Marine Observations in the Bureau of Meteorology
Observations of weather, ocean surface and sub-surface conditions are vital for weather and seasonal climate forecasting and for detecting global climate change. The Bureau operates a number of marine observing networks to provide data for day to day weather forecasting for the public and the marine user communities in Australia. The data are also used internationally as input to computer-based weather and ocean prediction systems, and for supporting seasonal scale climate prediction for events such as El Niño/La Niña in the Pacific.
The data are transmitted around the globe for use by other national weather and ocean services for their own forecasting purposes. The observations are also archived as a long-term record of how the world's climate may be changing.
A specialist Marine Observations Unit was established by the Bureau in 1997 to manage its marine observing networks, including the Australian Voluntary Observing Fleet and Port Meteorological Agents; Ship-of-Opportunity Program; drifting, moored and waverider buoy programs; automated shipboard weather observing systems; and any other operational marine networks developed in the future.
Australian Voluntary Observing Fleet
The Australian Voluntary Observing Fleet (AVOF) is a network of approximately 90 ships operating mainly in the Australian region, that are recruited to take, record and transmit routine weather observations whilst at sea, including sea state and swell conditions.
The AVOF consists of Australian and foreign owned merchant, research, passenger and private vessels. The Bureau supplies the necessary meteorological equipment and stationery to the recruited vessels and provides the crew with any additional training that may be necessary.
Most observations from ships of the AVOF are transmitted using the Inmarsat satellite communication system.
The AVOF forms part of the World Meteorological Organization's fleet of approximately 7000 Voluntary Observing Ships worldwide.
Drifting Buoy Program
The Bureau has been involved with drifting buoys since the First GARP Global Experiment (FGGE) in the 1970s. Between the mid 1980s and 1994, the Bureau maintained a modest buoy program of about six buoys per year, supplemented by an equivalent number of buoys provided by the National Data Buoy Center in the USA, in support of TOGA (Tropical Ocean Global Atmosphere). Since 1995 the Bureau's buoy program has increased to about ten Bureau funded buoys per year.
The Bureau uses two types of buoys which are deployed from member ships of the AVOF and the Navy in the Indian and Southern Oceans, as well as the Gulf of Carpentaria.
Data from drifting buoys are transmitted using the Argos satellite based location and collection system.
The picture at right shows the deployment by crane of a drogued FGGE type buoy.
Visit the Data Buoy Cooperation Panel for more information about the international program to deploy drifting buoys.
Ship Of Opportunity Program
The Ship-of-Opportunity Program (SOOP) is a network of ships that launch expendable bathythermograph (XBT) probes to determine the thermal structure of the upper 800m of the oceans.
The upper ocean data collected by the XBT is a major reason for our increased knowledge of the interaction between the atmosphere and the oceans. The data also provide an indication of major climate events such as El Niño/La Niña. Apart from climate prediction, the data also supports other operational requirements (fisheries, shipping and defence) by providing upper ocean data for assimilation in models and ocean analysis schemes
Originally a research project developed and operated by CSIRO Marine Research (CMR) in Hobart, the low density network transferred to the Bureau as an operational network on January 1, 1998. CMR continues to operate a high density XBT research network.
The Bureau's low density network currently consists of seven ships sampling on seven predetermined lines. Each line is traversed on average at least once per month with an XBT probe launched every four to six hours.
The descending XBT probe samples the water column every 60cm during its fall, relaying thermal data to a shipboard processing unit via thin copper wire which unspools from within the XBT and from a coil on the launch vessel. The XBT schematic at right shows the spool of copper wire inside the probe.
Low resolution XBT data to satisfy operational requirements are transmitted from Bureau XBT vessels using the Argos satellite based location and collection system. High resolution, or complete profile data for research applications, are stored to disk and recovered when the vessel berths at a major Australian port.
Waverider Buoy Program
The Bureau has recently implemented a strategy to develop a National Waverider Buoy Program based around existing waverider networks operated privately or by state or local authorities. These networks will supplement the Bureau's own waverider buoy located off the west coast of Tasmania near Strahan.
A Waverider buoy, pictured right, follows the movements of the sea surface, and determines the wave height by measuring the vertical acceleration of the buoy. Sea and swell conditions are a major component of coastal and ocean forecasts, but they have largely been estimated in the past, and generally only available during daylight hours.
The Strahan waverider buoy was deployed in January 1998 and has recorded maximum waves of 18m within the first three months of operation. The Strahan buoy is supported by CMR which provides the moorings, and the Strahan fishing community which provides the resources to deploy and recover the buoy.
The Bureau currently also receives wave data from networks operated by:
The Bureau is also investigating a cooperative waverider buoy project in the Port Lincoln - Kangaroo Island area of South Australia with a number of possible stakeholders.
For more information contact the Marine Observations Unit.