Keynote: Weather Radar Networking in Southern Africa

Weather radar is one of the cornerstones of meteorological service delivery to support socio-economic development. This is especially true in the developing countries of southern South Africa where intense thunderstorms and other severe weather events are common. The South African Weather Service (SAWS) has gained international recognition for its achievements in the field of weather radar operations and applications. At present the 11 radars in the National Weather Radar Network (NWRN) are between 11 and 31 years old and represent technology of the 1970s and 1980s. However, an in-house team of engineers have ensured that the systems operate reliably. This team will deploy two further old S-band radars after being suitably upgraded, east of the eastern escarpment of South Africa over the next year to improve coverage of these low lying areas where severe storms frequently occur.

In-house upgrades, especially with regards to signal processing, antenna control and networking software has ensured that the data collected by these radar systems remain usable despite the fact that the basic radar systems are old and do not represent state-of-the-art technology. SAWS has opted to base all its weather radar data manipulation on the NCAR developed Thunderstorm Identification Tracking Analysis and Nowcasting (TITAN) system and its underlying data formats and structures. Since 1998 the TITAN system has systematically being upgraded to include routines that facilitate the compositing data from several radars in a network. TITAN display systems have also been provided to all the forecasting offices in South Africa. Both the National Meteorological Services in Botswana and Mozambique have in recent years deployed new generation radar systems and plan to expand the weather radar coverage in their countries. Botswana currently operates a USA-built S-band Doppler radar close to its capital Gaborone and Mozambique operates two German manufacture C-band Doppler radar systems, the one at Xai-Xai and the other at Beira.

In the past year the good cooperation between the National Meteorological Services of Botswana, Mozambique and South Africa has resulted in the exchange of weather radar data. Systems were introduced in Botswana and Mozambique that converts and ingests data from the processors of these systems into TITAN. In South Africa these data streams are merged to generate a regional radar mosaic. The radar data obtained in this manner can also be overlaid by Meteosat 8 data and that provided by the newly installed SAWS lightning detection system.

As an integral part of the recapitalisation plan of SAWS, ten new state-of-the-art, S-band Doppler radar will be commissioned over the next 4 years. The SAWS plans to deploy the first two of these new sophisticated weather radars at Bethlehem and Irene This will ensure that radar research in the Bethlehem area and the Gauteng province with its high population density are the first beneficiaries of the new technology. Some of the current C-band radars will be reallocated.

Modern weather radar systems have enhanced performance and the analogue components in both the receiver and transmitter have been replaced by digital components that result in more stable calibrations. The antennas have also been drastically improved. These advances translate into improved meteorological and hydrological service delivery and enhanced reliability and ease of maintenance. Recent weather radar related developments in southern Africa auger well for the future of weather radar and its applications.