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The temporal variation of aerosol size distribution in León, Spain, was analyzed with an optical spectrometer, in order to identify changes associated with the summer-autumn transition. For each hour and day of the week, we have studied the temporal variation of the particle number during the day. As the summer progresses, the total particle number increases from 1000 ± 600 in August to 1500 ± 1000 particles cm−3 in October, mainly due to more intense road traffic after the summer holidays and to the beginning of the new academic year in the study area in September. The particle number was higher on weekdays than on weekends in September and October. However, in August the values were similar, due to lower activity in the city, coinciding with the main holiday period. The aerosol size distributions were bimodal. In the fine mode, both the highest concentration (573 particles cm−3) and the lowest count median diameter (0.08 μm) were recorded in October. The contribution of particles from forest fires and Saharan dust intrusions had a negative impact on the air quality of the city during the summer. Considering the estimated respirable fraction in healthy adults (after the Standard ISO 7708:1995), on weekdays the highest values are obtained between 0600 and 1000 UTC (around 15 μg m−3) and in the afternoon, between 1700 and 2000 UTC (around 12 μg m−3), coinciding with the rush hour. [ABSTRACT FROM AUTHOR]

The variability of winter precipitation in the west of the Iberian Peninsula is strongly affected by the North Atlantic Oscillation (NAO). This study focuses on identifying the relationship that exists between precipitation registered in the city of León (in northwestern Spain), the NAO index and the associated weather type during the same period. In order to achieve this objective, the prevailing weather type has been calculated for each day in León from January 1948 to March 2009, using the objective Lamb Weather Types classification method. The most significant results appear in winter (from December to March). During these months an increase has been observed in the frequency of 'anticyclonic' weather type (A) (very dry), and a decrease in the 'cyclonic' (C), 'south-westerly' (SW) and 'westerly' (W) types (the three rainiest weather types). The positive trend in the NAO index could be the main cause of the decrease in the frequency of the three rainiest weather types (C, SW and W) and therefore, responsible for the relevant decline in winter precipitation observed in the city of León. The high correlation coefficients between the NAO index, the frequency of the three rainiest weather types and winter precipitation suggests an interesting method to forecast rainfall. Using a binary logistic regression model, a downscaling model for daily precipitation has been obtained based on the weather types and the NAO index. The daily results obtained for the winter months are good (TSS = 0.64) bearing in mind that only sea level pressure data were used in the logistic model. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The article analyzes the research on disdrometers based on published literature. It uses the Web of Science, published by Thomson Reuters, as the data base of bibliographic reference. It collects more than 300 articles which are analyzed according to several criteria including the countries with research using disdrometers, publication dates, bibliometric analysis of the more than 60 journals where these articles have been published.

Annual, seasonal and monthly rainfall trends from 1961 to 2006 period were analysed in this study by applying various statistical tools to data from 553 Spanish weather stations. The magnitude of the trends was derived from the slopes of the regression lines using the least squares method, while the statistical significance was determined using the non-parametric Mann-Kendall test. Geostatistical interpolation techniques were applied to generate rainfall trend surfaces. Combining classic trends tests and spatially interpolated precipitation permits the spatio-temporal visualization of detected trends. Updated trends reveal that rainfall is generally decreasing in January, February, March, April, and June. Around 61, 44 and 12% of the whole territory is evidencing significant negative trends in February, June and March, respectively. Significant precipitation decreases are also noted in more than 28% of Spain in summer and winter. On the contrary, rainfall is significantly increasing in October in more than 21% of Spain and areas mainly located in north-western areas. May, August, September and autumn also show significant positive trends in the period 1961-2006, although the percentages are lower than for negative trends. Finally, the annual precipitation is significantly decreasing in 11% of the territory. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Ambient PM10 and PM2.5 aerosols were monitored in Toulouse from March 2004 to February 2005 (Extensive Observed Period (EOP)) as part of the research project CAPITOUL (Canopy and Aerosol Particles Interaction in TOulouse Urban Layer). Concentrations of 8 major ions (Na+, NH4 +, K+, Mg+2, Ca+2, Cl−, NO3 −, SO4 2−), 15 metal elements (Al, Ba, Cd, Ce, Cr, Cu, Fe, La, Mn, Ni, Pb, Sr, Th, Ti, Zn), and carbonaceous aerosols [TC, POM and EC (total carbon, organic carbon and elemental carbon, respectively)] were measured in a total of 52 samples of each size. Inter-seasonal variations were analyzed. Weekly PM2.5 and PM10 total mass concentrations (major ions + carbon + metal elements) were 4.4–18.0 µg m−3 and 6.5–23.5 µg m−3, with an annual average concentration of 11.0 ± 3.6 µg m−3 and 13.2 ± 4.3 µg m−3, respectively. The highest concentration for sulfate was found in summer and fall, whereas the highest NO3 − concentration was observed in winter. This study is strengthened by Kruskal–Wallis and Mann–Whitney statistical tests. On average, carbonaceous species constitute between 49% and 75% of the monthly concentration registered, POM concentration always remaining higher (ratio more than 51%) than EC in both size ranges. The average OC/EC ratios were 2.70 ± 0.81 and 2.70 ± 0.60 for PM2.5 and PM10, respectively. Secondary organic carbon concentrations were significantly higher in the warmer seasons reaching in summer average ratios of 65.9% and 64.5% of the total OC concentration for PM2.5 and PM10, respectively. Secondary organic carbon was produced in the fine fraction of the aerosol. Metal elements analysis and enrichment factor calculations show that traffic emissions were the major influence on the chemical composition of the urban aerosol. A receptor modeling study was conducted using Principal Component Factor Analysis followed by multi-linear regression analysis in order to provide quantitative insights into the sources of specific chemical components in PM10. [ABSTRACT FROM AUTHOR]

