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Willis Island Meteorological station is one of 65 manned Weather Observation stations in the Australian Observing Region. The stations are scattered over the entire mainland, and surrounding islands as well as 3 stations in Antarctica. Each station provides around the clock weather information reflecting current weather conditions at each site, this information recieved is part of the world wide collection of data which is used as input into the weather bureaus 'super computer' which models the global circulation of the earth's weather patterns.
Willis Island in particular is of extra importance for the Queensland weather bureau as it provides observations for the Coral Sea which helps forecasters monitor and predict the formation, development and movement of Tropical Cyclones that may cause a threat to the East Coast of Australia.
The first basic principals of observing the weather is to make a visual observation of the weather from ground level every three hours. This Observation is called a synoptic report: which includes a visual observation of the sky, including description of weather in the area, cloud types and heights and sea observations, this information is coupled with temperatures & humidity, Rainfall, wind direction and speed and station level air pressure. This Data is collected from two different forms of instrumentation: The AWS - Automatic Weather Station, where all the necessary data is measured every minute through Automation, This data collected from the AWS is the primary source for the reporting of data, however this is checked to manually read instrumentation to ensure accuracy. Below is some of the equipment that measures climatic elements.
The Stevenson Screen -
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The Stevenson screen is built to house and reflect direct radiation from the sun while maintaining a well vented environment so as to best measure the current state of the local atmosphere. The instrumentation inside includes four glass thermometers and 2 sensor probes. These thermometers combine to measure the current Dry Bulb Temperature of the air, the Wet bulb temperature, as well as the minimum and maximum temperatures for the most recent 24 hours. The 2 sensors are part of the AWS, measuring temperatures at 1 minute intervals. |
The Wind Anemometer -
| The Wind Anemometer stands at a height of 10 metres above ground level in a clear and open environment so as to not be affected by any local influences such as wind tunneling around buildings etc. The cups at the top of the mast spin, measuring the winds velocity, while the wind vane will rotate pointing into the direction of the wind, as it rotates the potentiometer built inside allows the AWS to record the direction to which the wind vane is pointing. |
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Rainfall -
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The 'Dines Pluviograph' and The 'Tipping Bucket Rainguage' are both used
to measure rainfall amounts and intensity. The Pluviograph on the left consists of a tilting siphon that catches the rainfall, It then transcribes data onto a time scaled chart as seen inside the casing. The Tipping bucket Rainguage, viewed right, catches the rain in the top orifice which then falls into one of two little buckets that hold 0.2mm of water, as each one fills it tips like a see saw allowing the other bucket to fill while striking an electrical pulse which is measured by a counter. Both devices are checked by the more common rain gauge which is a specific sized measuring cylinder. |
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The information recorded by these instruments is displayed at the AWS console. Data from here is then coded into a number string for easy transmission along with the observers visual observations to the Regional Forecasting Centre.
The photo on the left below shows the AWS console, with both digital and paper printed recording of data. The PC on the right is used for the transmission of data, while the field book seen in front of the PC is used to keep a station record of all observations sent, which is then archived as part of the climate record for the station.
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'Upper Air' Observations are also performed at the station on 6 hourly intervals coinciding in time with every other meteorological station world wide. The Upper atmosphere observations are performed by collecting data with the use of weather balloons. There are 4 balloons released per day, three of which give us wind only data while the other flight gives us wind and Temperature Data.
Below you can see a) the balloon being filled with hydrogen gas. The Hydrogen gas is very flammable and if the balloon bursts and causes a spark then an explosion will take place, hence the protective gear - flash Jacket, Goggles and Gloves and anti static footwear, which helps to keep you earthed to the ground which in turn minimises any static electricity produced which could produce a spark and hence an explosion.
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Due to the dangers of using Hydrogen Gas, steps have been taken to decrease human interaction with the balloon filling procedure. The Remote Balloon Launcher was built so that the observer does not have to come in contact with the balloon at any time that Hydrogen is present.
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The balloon is prepared and then placed on the filling table as seen inside the RBL. Hydrogen is pumped out through gas lines and with the aid of a moving piston which is controlled by Hydraulics the balloon can be released from the press of a button from a remote location. The walls on the RBL are designed to minimise and absorb the effects of an exploding Hydrogen Balloon |
The Hydrogen that is used to fill the balloons has two different sources. The first source is that of a commercial gas supply delivered in high pressure gas bottles. The other Hydrogen source is that of hydrogen made on site, which is the case on Willis Island given its remote location.
The Process of making or extracting Hydrogen gas comes by the use of a 'catalytic Converter' known as a 'Electrolyser'
When electricity is passed through water, the water is broken down into Hydrogen and Oxygen gases from which it was formed. The Hydrogen generating plant (Electrolyser) makes use of this process. The Hydrogen produced is collected and stored in the tanks seen below, while the oxygen is wasted to the atmosphere. Potassium Hydroxide is added to the water to reduce the resistance to the electric current passing through the water, hence the solution becomes an 'electrolyte'.
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Once the balloon is filled with Hydrogen and released it is then tracked by a Radar so that its movements can be tracked a by use of simple time vs distance formulas, the balloons movements can be transformed into wind speed and direction for heights from ground level up to 10 000 metres high, ie. to the edge of our atmosphere.
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The Bureau of Meteorology operates several Radar types to perform both
upper wind observations and Radar Weather Watch. The Willis Island Radar on the left
is a WF100 model. These Radar's can function as either manual or automatic track
radar's. Features of the WF100 Radar is the user interface (computer terminal) known as PC RADWIN, a wind data processor (which computes wind speed and direction), a printer and an optical tracker unit which allows the operator to remotely acquire a target at close ranges. |
Once Daily one of the balloons is attached with what is know as a 'Radiosonde' and released. As the Radiosonde and balloon ascend through the atmosphere, successive Pressure, Temperature, and Humidity measurements are transmitted to the ground equipment which gathers and processes them into vertical profiles. Graphical screen displays report the progress of the sounding in real time. The observer performs editing functions on the data received during the balloons ascent and communication messages are relayed to forecasters on the mainland and to the National Climate Centre (NCC).
The photos below show the Radar's user interface and the radio frequency receivers of the sonde. Pictured below right is the actual radiosonde that is attached to the balloon which transmits the data to ground equipment.
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So that is Observing in a nutshell, job requirements change from station to station depending on its location. At present the most important thing for our station is to maintain a good observing routine so as to aid forecasters in the prediction and monitoring of Tropical Cyclones, however when I work back on the mainland next month the main task of observing for me will be to provide timely and up to date Aviation weather as the station I work at in Wagga is located at an airport.
If you would like to know anymore information on anything presented on this page then feel free to email me.
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