SAWS Radar

Radars can provide an indirect estimate of rainfall with high-resolution aerial coverage. Often rain gauges are used to calibrate radar rainfall estimates.

Due to the high cost of procuring and maintaining radars, they are a scarce commodity in most of Africa. However, they are available in South Africa. Until the end of 2009, the South African weather radar network consisted of ten C-band and two S-band radar systems located across the country. This network was used extensively to support weather predictions, storm identification, and aviation applications. Note some of the benefits and limitations of the system:

  • Convective storms were observed very well given their relatively deep vertical dimensions; however, these systems could only be partially seen at long range due to the curvature of the Earth away from the radar beam
  • The spacing of the radars made it difficult to observe stratiform rain; these systems are relatively shallow and radar beams overshoot the echo tops at long ranges
  • The system lacked Doppler capabilities, which can detect the relative movement of rain and ice particles present in active clouds

As of 2010, SAWS is migrating to S-band radar systems in which the signals undergo far less attenuation than C-band signals. These radars have sensitive Doppler capabilities that can detect the internal wind structure of storms, enabling better nowcasting of severe storms. This new radar technology is also very useful for precipitation estimates.

For more information on radar rainfall, see the following COMET modules: