Derivation of path reduction factor from the malaysian meteorological radar data

Abstract

Rain does not distribute evenly in a region experiencing precipitation. This is especially true in tropical regions as rain has been found to be more convective in nature rather than widespread. ITU-R has given the necessary information to calculate the attenuation due to rain in dB/km. However, to predict the total amount of attenuation due to rain that a microwave link might suffer, a path reduction factor is needed to account for the variability of rain rate occurring along the propagation path. This paper presents a study of rain rate distribution in Malaysia using the Malaysian Meteorological radar data. The radar station is located in Kluang, Johor. Readings from the scanning angle of 0.5o and from bins 32 to 51 were utilized in this study. Data were collected from 2nd January 1998 to 10th March 1998. Total scans where rain is detected were 7998 scans. Analysis from this study confirmed that rain cell in Malaysia is highly convective and heavy rain occurs in patches or in an area of about 1.2 km in diameter. This preliminary analysis proposed a path reduction factor r derived from the radar data that can be used for predicting attenuation due to rain. Better radar specifications can produce a more accurate reduction factor. This will enable a reliable microwave link system planning and design to be obtained.