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  • 1
    Electronic Resource
    Electronic Resource
    Estimating solar ultraviolet irradiance (290/385 nm) by means of the spectral parametric models: SPCTRAL2 and SMARTS2 (2000)
    Springer
    Annales geophysicae 18 (2000), S. 1382-1389 
    Details
    ISSN: 0992-7689
    Keywords: Atmospheric composition and structure (transmission and scattering of radiation) ; Meteorology and atmospheric dynamics (radiative process)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Since the discovery of the ozone depletion in Antarctic and the globally declining trend of stratospheric ozone concentration, public and scientific concern has been raised in the last decades. A very important consequence of this fact is the increased broadband and spectral UV radiation in the environment and the biological effects and heath risks that may take place in the near future. The absence of widespread measurements of this radiometric flux has lead to the development and use of alternative estimation procedures such as the parametric approaches. Parametric models compute the radiant energy using available atmospheric parameters. Some parametric models compute the global solar irradiance at surface level by addition of its direct beam and diffuse components. In the present work, we have developed a comparison between two cloudless sky parametrization schemes. Both methods provide an estimation of the solar spectral irradiance that can be integrated spectrally within the limits of interest. For this test we have used data recorded in a radiometric station located at Granada (37.180°N, 3.580°W, 660 m a.m.s.l.), an inland location. The database includes hourly values of the relevant variables covering the years 1994/95. The performance of the models has been tested in relation to their predictive capability of global solar irradiance in the UV range (290/385 nm). After our study, it appears that information concerning the aerosol radiative effects is fundamental in order to obtain a good estimation. The original version of SPCTRAL2 provides estimates of the experimental values with negligible mean bias deviation. This suggests not only the appropriateness of the model but also the convenience of the aerosol features fixed in it to Granada conditions. SMARTS2 model offers increased flexibility concerning the selection of different aerosol models included in the code and provides the best results when the selected models are those considered as urban. Although SMARTS2 provide slightly worse results, both models give estimates of solar ultraviolet irradiance with mean bias deviation below 5%, and root mean square deviation close to experimental errors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-000-1382-2
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  • 2
    Electronic Resource
    Electronic Resource
    Day-night differences in the effective emissivity from clear skies (1988)
    Springer
    Boundary layer meteorology 45 (1988), S. 93-101 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 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 basis. A deviation correction in terms of the hour of the day is proposed. This term takes into account the differences in the daily cycle of effective emissivity for different seasons, and provides estimates accurate to within the experimental errors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120817
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  • 3
    Electronic Resource
    Electronic Resource
    Estimation of hourly values of downward atmospheric radiation under cloudless skies during day- and night-time conditions (1993)
    Springer
    Theoretical and applied climatology 48 (1993), S. 127-131 
    Details
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Several atmospheric radiation models have been developed which provide methods for evaluating the effective emissivity of the atmosphere. Most of these methods are derived for night-time data utilizing local empirical coefficients. There are several, however, which are thought to be more universal in their predictive ability and some of these were tested on a data set registered in Granada from 1983 to 1985, inclusive. The models evaluated in this study are the Brutsaert model, the Berdahl and Martin model and the method proposed by Idso; in the first two cases the original coefficients were used. All the equations showed a good behaviour for night-time data but consistently overestimated day-time measured radiation. These deviations are explained in terms of day-night differences in the effective emissivity regime due to the differing vertical structure of the atmosphere during day and night. An empirical correction term for these differences improves the estimates of these models. The Idso model with a reduction in its independent term provided the best adjustment. Nevertheless, the Berdahl and Martin model with the original coefficients and the day-night correction term provided good results too, deviations being within the experimental error, indicating the universality of its coefficients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00864919
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  • 4
    Electronic Resource
    Electronic Resource
    On the estimation of long-wave radiation flux from clear skies (1987)
    Springer
    Theoretical and applied climatology 38 (1987), S. 37-42 
    Details
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Zusammenfassung Es werden Daten der langwelligen atmosphärischen Strahlung bei Barcelona herangezogen, um verschiedene Methoden zur Bestimmung dieser Komponente der Strahlungsbilanz bei klarem Himmel zu vergleichen. Dazu werden zwei unterschiedliche Formeltypen, die analytischen nach Swinbank und Brutsaert (1 und 2) und empirische nach Brunt, Idso und Jackson sowie Idso (1 und 2) benützt. Von diesen Methoden wurden die meisten für einen bestimmten Ort entwickelt und verwenden daher lokale empirische Koeffizienten. Allerdings gibt es einige, die als allgemein verwendbar angesehen werden. Für beide Typen der Abschätzung ergeben sich für Lufttemperaturen über 0°C im Hüttenniveau ähnliche Werte. Bei Lufttemperaturen unter 0°C zeigen sich jedoch einige Unterschiede zwischen den beobachteten und geschätzten Werten der langwelligen atmosphärischen Strahlung. Das legt nahe, die Koeffizienten sowohl für die analytischen als auch die empirischen Formeln anzupassen. Leider war das auf Grund des geringen Datenmaterials bei Temperaturen unter 0°C innerhalb dieser Untersuchung nicht möglich.
