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In the context of global warming, it is a well-known fact that there is an increase in precipitation in middle latitudes. Convective phenomena have also been on the increase in the past few decades. It is gradually becoming more difficult to characterize climatic trends in middle latitudes. Data show that there may be different results depending on the study zones. Thus, it is interesting to study climatic changes in recent precipitation series, especially if we can have at our disposal a dense network of rainfall stations with reliable precipitation series.The analysis of precipitation series in 333 rainfall stations from 1961 to 1990 has revealed that summer precipitation shows a statistically significant trend in wide areas of Mainland Spain. In the months of July and August, the precipitation is exclusively convective. In those months, the precipitation increased in 20% of the southern areas, that is, in those areas where temperatures are on average higher. June and September present different trends showing a decrease in precipitation in 10% of the territory.

ABSTRACT: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.

In July 2012, an indoor/outdoor monitoring programme was undertaken in two university sports facilities: a fronton and a gymnasium. Comfort parameters (temperature, relative humidity, and CO 2 ), CO and total volatile organic compounds (TVOCs) were continuously monitored. Concentrations of NO 2 , carbonyl compounds and individual VOCs were obtained, after passive sampling, by spectrophotometry, high-performance liquid chromatography and gas chromatography with flame ionisation detection, respectively. Low volume samplers were used to collect particulate matter (PM 10 ). During the occupancy periods, the relative humidity values were within the comfort limits in both buildings, but frequent daytime temperatures over 30°C in the gymnasium make this indoor space rather uncomfortable. The minimum ventilation rates stipulated for acceptable indoor air quality were observed in both sports facilities. It was found that cleaning activities may have a large influence on the VOC levels. Acrolein was one of the most abundant carbonyl compounds, showing concentrations above the recommended limit. Formaldehyde was detected at levels lower than those commonly reported for other indoor environments. In the fronton, the PM 10 concentrations obtained during the occupancy periods ranged between 38 and 43 µg/m 3 . Much higher levels, from 154 to 198 µg/m 3 , were registered in the gymnasium. Weekend average values lower than 20 µg/m 3 were obtained in both sports facilities, which are comparable to the outdoor levels throughout the week. The high particle levels in the gym are mainly due to the climbing chalk and the constant process of resuspension.