Suchergebnisse

À partir de 1989, suite à la profonde crise économique que connut le Mexique, le mode de régulation des professions de l'éducation supérieure a radicalement changé. La rémunération du travail, auparavant essentiellement salarial (c'est-à-dire garantie par des Conventions Collectives) perdait 60 % de sa valeur. Par la suite, le redressement progressif du revenu des personnels académiques, ne s'est pas fait par des augmentations salariales, mais par la mise en place de programmes laissant aux enseignants à temps plein la possibilité d'obtenir des ressources supplémentaires, « payées au mérite », individuellement et hors-salaire, sous condition d'évaluation positive de leur production académique. Aujourd'hui, la part du salaire dans le revenu de l'élite de l'enseignement supérieur est tombée à tout juste 30 %, l'essentiel étant composé de prestations ou de récompenses additionnelles et irrégulières. En nous penchant sur le modèle des Transferts Monétaires Conditionnés, nous montrerons les réussites et les limites d'un tel système, ainsi que les effets contradictoires qu'il peut engendrer.

Sin duda, el congreso universitario de la UNAM contara entre sus temas con el asunto de la democratizacion de la vida universitaria. Para ser fructifero tendra que delimitar a que se hace referencia cuando se habla de democracia en la universidad

This paper provides an account of observed variations in Black carbon (BC) aerosol concentrations and their induced radiative forcing for the first time over Granada a measurement site in Southeastern Iberian Peninsula. Column-integrated BC concentrations were retrieved for the period 2005–2012. Monthly averages of BC concentrations (± one standard deviation) ranged from higher values in January and December with 4.0 ± 2.5 and 4 ± 3 mg/m², respectively, to lower values in July and August with 1.6 ± 1.2 and 2.0 ± 0.5 mg/m², respectively. This reduction is not only observed in the average values, but also in the median, third and first quartiles. The average BC concentration in winter (3.8 ± 0.6 mg/m²) was substantially higher than in summer (1.9 ± 0.3 mg/m²), being the eight-year average of 2.9 ± 0.9 mg/m². The reduction in the use of fossil fuels during the economic crisis contributed significantly to reduced atmospheric loadings of BC. According to our analysis this situation persisted until 2010. BC concentration values were analyzed in terms of air mass influence using cluster analysis. BC concentrations for cluster 1 (local and regional areas) showed high correlations with air masses frequency in winter and autumn. In these seasons BC sources were related to the intense road traffic and increased BC emissions from domestic heating. High BC concentrations were found in autumn just when air mass frequencies for cluster 3 (Mediterranean region) were more elevated, suggesting that air masses coming from that area transport biomass burning particles towards Granada. BC aerosol optical properties were retrieved from BC fraction using aerosol AERONET size volume distribution and Mie theory. A radiative transfer model (SBDART) was used to estimate the aerosol radiative forcing separately for composite aerosol (total aerosols) and exclusively for BC aerosols. The mean radiative forcing for composite aerosol was + 23 ± 6 W/m² (heating rate of + 0.21 ± 0.06 K/day) and + 15 ± 6 W/m² for BC aerosol (heating rate of + 0.15 ± 0.06 K/day). These values of radiative forcing and heating rate for BC aerosol represent about 70% of their values for composite aerosol, which highlights the crucial role that BC aerosols play in modifying the radiation budget and climate. ; This work was supported by the Andalusia Regional Government through project P12-RNM-2409, by the Spanish Ministry of Economy and Competitiveness through projects CGL2013-45410-R and CGL2016-81092-R and by the European Union's Horizon 2020 research and innovation programme through project ACTRIS-2 (grant agreement No. 654109). The authors thankfully acknowledge the FEDER program for the instrumentation used in this work. Antonio Valenzuela thanks Universidad de Granada for the award of a postdoctoral grant ("Plan Propio. Programa 8. Convocatoria 2014"). The work is co-funded by the European Union through the European Regional Development Fund, included in the COMPETE 2020 (Operational Program Competitiveness and Internationalization) through the ICT project (UID/GEO/04683/2013) with the reference POCI-01-0145-FEDER-007690. CIMEL Calibration was performed at the AERONET-EUROPE calibration center, supported by ACTRIS (European Union Seventh Framework Program (FP7/2007-2013) under grant agreement no. 262254. The authors express gratitude to the NOAA Air Resources Laboratory (ARL) for the HYSPLIT transport and dispersion model (http://ready.arl.noaa.gov/HYSPLIT.php). The author acknowledges the funding provided by the Institute of Earth Sciences (ICT), under contracts UID/GEO/04683/2013 with FCT (the Portuguese Science and Technology Foundation), and COMPETEPOCI-01-0145-FEDER-007690.

