AbstractIn this paper we compare cloud cover coefficient values derived from satellite images by using three different algorithms with cloud cover fraction obtained by automatic technique using a CCD sensor set on a ground platform. The main goal is to optimize the results obtained by each of the three satellite techniques when applied as input data for radiative transfer models. The satellite techniques are applied to generate clear and overcast composite images on the visible spectra (0.52–0.75pm), and the cloud cover coefficients are obtained from linear interpolation between clear and overcast conditions. The ground technique uses a CCD sensor adapted to a fisheye lens to derive cloud cover fraction in the visible range (0.4–0.7gm). We compared these techniques using data collected at the BSRN station of Floiianópolis (27° 28′S, 48° 29′W). The study encompasses the period from January/2002 to March/2002. The radiative transfer model has underestimated the incident global solar radiation by 25–32% when derived from cloud cover fractions obtained by the CCD sensor. When supplied with the cloud cover information derived from the satellite techniques the bias decrease to 3–7%. The reason for the underestimation is attributed to the fact that cloud cover fraction derived from the ground data does not bear information on cloud optical thickness.


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    Titel :

    Comparative study of satellite and ground techniques for cloud cover determination


    Beteiligte:
    Martins, F.R. (Autor:in) / Souza, M.P. (Autor:in) / Pereira, E.B. (Autor:in)

    Erschienen in:

    Advances in Space Research ; 32 , 11 ; 2275-2280


    Erscheinungsdatum :

    2003-04-20


    Format / Umfang :

    6 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch