Sferics

Weather News No 3 of October 1956 records that the Bureau had acquired equipment for three atmospheric direction finding (sferics) stations. The equipment was relatively simple, consisting of two crossed loop aerials tuned to 10 kc/s (the radio frequency of the signal produced by a lightning discharge) which with suitable circuitry could provide the bearing of the lightning discharge. Similar equipment had been used on ships and aerodromes to obtaining bearings of radio signals from shore stations or from aircraft. I believe a similar locally built sferics system had been tested during the war by Boswell and Cornish.

The sferics network commenced operation in May 1957 with stations at Eagle Farm, Charleville and Garbutt. A fourth station was established in Cloncurry in April 1959. An additional southern network was established in April 1960, originally with stations at Laverton (Melbourne) and Wilkes (Antarctica), a third station being established at Guildford (Perth) in August 1960. This southern network had the advantage of three widely-spaced stations which assisted accuracy.

The sferics system was an interesting experiment in supplementing the Bureau's overall observations system. It could not be considered as a solution to the problem of routine synoptic analysis as the detection of lightning depended on the occurrence of well-developed thunderstorms, which are daily occurrences in northern Australia and New Guinea at certain times of the year but are relatively rare over the southern coastline of Australia and the Southern Ocean. In certain parts of Australia a thunderstorm is not always accompanied by heavy rain. It is a sign of convective turbulence. Some thunderstorms accompany fronts, others do not.

In summary it may be said that the sferics system was successful in detecting thunderstorms, often in areas of deficient observations. As thunderstorms occur less frequently in higher latitudes there were less occurrences detected in those regions. Sferics were useful for the forecaster, and in alerting electricity authorities of the possibility of power failures. The advent of the meteorological satellite largely replaced the need for sferics observations.

Bureau of Meteorology