Sky imagers have been used for cloud detection and classification in the last years, and one of the applications of these instruments is the use of cloud information in forecast algorithms for solar power technologies. These algorithms depend on an accurate classification of the complete sky dome cloud cover, but most system fail in the proximity of the sun due to saturation in the images. This work proposes a new method for cloud detection with sky imagers using images taken with different exposure times and applying an adaptive threshold to each one. The use of multiple exposure times avoids the saturation of the image in the vicinity of the sun position, while the adaptive threshold applied to the images helps in the accurate detection of cloud coverage, especially in the circumsolar area. The method is tested with a commercial sky imager, paying special attention to the detection of clouds close to the sun position. A case study is analyzed, showing an accurate detection of clouds in the vicinity of the sun. The method is also validated using statistical values for data recorded during almost one month which cover a great variety of cloudiness cases. For this purpose, the detection of clouds in the sun position is compared against the reduction of the direct normal irradiance (DNI) with respect to a modeled DNI. ; This work was supported by the Andalusia Regional Government through projectsP10-RNM-6299 and P12-RNM-2409, ; Spanish Ministry of Economy and Competitiveness through projectsCGL2013-45410-R. ; EU through ACTRIS project (EU INFRA-2010-1.1.16-262254).

A methodology to obtain the total ozone column (TOC) from the direct-sun spectral measurements of a Bentham spectroradiometer located at Granada (Spain) is presented in this paper. The method relies on the differential absorption technique using two pairs of direct irradiance at adjacent wavelengths between 305 and 340 nm. The extraterrestrial constant was determined from the extrapolation to zero air mass of each wavelength pair (Langley plot method). We checked the strong influence of the cloud cover on the Bentham TOC measurements using simultaneous sky images taken with an all-sky camera. Thus, reliable TOC data are exclusively obtained during cloud-free conditions or partly cloudy conditions without the solar disk obstructed. In this work, the hourly TOC averages retrieved by the Bentham instrument with a standard deviation smaller than 3% (~ 10 Dobson Unit) are selected as high-quality TOC data. The analysis of the diurnal TOC variations during cloud-free days in late spring and summer showed different TOC values between the morning and afternoon periods. Thus, while the mornings exhibit an almost stable pattern, the afternoons display a monotonic TOC increase which could be partially related to photochemical processes in the lower troposphere associated with the formation of surface ozone. Finally, the Bentham TOC measurements were compared against the satellite data derived from three satellite instruments: OMI, GOME and SCIAMACHY. The mean absolute values of the relative differences between satellite and ground-based data were smaller than 3%, highlighting the high reliability of the retrieval method proposed in this paper to derive TOC data. ; This work was partially supported by the Andalusian Regional Government through projects P08-RNM-3568 and P10-RNM-6299, the Ministerio de Ciencia e Innovación through projects CGL2008-05939-C03-02/CLI, CGL2008-05939-C03-03/CLI, CGL2010-18782, CGL-2011-2992-1-C02-01 and CSD2007-00067, and by the European Union through the ACTRIS project (EU INFRA-2010-1.1.16–262254).

