Javier Almorox

The Chemical Composition of Precipitation in Madrid

The present study examines the chemical characteristics of first-fraction precipitation samples collected over a period of one year in Madrid, and patterns of temporal and spatial variation observed in their composition. One hundred and sixty-four samples of wet precipitation collected on an event basis were analysed for anions, cations, pH and electrical conductivity. Precipitation in Madrid was neutral, with only 3% of samples showing pH < 5.6. Dominant ions were calcium andsulphates. Calcium was the principal neutralizing agent, explaining 64% of all nitrates and sulphates. The marine influence did not appear to be relevant, while the soil seemed to play an important role in the composition of precipitation. Precipitation chemistry displayed seasonal differences, with higher concentrations of sulphates and chloride in autumn and winter and of calcium and sodium in the summer. There was an inverse relationship between concentrations and sample volumes; while the correlation between concentrations and the time elapsedsince the last rain event was positive, though poor for normalized concentrations. Four variables (sample volume, days elapsed since the last rain event, maximum wind gust direction and season) explained to a large extent (more than 90% for some sampling stations) the variability of certain chemical variables.

Dynamics of pruning waste and spent horse litter co-composting as determined by chemical parameters

Co-composting of pruning waste and horse manure was monitored by different parameters. A windrow composting pile, having the dimensions 2.5m (height) x 30m (length) was established. The maturation of pruning waste and horse manure compost was accompanied by a decline in NH(4)(+)-N concentration, water soluble C and an increase in NO(3)(-)-N content. Organic matter (OM) content during composting followed a first-order kinetic equation. This result was in agreement with the microbiological activity measured by the CO(2) respiration during the process. The correlation at a high level of probability found between the OM loss and CO(2) evolution showed that both parameters could be used to indicate the degree of OM degradation that is the maturity and stability phases of the compost studied. Humification parameters data from the organic matter fractionation did not show a clear tendency during the composting time, suggesting that these parameters are not suitable for evaluating the dynamics of the process.

Worldwide assessment of the Penman–Monteith temperature approach for the estimation of monthly reference evapotranspiration

When not all the meteorological data needed for estimating reference evapotranspiration ETo are available, a Penman–Monteith temperature (PMT) equation can be adopted using only measured maximum and minimum air temperature data. The performance of the PMT method is evaluated and compared with the Hargreaves–Samani (HS) equation using the measured long-term monthly data of the FAO global climatic dataset New LocClim. The objective is to evaluate the quality of the PMT method for different climates as represented by the Köppen classification calculated on a monthly time scale. Estimated PMT and HS values are compared with FAO-56 Penman–Monteith ETo values through several statistical performance indices. For the full dataset, the approximated PMT expressions using air temperature alone produce better results than the uncalibrated HS method, and the performance of the PMT method is even more improved adopting corrections depending on the climate class for the estimation of the solar radiation, especially in the tropical climate class.

Assessment of surface solar irradiance retrieved by CERES

ABSTRACT This study compared and evaluated the monthly global solar radiation generated by Clouds and the Earth’s Radiant Energy System (CERES) with the surface radiation registered in 232 meteorological stations located in whole Spain, for the period of July 2006–July 2015. Results showed strong correlations between CERES and registered data with R2 values greater than 0.96, for all stations considered. When the temporal evolution of recorded and provided by CERES solar radiation was analysed, a systematic overestimation by CERES was detected from July 2011, although the shapes of both curves were respected in the whole period. This finding led us to propose a linear adjustment model since July 2011. After applying the developed model to rescale CERES data for the whole period, an improvement in solar radiation fit was observed. Our finding offers an insight into error patterns of CERES solar radiation, since July 2011, and proposes a model for improving accuracy allowing therefore a reliable use of this product. Moreover, our study on radiation data of Spain provides a case example for worldwide validation.