History and operations of Mt Gambier Meteorological Office

Meteorological observations commenced in Mt Gambier in 1861, when daily rainfall readings commenced at the Post Office. The Bureau of Meteorology opened an office at the Mt Gambier airport in 1941, with three staff members, on what was then an RAAF training base.

Observations continued from the control tower on the airport up until 1963, when the office was moved to its present location on a small rise overlooking and adjacent to the airport.

The office is about ten kilometers north of the City of Mt Gambier.

In 1967 the second WF44 radar purchased by the Bureau of Meteorology was installed at Mt Gambier. This radar is now the longest serving WF44 radar in the inventory but it will be replaced late in 2003 with a new WF100 radar.

The operational hours are from 5.30am to 10pm, seven days a week. We provide meteorological information to a wide range of public interests in an area extending from Warrnambool in the east to Keith and Bordertown in the north.

The Mt Gambier MO is one of 4 Bureau staffed stations in South Australia providing a vital role in Australia's surface and upper-air measurement network. Weather balloons are released 3 times per day. Information about temperature, humidity, pressure and wind profiles from the surface to a height of about 27kms (90,000ft) is gathered from these balloon flights. Surface observations of wind, pressure, temperatures, visibility, precipitation, weather phenomena, evaporation, etc, are recorded at regular intervals throughout the day and night. Limited observations are recorded and transmitted by an automatic weather station when staff are not present.

Radar

The weather finding radar is used to automatically track a target suspended under a balloon and compute the wind speed, wind direction and the height of the balloon as it ascends through the atmosphere. Typical balloon flights last about 90 minutes, reach heights up to 27 km and the balloon can often travel 200 km downwind before it bursts. Balloons are normally released three times each day.
Apart from tracking weather balloons, the radar is used to detect precipitation (rain, snow and hail). It estimates precipitation intensity from the strength of the returned echoes. It can detect light rain to a distance of about 200km and severe thunderstorms to over 300km, limited mainly by the earth's curvature. The radar displays a map of colour graded precipitation distribution and intensity on a PC monitor in the MO. This image is updated every 10 minutes when the radar is not being used for balloon tracking. These images are available in the observations section from the field office main page.

Radiosonde

Radiosondes are small battery powered radio transmitters that are carried through the atmosphere under a weather balloon. The radiosonde contains a small aneroid barometer and temperature & humidity sensing elements. When operating, the radiosonde transmits radio signals indicating pressure, temperature and humidity to a receiver in the MO. Radiosondes are released world wide at scheduled times. In South Australia, radiosondes are released daily at 8.45am. At Mt Gambier, additional radiosonde flights are also released on Tuesday and Thursday evenings at 8.45pm. The signals that the radiosonde transmits back to the MO are processed by a computer and displayed graphically on the computer screen. The data received from the radiosonde enables a temperature and moisture profile of the atmosphere to be calculated. As the data is displayed it is manually scrutinised and modified if necessary before being encoded and transmitted to the Bureau's communications network for national and international distribution.

Weather Balloons

Meteorological balloons are inflated with hydrogen. They are filled with sufficient gas to cause them to ascend through the atmosphere at about 300m (1,000ft) per minute. As air pressure decreases with height, the balloon expands in size until it finally bursts. During the hours of darkness balloons are released with a small torch attached under the target to allow visual tracking for the first few minutes before the radar acquires and automatically tracks the reflective target suspended under the balloon. The hydrogen used to inflate the balloon is a highly flammable gas and safety precautions must be strictly followed when inflating and handling weather balloons. These precautions include the wearing of an anti-flash coat, goggles, gloves and antistatic boots. As the balloon is inflated, overhead sprinklers ensure the balloon and surrounds are wet in order to reduce the chance of static electricity build-up.

Radio Broadcasts

Mt Gambier Weather Office staff are heard on local radio on the ABC (5MG) six mornings a week following the 7.30am news and on commercial radio (5SE) five days a week at about 12.20pm as part of the midday news broadcast.

Your feedback on the services provided by the Mount Gambier Field Office and the Bureau of Meteorology is most welcome. Contact details are provided from the field office main page.