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

Comparison between two design methods implants, based on reverse engineering, design and engineering technologies, BIOCAD/CAD/CAE

Resumen El principal propósito del presente artículo de investigación, fue comparar dos métodos usados para el diseño y evaluación biomecánica de implantes dentales. El primer método se desarrolló basado en la integración de una técnica imagenológica usada en diagnóstico de imágenes tomográficas, para la reconstrucción de modelos 3D virtuales óseos con herramientas software de ingeniería inversa, articulada al diseño aplicado en ingeniería e ingeniería mecánica aplicada. En el segundo método, la probeta de mandíbula fue modelada en un software CAD (Computer Aided Design) que fue utilizado para el diseño del implante; posteriormente fue realizado la simulación biomecánica estática en un entorno CAE (Computer Aided Engineering), aplicando cargas incrementales de torque de inserción en la interfase hueso implante. Los análisis por simulación en ambos métodos fueron realizados basados en los mismos criterios de evaluación. Se corroboró por simulación los valores de torque de inserción apropiados para mantener una adecuada relación en la interfase hueso implante. Por otra parte los resultados obtenidos por la aplicación de cada método de diseño fueron analizados y comparados para conocer el efecto de la integración de las técnicas imagenológicas apropiadas desde el software Bio CAD y articulado con las tecnologías software CAD CAE. Abstract The main objective of this research work was to make a comparison between two methods used for design and biomechanical assessment of dental implants.. The first method is based on integration of an imaging technique used in diagnosis of tomographic images applied to 3D bone model reconstruction with reverse engineering software tools implemented on engineering applications. In the second method a specimen of jaw modeled in CAD (Computer Aided Design) software used to implant design was implemented, then a static simulation biomechanics was performed in a CAE (Computer Aided Engineering) environment, applying elementary insertion torque loads at the bone-implant interface. Simulations Analysis were performed for both methods, using the same evaluation criteria. Appropriate insertion torque values were confirmed with simulations as appropriate to maintain a proper relationship at the bone-implant interface. The results obtained using each method were analyzed and compared to determine the effect on appropriate integration of BioCAD imaging techniques and articulation with Technologies CAD and CAE

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

Comparando procesos nivales sobre diferentes cordilleras ibéricas

13 páginas.- Presentación elaborada para las Jornadas IPErinas 2016, celebradas en Zaragoza, el 15 de diciembre de 2016Peer reviewe

Assessing the Impact of Different Measurement Time Intervals on Observed Long-Term Wind Speed Trends

During the last two decades climate studies have reported a tendency toward a decline in measured near-surface wind speed in some regions of Europe, North America, Asia and Australia. This weakening in observed wind speed has been recently termed >global stilling>, showing a worldwide average trend of -0.140 m s -1 dec -1 during last 50-years. The precise cause of the >global stilling> remains largely uncertain and has been hypothetically attributed to several factors, mainly related to: (i) an increasing surface roughness (i.e. forest growth, land use changes, and urbanization); (ii) a slowdown in large-scale atmospheric circulation; (iii) instrumental drifts and technological improvements, maintenance, and shifts in measurements sites and calibration issues; (iv) sunlight dimming due to air pollution; and (v) astronomical changes. This study proposed a novel investigation aimed at analyzing how different measurement time intervals used to calculate a wind speed series can affect the sign and magnitude of long-term wind speed trends. For instance, National Weather Services across the globe estimate daily average wind speed using different time intervals and formulae that may affect the trend results. Here we analyzed near-surface wind speed trends recorded at 19 land-based stations across Spain comparing monthly mean wind speed series obtained from: (a) daily mean wind speed data averaged from standard 10-min mean observations at 0000, 0700, 1300 and 1800 UTC; and (b) average wind speed of 24 hourly measurements (i.e., wind run measurements) from 0000 to 2400 UTC. As a complementary analysis, in this study we also quantified the impact of anemometer drift (i.e. bearing malfunction) by presenting preliminary results (i.e. 11 months of paired measurements) from a comparison of one new anemometer sensor against one malfunctioned anemometer sensor due to old bearings.We would like to thank the AEMET for supplying wind speed data. C. A-M. received a postdoctoral fellowship # JCI-2011-10263. Research supported by projects CGL2011-27574-C02-02, CGL2011-27536/HID and CGL2011-29263-C02-01 financed by the Spanish Commission of Science and Technology.Peer Reviewe

Evapotranspiration deficit controls net primary production and growth of silver fir: Implications for Circum-Mediterranean forests under forecasted warmer and drier conditions

Warming-induced drought stress has been hypothesized as a major driver of forest net primary production (NPP) reduction, but we lack reliable field data to assess if higher temperatures lead to forest NPP reduction, particularly in humid sites and at basin to landscape spatial scales. The use of a landscape approach would allow considering the feedbacks operating between climate, topography, soil vegetation and water resources. Here we follow that approach by simulating NPP using the regional hydro-ecologic simulation system (RHESSys) model and by comparing the results with radial growth data (tree-ring widths and intrinsic water-use efficiency - iWUE). We evaluate the relationships between climate, growth, NPP, atmospheric CO2 concentrations (ca) and iWUE in xeric and mesic silver fir forests subjected to contrasting water balances. The growth data successfully validated the 11-month NPP cumulated until spring. The main negative climatic driver of growth and NPP was the summer evapotranspiration deficit, which shows a negative association with tree-ring width indices. Sensitivity analyses indicate that rising ca do not compensate the severe NPP reduction associated to warmer and drier conditions. The positive effect of rising ca on NPP is mediated by climatic site conditions being detected only in mesic sites, whereas the negative effects of drought on NPP override any ca-related enhancement of NPP in xeric sites. Future warmer and drier conditions causing a higher evaporative demand by the atmosphere could lead to a NPP decline in temperate conifer forests subjected to episodic droughts. © 2015 Elsevier B.V.We would like to thank the Spanish Meteorological State Agency (AEMET) and the Confederación Hidrográfica del Ebro for providing the climatic and streamflow databases used in this study. This work has been supported by research projects CGL2011-27574-CO2-02, CGL2011-27536, CGL2014-52135-CO3-01 and Red de variabilidad y cambio climático RECLIM (CGL2014-517221-REDT) financed by the Spanish Commission of Science and Technology and FEDER, “LIFE12 ENV/ES/000536-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 and CTTP1/12 financed by the Comunidad de Trabajo de los Pirineos. JJC also acknowledges the support of ARAID and projects 012/2008, 387/2011 and 1012S (Organismo Autónomo Parques Nacionales, Spain).Peer Reviewe

