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Estimation of daily rainfall over the upper Nile river basin using a continuously calibrated satellite infrared technique

Published online by Cambridge University Press:  01 September 1999

M C Todd
Affiliation:
School of Geography, University of Oxford, Mansfield Road, Oxford, UK
E C Barrett
Affiliation:
Department of Geography, University of Bristol, University Road, Bristol, UK
M J Beaumont
Affiliation:
Department of Geography, University of Bristol, University Road, Bristol, UK
T J Bellerby
Affiliation:
Department of Geography, University of Hull, Hull, UK
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Abstract

A continuously calibrated infrared (IR) geostationary satellite rainfall estimation technique (CCB4) is introduced, in the context of the Nile River Forecast System, an operational system for hydrological modelling and forecasting. The CCB4 incorporates near-real-time rain gauge data to continuously calibrate optimum IR rain/no-rain thresholds and daily rain rates on a daily time step. The ability of the CCB4 and two comparative techniques to estimate daily rainfall at the regional and pixel scales is assessed, using Meteosat IR imagery and gauge data from six wet season months covering three years. The CCB4 shows improved skill in identifying rain days and estimating daily rain amounts at a range of spatial scales, from regional to pixel scales. At the pixel scale, however, improved root mean square errors remain relatively high, ranging between 66% and 84% of the mean unconditional rain rate.

Type
Research Article
Copyright
© 1999 Meteorological Society

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