Flexible radio resource management schemes are nowadays used within a wide range of systems. However, the optimal selection for their adaptation rate is still an open research issue. This paper presents an analytical approach to such problem, which consists in a combined analysis of the dynamics of the session-arrival process and the estimation of the mean traffic load from network measurements. From this study, it is concluded that both aspects pose an upper limit on the optimal system adaptation rate, being the most restrictive the one depending on the mean traffic load estimation. A specific procedure for deriving such limit on adaptation rate is provided. It is shown that the derived value directly depends on the mean service duration. The application of the whole analysis is illustrated with an example based on a set of measurements from a live network. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The present paper is an analysis of mean maximum and minimum temperatures carried out on monthly, seasonal and annual time-scales examining the data collected at 171 meteorological stations over a region in the North West of Spain (Castilla y León) for the period 1961–1997. Various statistical tools were used to detect and describe significant trends in these data. The magnitude of the trends was derived from the slopes of the regression lines using the least squares method, and the statistical significance was determined by means of the non-parametric Mann-Kendall test. The pattern obtained is quite similar for mean maximum and minimum temperatures with increases in all months of the year, and in the annual series. The seasonal series corresponding to winter and summer also followed this same pattern. Spring and autumn were found to be more irregular. Because maximum temperature increased at a higher rate than minimum temperature in this period, an increase in the annual diurnal temperature range (DTR) was observed. The correlation between the North Atlantic Oscillation (NAO) and the regional maximum and minimum temperatures and DTR series for the period 1961–1997 have also be studied in this paper. [ABSTRACT FROM AUTHOR]

The combination of several thermodynamic variables based upon the data provided by a radiosounding can be useful for the forecasting of thunderstorms. As a matter of fact, there are many indices that allow the establishment of a storm risk prediction once they have been gauged. The problem comes when not all indices lead to the same prediction. In these cases, it is necessary to establish one single function based on the information provided by all the variables employed, which should be able to determine a two-fold prediction: risk or no risk. This article presents a statistic model for the short tem prediction of thunderstorms in the region of León (Spain). To reach this aim 15 meteorological variables were selected. These variables were easy to handle by non-expert staff, and they allowed the characterisation of the preconvective environment early in the morning on thunderstorm days. The variables have been properly combined and gauged with the help of a dense network of meteorological observers. The result has led to the construction of a reliable model. The discriminant quadratic model has been easily applied to determine in an objective and binary way the risk/no risk for the occurrence of thunderstorms. [ABSTRACT FROM AUTHOR]

Proposes a statistical model for assessing barley and wheat crop damages caused by hailstorms in the northwestern region of Leon, Spain. Difficulties of simulated models; Method of data collection; Effect of hail size and crop maturity on damage loss; Comparison of damage resistance of wheat and barley.

