Macquarie Island is one of the few landmasses in the Southern Ocean and is situated just to the north of the Antarctic convergence zone. The meteorological data collected from this station is invaluable for input into global numerical weather products and the ongoing long–term climate record for the region. Macquarie Island data contributes to the Global Climate Observing System (GCOS) and the Global Upper–Air Network (GUAN) and is considered as the most influential station in the Bureau upper air network.
Meteorological observations have been continuously recorded on Macquarie Island since the establishment of the ANARE station in 1948. The Bureau of Meteorology observation program primarily consists of surface, upper air and ozone measurements with technical and operational support given to other atmospheric research programs that utilise the islands unique location. This year our team consists of three members: Matt and Kerri (observers) and Emry (technician).
Our observation program runs every day of the year with the Automatic Weather Station (AWS) recording one–minute data for temperature, humidity, barometric pressure and wind speed and direction. This information is supplemented with manual observations of the weather, visibility, cloud cover, sunshine hours, soil temperature as well as sea and swell observations.
The upper air program involves releasing hydrogen filled balloons into the atmosphere every 12 hours. The balloons carry aloft a device called a radiosonde which has a suite of sensors and GPS technology that produce a profile of the temperature, humidity, barometric pressure as well as determining the wind speed and direction of the upper atmosphere up to 35 kilometres above the Earth’s surface. An ozonesonde is incorporated with the radiosonde flight once per week. The ozonesonde samples the amount of ozone in the atmosphere as the balloon ascends producing a profile of atmospheric ozone levels in this region.
Another daily task that staff perform is the manual taking of ozone measurements utilising an instrument called the Dobson Spectrophotometer.
The first Dobson was built in the 1920s for the purpose of measuring total ozone in the atmosphere with little change to the instrument since its inception. The basic principle in Dobson Spectrophotometry is the comparison of the intensities of two ultraviolet wavelengths. One of these wavelengths has been highly absorbed by the ozone layer while the second is essentially unaffected. The difference in the two intensities relates to how much ozone is present in a vertical column extending from ground level to the top of the atmosphere in the vicinity of the instrument. The small concentration of ozone that is present in the atmosphere is important due to its ability to absorb UV radiation from the sun and also its influence on the thermal structure of the atmosphere.
The meteorology technician is responsible for the maintenance of all the meteorological instrumentation and equipment, including the hydrogen generation systems and facilities. In addition, he/she is responsible for the support and maintenance of other non–Bureau science experiments such as the ongoing CO2 monitoring by the CSIRO. This year, there is also the Macquarie Island Cloud and Radiation Experiment (MICRE) which consists of an array of instrumentation.
Our team’s aim this year is to maintain the high quality of data collection that has been recorded by previous Met teams as we approach 70 years of operations on Macquarie Island, and to begin the process of preparing for hopefully another 70 years of operations.