Early daily actinometric and cloud cover data from C aceres (SW of Spain) were recovered for the period 1913–1920. The task of retrieving and digitising early actinometric data series turn out highly required due to the lack of solar radiation data throughout the first half of twentieth century. Firstly, the Arago actinometer and the procedure employed to record the actinometric data were described in detail. Additionally, in spite of being a short series, trends from recovered actinometric data were analysed. A negative trend of (0.16 ± 0.03) C/year was obtained for all-sky conditions, reaching a marked value of (0.26 ± 0.04) C/year when cloud-free days were selected in the analysis. Both trends were statistically significant at the 95% confidence level. The Katmai eruption in June 1912 likely caused anomalous low actinometric records in 1913 and 1914. These results suggest a decrease of solar radiation in C aceres during the second decade of the twentieth century which is in accordance with the final stage of the long-term negative trend in solar radiation data observed at several European sites from late nineteenth century to the beginning of the twentieth century ('early dimming'). ; This work was partly funded by FEDER-Junta de Extremadura [Research Group Grant GR15137 and project IB16127] and from the Ministerio de Econom ıa y Competitividad of the Spanish Government [CGL2017- 87917-P].

Este trabajo tiene por objetivo estudiar la relación entre la producción de los documentos indexados del área de ciencias ambientales en la base de datos de SCOPUS y los países mejor evaluados dentro del Índice de Desempeño Ambiental (EPI). Para realizarlo, se analizan de forma bibliométrica los tres primeros lugares del EPI de los años 2014, 2016 y 2018, y tres países latinoamericanos, Brasil, Costa Rica y México. Entre los análisis desarrollados se encuentran: una categorización temática utilizando las palabras clave de la producción de ciencias ambientales valiéndose de los ejes del EPI como variable de identificación, comparación estadística respecto a la producción científica de cada país y el tipo de acceso de la misma. Se encontró que los países con una gobernanza fuerte (países mejor evaluados dentro del índice) no guardan relación con una mayor producción de publicaciones de ciencias ambientales.

This work was supported by the Spanish Ministry of Economy and Competitiveness through project CGL2014-56255-C2. Support from the Junta de Extremadura (Research Group Grant GR15137) is gratefully acknowledged. Work at the Universidad de Valladolid is supported by project CMT2015-66742-R. Work at the Universidad de Granada was supported by the Andalusia Regional Government (Project P12-RNM-2409) and the Spanish Ministry of Economy and Competitiveness and FEDER funds under the projects CGL2016-81092-R and "Juan de la Cierva-Formación" program (FJCI-2014-22052). ; In this work, water vapor radiative effect (WVRE) is studied by means of the Santa Barbara's Disort Radiative Transfer (SBDART) model, fed with integrated water vapor (IWV) data from 20 ground-based GPS stations in Spain. Only IWV data recorded during cloud-free days (selected using daily insolation data) were used in this study. Typically, for SZA = 60.0 ± 0.5° WVRE values are around − 82 and − 66 Wm−2 (first and third quartile), although it can reach up − 100 Wm−2 or decrease to − 39 Wm−2. A power dependence of WVRE on IWV and cosine of solar zenith angle (SZA) was found by an empirical fit. This relation is used to determine the water vapor radiative efficiency (WVEFF = ∂WVRE/∂IWV). Obtained WVEFF values range from − 9 and 0 Wm−2 mm−1 (− 2.2 and 0% mm−1 in relative terms). It is observed that WVEFF decreases as IWV increases, but also as SZA increases. On the other hand, when relative WVEFF is calculated from normalized WVRE, an increase of SZA results in an increase of relative WVEFF. Heating rates were also calculated, ranging from 0.2 Kday−1 to 1.7 Kday−1. WVRE was also calculated at top of atmosphere, where values ranged from 4 Wm−2 to 37 Wm−2

