@Article{Souza-EcherPereBinsAndr:2006:SiMeAs,
               author = "Souza-Echer, M. P. and Pereira, Enio Bueno and Bins, Leonardo 
                         Sant' Anna and Andrade, M. A. R.",
          affiliation = "Instituto Nacional de Pesquisas Espaciais (INPE), Centro de 
                         Previs{\~a}o de Tempo e Estudos Clim{\'a}ticos (CPTEC) and 
                         Instituto Nacional de Pesquisas Espaciais (INPE), Centro de 
                         Previs{\~a}o de Tempo e Estudos Clim{\'a}ticos (CPTEC) and 
                         Instituto Nacional de Pesquisas Espaciais (INPE), Centro de 
                         Previs{\~a}o de Tempo e Estudos Clim{\'a}ticos (CPTEC) and 
                         Instituto Nacional de Pesquisas Espaciais (INPE), Centro de 
                         Previs{\~a}o de Tempo e Estudos Clim{\'a}ticos (CPTEC)",
                title = "A simple method for the assesment of the cloud cover state in high 
                         latitude regions by a ground based Ddgital camera",
              journal = "Journal of Atmospheric and Oceanic Technology",
                 year = "2006",
               volume = "23",
               number = "3",
                pages = "437--447",
                month = "Mar.",
             keywords = "high-latitude, digital camera, geostationary operational 
                         environmental satellite, meteorological satellite, national 
                         oceanic, nimbus.",
             abstract = "This work describes the development of a simple method of field 
                         estimating the sky cloud coverage percentage for several 
                         applications at the Brazilian Antartic Station, Ferraz (62º 05S, 
                         58º 23.5W). The database of this method was acquired by a digital 
                         color camera in the visible range of the spectrum. A new algorithm 
                         was developed to classify each pixel according to a criteria 
                         decision process. The information on the pixel contamination by 
                         clouds was obtained from the saturation component of the 
                         intensity, hue, and saturation space (IHS). For simplicity, the 
                         images were acquired with a limited field of view of 36º pointing 
                         to the cameras zenith to prevent direct sunlight from reaching the 
                         internal charge-coupled device (CCD) on the camera. For a 
                         priori-classified clear-sky images, the accuracy of the method was 
                         superior to 94%. For overcast-sky conditions, the corresponding 
                         accuracy was larger than 99%. A comparison test was performed with 
                         two human observers and our method. The results for the 29 images 
                         collected for several time of days during 50 days in 1999 summer 
                         were compared to visual observations of these same digital images 
                         by two trained field meteorologists. Correlation coefficients 
                         between human observers and the automatic method ranged from 0.84 
                         for clear-sky conditions, and the lowest was 0.09 for 
                         undefined-sky conditions.",
           copyholder = "SID/SCD",
                 issn = "0739-0572",
             language = "en",
           targetfile = "a simple.pereira.pdf",
        urlaccessdate = "16 jun. 2024"
}