Subgrid snow depth coefficient of variation spanning alpine to sub-alpine mountainous terrain

Given the substantial variability of snow in complex mountainous terrain, a considerable challenge of coarse scale modeling applications is accurately representing the subgrid variability of snowpack properties. The snow depth coefficient of variation (CVds) is a useful metric for characterizing subgrid snow distributions but has not been well defined by a parameterization for mountainous environments. This study utilizes lidar-derived snow depth datasets spanning alpine to sub-alpine mountainous terrain in Colorado, USA to evaluate the variability of subgrid snow distributions within a grid size comparable to a 1000 m resolution common for hydrologic and land surface models. The subgrid CVds exhibited a wide range of variability across the 321 km2 study area (0.15 to 2.74) and was significantly greater in alpine areas compared to subalpine areas. Mean snow depth was the dominant driver of CVds variability in both alpine and subalpine areas, as CVds decreased nonlinearly with increasing snow depths. This negative correlation is attributed to the static size of roughness elements (topography and canopy) that strongly influence seasonal snow variability. Subgrid CVds was also strongly related to topography and forest variables; important drivers of CVds included the subgrid variability of terrain exposure to wind in alpine areas and the mean and variability of forest metrics in subalpine areas. Two statistical models were developed (alpine and subalpine) for predicting subgrid CVds that show reasonable performance statistics. The methodology presented here can be used for characterizing the variability of CVds in snow-dominated mountainous regions, and highlights the utility of using lidar-derived snow datasets for improving model representations of snow processes

Ekstrakcija prirodnog žutog bojila iz plodova opuncije

This paper focuses on the development of a processing scheme to obtain a water-soluble natural yellow colourant from Opuntia fruits for application in food, paying special attention to the extraction procedure. Edible yellow Opuntia fruits grown in Murcia (Spain) were homogenized and extracted with ethanol, water, or ethanol/water (60:40) solvents. Pigment extract was chemically characterized and individual pigments were identified by high-performance liquid chromatography (HPLC), UV-VIS spectrophotometry, and electrospray ionization mass spectroscopy. A sequential extraction procedure was determined as follows: homogenization, stirring, centrifugation, filtration and concentration. The highest betaxanthin content per kg of fresh pulp (0.68 mmol of indicaxanthin) was obtained from the hydroalcoholic extract, and moreover, this solvent minimized the presence of mucilage and pectins, which are substances not desired in dye extracts. A concentrated pigment extract was obtained under rotary evaporation at 35 °C and reduced pressure (6 kPa), with a betaxanthin concentration (expressed as indicaxanthin) of 0.27 g/L, and CIELAB values of L*=92.7, a=–0.8 and b*=68.5. The individual pigment HPLC analysis with photodiode array and mass spectral detection revealed that proline-betaxanthin (indicaxanthin) was clearly dominant, while all other betalains were present in comparatively low quantities. The pigment stability was checked at 4 and 25 °C. Kinetics analyses indicate that the betaxanthin degradation pattern can be approximated as pseudo-first-order kinetics.U središtu je istraživanja bio razvoj proizvodne sheme, tj. postupak ekstrakcije prirodnog, žutog, vodotopljivog prehrambenog bojila iz plodova opuncije. Bojilo je ekstrahirano etanolom, vodom te smjesom etanola i vode u omjeru 60:40 iz samljevenih (homogeniziranih) jestivih žutih plodova opuncije, uzgojenih u španjolskoj pokrajini Murcia. Ispitan je kemijski sastav dobivenog ekstrakta, a pojedini su pigmenti određeni visokodjelotvornom tekućinskom kromatografijom (HPLC), ultraljubičastom/vidljivom (UV/VIS) spektrofotometrijom i ionizacijom elektroraspršivanjem. Sekvencijska ekstrakcija obuhvaćala je ove postupke: homogenizaciju, miješanje, centrifugiranje, filtraciju i ugušćivanje. Najveći je udjel betaksantina u kg svježe pulpe (0,68 mmol indikaksantina) dobiven ekstrakcijom pomoću alkohola i vode koja je smanjila udjel nepoželjnih sastojaka u pigmentu (sluzi i pektina). Koncentrirani je ekstrakt dobiven u rotirajućem isparivaču pri 35 °C i 6 kPa, pri čemu je koncentracija betaksantina (izražena kao indikaksantin) bila 0,27 g/L, a CIELAB vrijednosti bile su: L*=92,7, a=-0,8 i b*=68,5. HPLC analizom pojedinog pigmenta pomoću fotodiode i masenog detektora utvrđeno je da u ekstraktu prevladava betaksantin kao derivat prolina (indikaksantin), dok su ostali betalaini bili manjih koncentracija. Ispitana je stabilnost pigmenta pri 4 i 25 °C. Kinetička je analiza pokazala da se degradacija betaksantina može opisati reakcijom pseudoprvog reda