This article presents a shadowing simulation model based on multiple-edge diffraction. Such model provides an appropriate tool for simulating shadowing in cases where over-obstacle diffraction is the main propagation mechanism. Results show that the model is in good agreement with literature in terms of its statistical parameters. Moreover, its capability for dealing with variations in antenna height makes it appropriate for simulating a wide range of wireless systems [ABSTRACT FROM PUBLISHER]

Residential dust is recognized as a major source of environmental contaminants, including polycyclic aromatic hydrocarbons (PAHs) and plasticizers, such as phthalic acid esters (PAEs). A sampling campaign was carried out to characterize the dust fraction of particulate matter with an aerodynamic diameter smaller than 10 µm (PM10), using an in situ resuspension chamber in three rooms (kitchen, living room, and bedroom) of four Spanish houses. Two samples per room were collected with, at least, a one-week interval. The PM10 samples were analyzed for their carbonaceous content by a thermo-optical technique and, after solvent extraction, for 20 PAHs, 8 PAEs and one non-phthalate plasticizer (DEHA) by gas chromatography-mass spectrometry. In general, higher dust loads were observed for parquet flooring as compared with tile. The highest dust loads were obtained for rugs. Total carbon accounted for 9.3 to 51 wt% of the PM10 mass. Plasticizer mass fractions varied from 5 µg g−1 to 17 mg g−1 PM10, whereas lower contributions were registered for PAHs (0.98 to 116 µg g−1). The plasticizer and PAH daily intakes for children and adults via dust ingestion were estimated to be three to four orders of magnitude higher than those via inhalation and dermal contact. The thoracic fraction of household dust was estimated to contribute to an excess of 7.2 to 14 per million people new cancer cases, which exceeds the acceptable risk of one per million. [ABSTRACT FROM AUTHOR]

A novel procedure based on the alternating projection method to adjust experimental shadowing cross-correlation (SCC) matrices is proposed. Given an SCC matrix derived from any experimental model, this procedure finds the nearest diagonalisable correlation matrix. This adjustment allows a proper simulation of shadowing samples, since it produces correlation matrices for which Cholesky factorisation is feasible. Simulation results using this procedure for three different SCC models are compared and discussed. [ABSTRACT FROM AUTHOR]

The number of particles and their size distributions were measured in a rural area, during the summer, using a PCASP-X. The aim was to study the influence of wildfires on particle size distributions. The comparative studies carried out reveal an average increase of around ten times in the number of particles in the fine mode, especially in sizes between 0.10 and 0.14 μm, where the increase is of nearly 20 times. An analysis carried out at three different points in time--before, during, and after the passing of the smoke plume from the wildfires--shows that the mean geometric diameter of the fine mode in the measurements affected by the fire is smaller than the one obtained in the measurements carried out immediately before and after (0.14 μm) and presents average values of 0.11 μm. [ABSTRACT FROM AUTHOR]

Since 1990 the Laboratory for Atmospheric Physics at the University of Leon has made use of a network of 250 hailpads spread over an areaof 1000 km2 in the province of Leon (north-western Spain). By the end of 1995, the network had detected 25 hailfalls of more than 15 km2 in area, registered on 13 different days duringthe summer months. The 25 hailfalls were precipitated over more than 300 separate hailpads, leaving nearly 40 000 measurable prints. Thesize of each hailstone, whose mass and kinetic energy were taken simply as a function of the diameter of the stone was calculated using the hailpad network. In this way, an estimate has been made of the total quantity of ice which fell in each hailfall (circa 19 000 metric tons on average, although a figure ten times this was calculated for one particular hailstorm). The spatial evolution of the physical variables of the hail, determined from each pad, has also been graphicallyrepresented. In addition, the distribution of hailstone sizes has been analysed, and the characteristic distribution parameters calculated. Although exponential distribution is often used, the Kolmogorov-Smirnov test of goodness-of-fit shows a better fit for gamma distribution. The information provided by these parameters has been analyzed for both distributions, in relation to some specific variables associated with hail. There is a good correlation between total energy and mass precipitated, but the quantity of hail per unit area correlates with the total energy or mass of the precipitation only through the area affected. The size distribution parameters only show good correlations with the maximum hailstone size recorded. [ABSTRACT FROM AUTHOR]