Long-term drought objective metrics (streamflows, soil moisture, lake levels, etc.) are commonly not available. Moreover, using only objective metrics other relevant variables to determine drought severity (e.g. the atmospheric water demand) are not taken into account. • We use the so-called “DROUGHT INDICES” for drought quantification and analysis. Standardized Precipitation Evapotranspiration Index (SPEI): The SPEI uses the difference between precipitation and ETo. This represents a simple climatic water balance which is calculated at different time scales to obtain the SPEI. With a value for ETo, the difference between the precipitation (P) and PET for the month i is calculated according to: Di = Pi-EToi, The calculated D values are aggregated at different time scalesPeer Reviewe

Aproximación al estudio de las sequías en las subcuencas de cabecera de la España peninsular: análisis de correlación entre índices de sequía climáticos e hidrológicos, tipos de vegetación y actividad vegetal.

El presente trabajo final de máster se ha desarrollado con motivo de la beca JAE Intro 2018 realizada en el Instituto Pirenaico de Ecología en Zaragoza (IPE) del Consejo Superior de Investigaciones Científicas (CSIC). Se trata de una aproximación al estudio de las sequías en las subcuencas de cabecera de la España peninsular en diferentes períodos según la información disponible a través de un análisis de correlación entre distintos indicadores climáticos e hidrológicos: 1) Índice Estandarizado de Precipitación (SPI); 2) Índice Estandarizado de Precipitación y Evapotranspiración (SPEI); 3) Índice Estandarizado de Caudales (SSI). Además de ello se ha utilizado información de variables auxiliares como el caso de: 1) el Índice de Vegetación de Diferencia Normalizada (NDVI); 2) las coberturas del suelo del Corine Land Cover (CLC) 1990, 2000, 2006 y 2012. Se analiza la interacción entre las sequías climáticas e hidrológicas y sus variaciones espaciales en 214 subcuencas de cabecera de la España peninsular. Además, también se analiza la influencia que presenta la vegetación en la relación entre ambos tipos de sequía. Mediante un análisis de correlación se compara el comportamiento de las sequías en la zona de estudio y se determina la respuesta de los diferentes sistemas naturales a las sequías climáticas e hidrológicas. Se ha relacionado el índice de sequía hidrológica SSI, el índice de vegetación NDVI y las coberturas del suelo del CLC con la variabilidad climática recogida en los índices SPI y SPEI. Con ello se puede determinar el retardo temporal y las escalas temporales óptimas en la evaluación de la relación entre las sequías climáticas y las hidrológicas. Además, el NDVI y las coberturas del CLC se relacionan con el SSI para analizar la posible influencia de la cubierta vegetal en la relación existente entre los índices de sequía climáticos e hidrológicos. <br /

Influencia de la ganadería en la evolución del riesgo de incendio en función de la vegetación en un área de montaña: el ejemplo del valle de Borau (Pirineo aragonés)

The study concerns the impact of livestock on the fire-risk evolution in Borau valley (Pyrenees) between 1957 and 2000. The risk has grown considerably due to an increase in pine woods and scrub areas because of land abandonment and livestock extensification. The decrease in livestock pression has been crucial in the potential firerisk increase. The decline of stay sheep and the extensification of their shepherding areas have been the most important factors in the process.Se ha estudiado la influencia de la ganader&iacute;a en la evoluci&oacute;n del riesgo de incendio en funci&oacute;n de la vegetaci&oacute;n en el valle de Borau (Pirineo aragon&eacute;s) entre 1957 y 2000. Se ha comprobado que el riesgo ha aumentado considerablemente a lo largo del periodo estudiado como consecuencia del incremento de los bosques de con&iacute;feras y de la vegetaci&oacute;n arbustiva, fruto del abandono de campos de cultivo y de la extensificaci&oacute;n ganadera. El descenso de la presi&oacute;n ganadera ha intervenido de forma determinante en el incremento del potencial riesgo de incendio. El factor m&aacute;s importante ha sido el retroceso del ganado lanar estante y la extensificaci&oacute;n de sus &aacute;reas de pastoreo