Juan I Jimenez

Juan I Jimenez
University of Granada | UGR · Department of Applied Physics

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20
Publications
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431
Citations

Publications

Publications (20)
Article
Full-text available
A model for the urban canyon is formulated for meteorologicalconditions of weak winds at night time. Thermal radiation, conductivity and convection are simulated by means of the Monte Carlo method. These are the main physical processesof energy transfer that give rise to the characteristic temperaturedistribution in these systems. The model has bee...
Article
In this study we examine the Urban Heat Island (UHI) of Granada. First, we perform a study of the evolution of the recorded temperatures at a meteorological station over the last century. In this record, the minimum temperatures increase while the maximum temperatures decrease. We also compare both rural and urban temperature records, obtaining the...
Article
In this work we simulate, by a Monte Carlo method, the balance of longwave radiation within different urban structures. The experiment consists in simulating the foton traces, and then to evaluate the percentage of lost longwave radiation. Also we calculate the decrease in temperature for each grid comparing different structures. As a result we obt...
Article
Monthly mean values of daily and hourly global solar irradiation at eight stations in Spain are analysed on the basis of the similarity between the shape of extraterrestrial irradiance during the day and the Gaussian curve. This shape is found to be the same on the Earth's surface after attenuation through the atmosphere whenever the averaged-out p...
Article
A simple model based on the intensity of direct and diffuse radiation expressed as fractions of the intensity of the extraterrestrial radiation has been developed. Using these expressions and assuming a random distribution of bright sunshine hours with not too wide a variation in the transmission coefficient values, a number of equations for estima...
Article
Full-text available
A study of the effective emissivity from clear skies shows significant differences between night- and day-time behaviours. These differences seem to be related to the different conditions aloft for the day and night periods. For this reason, estimation formulae that rely only on surface parameters do not provide accurate estimates on an hourly basi...
Article
Full-text available
Anomalies in the performance of the Eppley pyrgeometer with a silicon dome during daytime measurements are discussed. The problems are mainly related to the solar heating of the dome which causes nearly instantaneous fluctuations in the longwave irradiance measured by the pyrgeometer during cloudless days. The solar heating effect of the dome is ev...
Article
Full-text available
Data from measurements of long-wave radiation at Barcelona were used to test the validity of several methods for computing this component of the radiation balance in clear sky conditions. Two types of formulae, the analytically derived formulae of Swinbank and Brutsaert 1 and 2 and the empirically obtained formulae of Brunt, Idso and Jackson and Id...
Article
Data on thermal radiation from clear skies obtained at Granada from May to November 1983 were utilized to carry out a detailed comparison between measured and calculated values of longwave radiation with several analytical and empirical equations. The goal of this work is to check the aplicability of these equations to Granada conditions. The resul...
Article
Measurements of the global and diffuse radiation flux at various tilt and azimuth angles were made on clear days to determine the increase or decrease of captured energy when the surface is not horizontal. The data obtained by a pyranometer equatorially mounted on a modified theodolite system were compared with those obtained by Temps and Coulson (...
Article
Data from several experiments on the modification of the climate in a glasshouse are presented to test their influence on the possibility of using the glasshouse in a hot summer.The glasshouse is an aluminium structure glazed with light-diffusing glass and is orientated N-S. It is equipped with a cooling system consisting of two ventilators and a w...
Article
A calibration technique for an infrared remote sensing system on board a research aircraft is described. The equipment includes an infrared line scanner (IRLS) operating in the 8 to 14 micrometer range, a Barness precision radiometer thermometer (PRT), and Hasselblad cameras with infrared filters. For the sea data, a marine unit with in situ temper...

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