Estimation of Surface Temperature and Rainfall in Ghana |
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| Authors: | V CK Kakane H Søgaard |
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| Institution: | 1. Physics Department , University of Ghana , Legon , Ghana;2. University of Copenhagen, Institute of Geography , ?ster Volgade 10, Copenhagen , Denmark |
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| Abstract: | Geografisk Tidsskrift, Danish Journal of Geography 97: 76–85, 1997. Daily Meteosat images for 1989 have been analysed for the purpose of mapping surface temperature and rainfall in Ghana. The images in the time-series are georeferenced and the maximum value composite (MVC) technique is applied to the temperature calibrated IR-channel images after a cloud screening of the images. The cloud covered areas are outlined and traced using the Meteosat visible channels. Stratiform clouds are detected using surface albedo while cumuliform clouds are detected based on a technique calculating the spatial variability within a 5 pixel by 5 pixel window around each point in the image. The cloud covered parts of the scene are then delimitated by comparing the normal albedo values and the spatial variance in albedo. The paper then discusses how the outlined procedure can be applied in an environmental monitoring context. For each of the months June to November 1989 the mean monthly rainfall amounts at 35 meteorological stations are plotted against the mean surface temperature. It is found that apart from the month of June statistical significant linear relationships are obtained and that the scattering around the line is decreasing for increasing sampling length. |
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| Keywords: | Meteosat AIVH data NOAA AVHRR visible image albedo infra red image surface temperature delimiting cloud albedo variance rainfall correlation |
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