    Notes: Summary 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 Idso 1 and 2 were used in the test. Most of these methods are derived for a particular location and utilize local empirical coefficients. However, there are several which have been considered more universal. Estimates by the two methods give approximately the same value when the screen level air temperature is above 0°C. In addition, the test for temperatures below 0°C shows several discrepancies between the observed and estimated values of long-wave atmospheric radiation. This fact suggests that modifications may be needed for both analytical and empirical formulae. However, since we have few measurements in the temperature regime below 0°C, this statement cannot be justified as a conclusion of this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00866251
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal radiation from cloudless skies in Granada (1986)
    Springer
    Theoretical and applied climatology 37 (1986), S. 84-89 
    Details
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Zusammenfassung Die von Mai bis November 1983 in Granada gesammelten Daten über Wärmestrahlung bei klarem Himmel wurden dazu verwendet, um einen detaillierten Vergleich zwischen gemessenen und errechneten Werten der langwelligen Strahlung aus verschiedenen analytischen und empirischen Gleichungen durchzuführen. Das Ziel dieser Arbeit ist es, die Anwendbarkeit dieser Gleichungen auf die Verhältnisse in Granada zu überprüfen. Die gewonnenen Ergebnisse sind für alle diese Gleichungen ganz zufriedenstellend. Idsos Formel überschätzt jedoch deutlich unsere experimentellen Ergebnisse, möglicherweise als Folge der unterschiedlichen atmosphärischen Staubbedingungen in unserem Testgebiet und dem Standort, für den die Gleichung ursprünglich abgeleitet wurde. Eine Reduktion des unabhängigen Koeffizienten, in Übereinstimmung mit früheren Ergebnissen anderer Autoren, bietet eine bessere Anpassung an unseren Datensatz und zeigt deutlich die klimatologische Abhängigkeit der Konstanten in Schätzungsgleichungen.
    Notes: Summary 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 results obtained for all the equations are quite satisfactory. Nevertheless, Idso's formula significantly overestimates our experimental results, probably as a consequence of the differences in atmospheric dust conditions between our test area and the location for which that equation was originally derived. A reduction in the independent coefficient, in accordance with previous results of other authors, provides a better fit to our data set and clearly shows the climatological dependence of the constants in the estimation equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00866107
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  • 6
    Electronic Resource
    Electronic Resource
    The European Community Cloudless Sky Radiance Model. An Evaluation by Means of the Skyscan’834 Data Set (1999)
    Springer
    Theoretical and applied climatology 63 (1999), S. 141-147 
    Details
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Having in mind the high complexity of the sky radiance distribution, the Commission of the European Communities, in the frame of the Solar Energy R&D in the European Community Programme, developed among other related fields of research a clear sky radiance model. This model, the so-called EC-Model, was intended for the estimation of the diffuse irradiance falling on an inclined surface by integration of the sky radiance field. It represents a progress development over its predecessor, the Berlin model, and takes into account all the scientific knowledge about this topic, lying heavily on the principles of the Liebelt formulation and the work of Steven and Unsworth on the observed relative radiance distribution. The European Solar Radiation Atlas was in part prepared by the adoption of the EC-Model and could not take into account Valko’s new results about sky radiance distributions, because of time coincidence and that only previous results were ready at the time it was published. In this work, we focus on the EC-Model behaviour, against experimental sky radiance data from Toronto, Canada. The SKYSCAN’834 Data Set is a well-known database, which we have used in order to investigate the EC-Model behaviour both under its original formulation (the one that has been used in the development of the Atlas) and under the modified version suggested by Valko’s results. Even though we are considering data from outside Europe, the results of this test let us establish the model limitations and the modifications that should be done to it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007040050099
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of Cloudless Sky Parameterizations of Solar Irradianceat Various Spanish Midlatitude Locations (2000)
