The characteristics of rainfall and melting layer in Singapore: experimental results from radar and ground instruments

The radio frequencies used by current and future satellite communications systems have been gradually shifted towards higher bands due to a rapidly increasing demand for bandwidth. At higher frequencies, such as Ku-band systems, which have been deployed widely in most of the Asian countries, rain-induced attenuation can severely affect the availability of the Earth-satellite communications service. In particular, tropical regions have posed extra difficulties in predicting attenuation due to the lack of understanding of tropical precipitation and climate, e.g., rainfall intensity and rainfall heights. Moreover, millimetre wave specific attenuation is very dependent on raindrop size distributions. In addition, total path integrated attenuation on satellite paths depends on the maximum height of rainfall. To explore these uncertainties, the Radio Communications Research Unit (RCRU) at Rutherford Appleton Laboratory (RAL) installed a tropical rain radar in 1998. We aim to study the characteristics of tropical rainfall and predict attenuation by utilising data gathered by rain radar, distrometer and a ground-based beacon receiver. Moreover, this radar has been involved with the ongoing Tropical Rainfall Measurement Mission (TRMM) and EuroTRMM projects to improve our understanding of the characteristics of tropical rainfall.