Cloud cover estimation using multitemporal hemisphere imageries

M. Yamashita, M. Yoshimura, T. Nakashizuka

    Research output: Contribution to journalConference articlepeer-review

    32 Citations (Scopus)


    The solar radiation is the origin of energy for the photosynthesis and forest productivities. On the other hand, clouds constantly appear, move and disappear all the time and influence atmospheric and radiation conditions at the same time. Therefore, to understand cloud parameters which consist of cloud covers, its distributions and types etc. for a short time interval can help us to estimate solar radiation or photosynthetically active radiation (PAR) with high accuracy. Authors have been observed and measured various parameters related with photosynthesis and carbon exchange for tropical rain forest in Borneo Malaysia so far. Concerning to the cloud conditions, we also monitor the whole sky using the commercial digital camera with the fisheye converter lens and can obtain hemisphere imageries about every two minutes interval. As the experimental study about cloud parameters, in this paper, we present 1) the observation system of whole sky conditions, 2) how to analyze the obtained hemisphere imageries and 3) the method to estimate cloud cover and understand cloud distribution with sun position. Here, we use Sky Index which is calculated using visible RGB image taken by digital camera. This index is useful to separate whole sky area to clouds and the blue sky areas. Then multi-temporal cloud covers can be estimated from the Sky Index generated by multi-temporal hemisphere imageries. Through this study, we also could recognize the efficiency to understand cloud cover, cloud distributions and types by using hemisphere imageries and Sky Index. As the continuous works, we examine the relationship between the solar radiation and cloud conditions such as cloud covers, distribution and types.

    Original languageEnglish
    Pages (from-to)826-829
    Number of pages4
    JournalInternational Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives
    Publication statusPublished - 2004 Jan 1
    Event20th ISPRS Congress on Technical Commission VII - Istanbul, Turkey
    Duration: 2004 Jul 122004 Jul 23


    • Atmosphere
    • Estimation
    • Monitoring
    • Multitemporal
    • Parameters
    • Radiation

    ASJC Scopus subject areas

    • Information Systems
    • Geography, Planning and Development


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