The daily (24 h) averages of the aerosol radiative forcing (ARF) at the surface and the top of the atmosphere (TOA) were calculated during desert dust events over Granada (southeastern Spain) from 2005 to 2010. A radiative transfer model (SBDART) was utilized to simulate the solar irradiance values (0.31–2.8 μm) at the surface and TOA, using as input aerosol properties retrieved from CIMEL sun photometer measurements via an inversion methodology that uses the sky radiance measurements in principal plane configuration and a spheroid particle shape approximation. This inversion methodology was checked by means of simulated data from aerosol models, and the derived aerosol properties were satisfactorily compared against well-known AERONET products. Good agreement was found over a common spectral interval (0.2–4.0 μm) between the simulated SBDART global irradiances at surface and those provided by AERONET. In addition, simulated SBDART solar global irradiances at the surface have been successfully validated against CM-11 pyranometer measurements. The comparison indicates that the radiative transfer model slightly overestimates (mean bias of 3%) the experimental solar global irradiance. These results show that the aerosol optical properties used to estimate ARF represent appropriately the aerosol properties observed during desert dust outbreak over the study area. The ARF mean monthly values computed during desert dust events ranged from −13 ± 8 W m−2 to −34 ± 15 W m−2 at surface, from −4 ± 3 W m−2 to −13 ± 7 W m−2 at TOA and from +6 ± 4 to +21 ± 12 W m−2 in the atmosphere. We have checked if the differences found in aerosol optical properties among desert dust sectors translate to differences in ARF. The mean ARF at surface (TOA) were −20 ± 12 (−5 ± 5) W m−2, −21 ± 9 (−7 ± 5) W m−2 and −18 ± 9 (−6 ± 5) W m−2 for sector A (northern Morocco; northwestern Algeria), sector B (western Sahara, northwestern Mauritania and southwestern Algeria), and sector C (eastern Algeria, Tunisia), respectively. The Kolmogorov-Smirnov statistical test revealed that daily {ARF} values at TOA for sector A were significantly different from the other two sectors, likely as a result of the lower values of single scattering albedo obtained for sector A. The mean values of aerosol radiative forcing efficiency at surface (TOA) were −74 ± 12 W m−2 (−17 ± 7 W m−2) for sector A, −70 ± 14 W m−2 (−20 ± 9 W m−2) for sector B, and −65 ± 16 W m−2 (−22 ± 10 W m−2) for sector C, and thus comparable between the three sectors in all seasons. ; This work was supported by the Andalusia Regional Government through projects P08-RNM-3568 and P10-RNM-6299, by the Spanish Ministry of Science and Technology through projects CGL2010-18782, CSD2007-00067 and CGL2011-13580-E/CLI; and by EU through ACTRIS project (EU INFRA-2010-1.1.16-262254). The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Barcelona Supercomputing Center. ALFA database computation was partly supported by RES (Spanish Supercomputation Network) computing resources (projects AECT-2009-1-0012, AECT-2011-3-0016).

This is the peer reviewed version of the following article: Antón, M.; et al. Sensitivity of UV Erythemal Radiation to Total Ozone Changes under Different Sky Conditions: Results for Granada, Spain. Photochemistry and Photobiology, 92(1): 215-219 (2016), which has been published in final form at http://dx.doi.org/10.1111/php.12539 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving ; This paper focuses on the analysis of the sensitivity of UV erythemal radiation (UVER) to variations of the total ozone column (TOC) under different sky conditions at Granada (southeastern Spain). The sensitivity is studied both in relative terms by means of the Radiation Amplification Factor (RAF) and in absolute terms using the Ozone Efficiency (OE). These two variables are determined for diverse sky conditions characterized by the cloud cover information given by a sky camera (in oktas) and the cloud optical depth (COD) estimated from global solar radiation measurements. As expected, in absolute terms, the TOC variations cause substantially smaller UVER changes during completely overcast situations than during cloud-free cases. For instance, the OE (SZA=30º, TOC=290 DU) decreases from 0.68 mW/m2 per unit of TOC (0 oktas) to 0.50 mW/m2 per unit of TOC (8 oktas). However, the opposite is observed when the analysis is performed in relative terms. Thus, the RAF (determined for SZA cases below 80º) increases from 1.1 for cloud-free cases (0 oktas) to 1.4 for completely overcast situations (8 oktas). This opposite behavior is also found when both RAF and OE are analyzed as functions of COD. Thus, while the OE strongly decreases with increasing COD, the RAF increases as COD increases. ; European Commission Horizon 2020 Research and Innovation Framework Programme through ACTRIS 2 project (H2020-INFRAIA-2014-2015-654109). ; Spanish Ministry of Economy and Competitiveness through projects CGL2011-29921-C02-01, CGL2013-45410-R, CGL2014-56255-C2-1-R. ; Andalusia Regional Government through projects P10-RNM-6299 and P12-RNM-2409.