    Springer
    Theoretical and applied climatology 66 (2000), S. 81-93 
    Details
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary We have developed a comparison among several cloudless sky parameterization schemes of the solar irradiance incoming at surface level. The data set was recorded at various Spanish mid-latitude radiometric stations, covering different climatic regimes. It consists of hourly values of the relevant quantities covering periods greater than one year at each radiometric station. Diffuse irradiance data have been corrected for shadowband effect using a model developed by the authors and successfully tested at various radiometric stations. At a first stage, the models were run using all the available local information. After that, we have run the models that present the better performance and, considering that under some circumstances not all the input parameters are available replacing some parameters by their monthly values. As the study reveals, the Gueymard and the Iqbal C model, which require the availability of appropriate information on aerosols, perform best. The influence of precipitable water is of second order thus allowing for the use of estimates based on monthly mean values obtained from climatological records. On the other hand, the study performed on the influence of solar elevation angle on models performance reveals that the worst results correspond to lower solar elevations. This could be a result of limitations in the transmittance parameterization for these elevations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007040070034
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  • 8
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    Role of spheroids particles on closure studies for aerosol microphysical-optical properties (2015)
    Wiley
    Details
    Publication Date: 2015-03-28
    Description: ABSTRACT A study has been carried out to assess the discrepancies between computed and observed aerosol scattering and backscattering properties in the atmosphere. The goals were: (1) to analyze the uncertainty associated with computed optical properties when spherical and spheroid approximations are used and (2) to estimate nephelometry errors due to angular truncation and non-Lambertian illumination of the light source in terms of size range, particle shape and aerosol chemical compounds. Mie and T-matrix theories were used for computing light optical properties for spherical and spheroid particles, respectively, from observed particle size distributions. The scattering coefficient of the fine mode was not much influenced by the particle shape. However, computed backscattering values underestimated the observed values by ~15%. For the coarse mode the spheroidal approximation yields better results than that for spherical particles, especially for backscattering properties. Even after applying the spheroidal approximation, computed scattering and backscattering values within the coarse mode underestimated the observed values by ~49% and ~11%, respectively. The angular correction most widely used to correct the nephelometer data was discussed to explore its uncertainty. In the case of the scattering properties within the coarse mode the change of the computed optical parameter is ~ +8% and for the scattering and backscattering values within the fine mode it is lower than ~ ±4% for spherical and spheroid particles. Additionally, if the spheroid particles are used to evaluate the aerosol optical properties, the correction must be reconsidered with the aim of reducing the uncertainty found for scattering within the coarse mode. This is recommended for sites with desert dust influence, then the deviation of the computed scattering can be up to 13%.
    Print ISSN: 0035-9009
    Electronic ISSN: 1477-870X
    Topics: Geography , Physics
    Published by Wiley
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  • 9
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    Spatio-temporal monitoring by ground-based and air- and space-borne lidars of a moderate Saharan dust event affecting southern Europe in June 2013 in the framework of the ADRIMED/ChArMEx campaign (2017)
    Springer
    Details
    Publication Date: 2017-01-11
    Print ISSN: 1873-9318
    Electronic ISSN: 1873-9326
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Springer
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  • 10
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    A model for climatological estimations of global, diffuse, and direct solar radiation on a horizontal surface (1989)
    Elsevier
    Details
    Publication Date: 1989-01-01
    Print ISSN: 0038-092X
    Electronic ISSN: 1471-1257
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Published by Elsevier
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