Rainfall forecasting using remote sensing data in Bangladesh

M. M. Hossain 1, A. S. Islam 2, M. R. Islam 1 and S. Saha 1

Department of Water Resources Engineering, Bangladesh University of Engineering and Technology (1)
Institute of Water and Flood Management, BUET, Dhaka-1000, Bangladesh (2)

An attempt has been made to estimate rainfall in Bangladesh from GMS-5 data using Convective Stratiform Technique (CST). Estimated rainfall was calibrated with rainfall data of rain gauges obtained from Bangladesh Meteorological Department (BMD). The rainfall stations are located at different parts of the country. For this purpose rainfall and cloud characteristics were studied. A number of computer programs were developed for image processing of GMS data and for CST analysis. All these programs were written in 'C' language, compatible in all MS-DOS/Windows based operating system and can run independently with little execution time and effort. To adapt CST algorithm in Bangladesh region, some modifications were made in calculating slope parameter, determining stratiform threshold temperature and assignment of both convective and stratiform rain rates. CST rainfall was calculated for the whole country and calibrated against BMD rainfall data. It was found that CST rainfall had better agreement with raingauge data than the calculated GMS-5 Gross Precipitation Index (GPI) rainfall. By CST method the deviation from raingauge value was 1.2 mm to 15.2 mm per day while by GPI method it varied from 1.0 mm to 22.5 mm per day. This result appears to be encouraging but not conclusive because of non-availability of long-term data. It is recommended that long term data should be used for verification of convective and stratiform rain rates.

Keywords: convective stratiform technique, GMS satellite, rainfall forecasting

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