This paper focuses on the assessment of atmospheric aerosol optical properties at the surface and in atmospheric column during both desert dust and dust-free conditions over Granada, South-eastern Iberian Peninsula. Indeed, the spectral dependence of aerosol absorption and scattering properties are analyzed in detail. The analyzed period ranges from June 2008 to December 2010. On dusty days, the mean scattering Angström exponent value obtained in the atmospheric column (SAEcol) (0.5±0.3) was lower than the observed at the surface level (SAEis) (1.3±0.6), indicating higher contribution of coarse particles at high atmospheric level than at ground level during the analyzed dust events. In addition, it is noticed that the absorption Angström exponent in the atmospheric column (AAEcol) with mean value of 1.5±0.2 and at the surface (AAEis) with mean value of 1.3±0.2 obtained during dusty situations are indicative of mixture of desert dust and black carbon particles as dominant absorbers both in the atmospheric column and at the surface during dust intrusions over Granada. On the other hand, a non-parametric test (Kolmogorov-Smirnov) revealed that no significant statistical difference was found for AAEis between desert dust and free-dust conditions. This result may be due to the important contribution of urban absorbing aerosol (e.g. Black carbon) at ground level in the study location. Therefore, these parameters (AAEcol and AAEis) are not very useful to detect desert dust events without the use of other information (e.g., aerosol size) over urban area like Granada.A dust extreme event was analyzed in order to retrieve optical parameters during situation dominated by desert dust. The values of SAEcol and SAEis obtained during this extreme event were in agreement with the values showed above for the period 2008-2010, although the differences between dust-free and dust conditions are more noticeable in this special event Aerosol scattering and absorption Angström exponent as indicators of dust and dust-free days over Granada (Spain). ; This work was supported by the Andalusia Regional Government through projects P12-RNM-2409 and P10-RNM-6299, by the Spanish Ministry of Science and Technology through projects CGL2010-18782, CSD2007-00067, CGL2011-29921-C02-01 and CGL2011-13580-E/CLI. ; Manuel Antón thanks the Ministerio de Ciencia e Innovación and Fondo Social Europeo for the award of a postdoctoral grant (Ramón y Cajal). ; CIMEL Calibration was performed at the AERONET-EUROPE calibration center, supported by ACTRIS (European Union Seventh Framework Program (FP7/2007-2013) under grant agreement no. 262254.

This paper proposes a method to obtain spectral sky radiances, at three wavelengths (464, 534 and 626 nm), from hemispherical sky images. Images are registered with the All-Sky Imager installed at the Andalusian Center for Environmental Research (CEAMA) in Granada (Spain). The methodology followed in this work for the absolute calibration in radiance of this instrument is based on the comparison of its output measurements with modelled sky radiances derived from the LibRadtran/UVSPEC radiative transfer code under cloud-free conditions. Previously, in order to check the goodness of the simulated radiances, these are compared with experimental values recorded by a CIMEL sunphotometer. In general, modelled radiances are in agreement with experimental data, showing mean differences lower than 20% except for the pixels located next to the Sun position that show larger errors. The relationship between the output signal of the All-Sky Imager and the modelled sky radiances provides a calibration matrix for each image. The variability of the matrix coefficients is analyzed, showing no significant changes along a period of 5 months. Therefore, a unique calibration matrix per channel is obtained for all selected images (a total of 705 images per channel). Camera radiances are compared with CIMEL radiances, finding mean absolute differences between 2% and 15% except for pixels near to the Sun and high scattering angles. We apply these calibration matrices to three images in order to study the sky radiance distributions for three different sky conditions: cloudless, overcast and partially cloudy. Horizon brightening under cloudless conditions has been observed together with the enhancement effect of individual clouds on sky radiance. ; The authors gratefully acknowledge the financial support extended by the Spanish Innovation and Science Ministry for the projects: CGL2011-25363 and CGL2010-12140E. Roberto Román thanks Valladolid University for the support to research short stays and for the PIF-UVa grants for PhD students. This work was also partially supported by the Andalusian Regional Government through projects P08-RNM-3568 and P10-RNM-6299, the Spanish Ministry of Science and Technology through projects CGL2010-18782 and CSD2007-00067, and by the European Union through ACTRIS project (EU INFRA- 2010-1.1.16-262254).