Ocean network

Learn about the weather buoys, floats and ships we use to collect marine data

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About marine observing systems

We collect marine observations from equipment:

  • in the ocean
  • on ships that are part of World Meteorological Organization volunteer programs.

In the ocean, our equipment includes:

  • drifting buoys
  • wave buoys
  • argo floats.

The tsunami detection system, offshore automatic weather stations and tide gauges are also part of our ocean network.

Data from the ocean network is used:

  • nationally – in weather forecasting on land and at sea
  • internationally – contributing to large-scale weather and ocean prediction schemes
  • globally – in climate monitoring, research and prediction. This includes for events such as El Niño and La Niña in the Pacific.

Drifting buoys

Meteorological drifting buoys move with surface currents. They measure atmospheric pressure and sea surface temperature from all ocean areas.

A drifting buoy is made up of a:

  • surface buoy with a barometer on top
  • sea surface temperature sensor mounted just below the surface
  • holey-sock drogue that ensures the buoy drifts with the surface currents
  • tether connecting the surface buoy to the drogue.

We have a fleet of 30 active buoys that travel great distances over many years.

By tracking the buoys' path we also measure water movement. This uses a technique called Lagrangian current, which measures the path of a water particle over a long time.

The buoys are often released by volunteer ships along common trading routes.

Video: The journey of a drifting buoy

Explains what a drifting buoy is and explores Australia's network of this observing equipment.
Drifting buoys move with surface currents. They measure sea surface temperature and atmospheric pressure.

Components of a drifting buoy:
• a holey-sock drogue ensures the buoy follows the movements of the water at about 15 m depth,
• a sea surface temperature sensor near the surface,
• a tether connecting the sensor to the drogue,
• a surface buoy and barometer on top.

BOM maintains a fleet of 30 active buoys that travel great distances over many years.

A drifting buoy was deployed on 5 December 2014 south of Fremantle in Western Australia. By 2018 it had travelled across to the west coast of South America.

Drifting buoys are located to the north, east and south of Australia.

Wave buoys

Wave buoys measure wave characteristics, including:

  • height
  • direction
  • period – the time between waves.

A wave buoy has 4 parts:

  • a surface buoy designed to follow the movement of the ocean
  • accelerometers inside the surface buoy measure the up and down motions
  • an anchor to keep the buoy in one place
  • a rubber cord that can stretch 3 times its length connects the buoy to the anchor.

Measuring the up and down motions of the water surface enable us to calculate wave height, direction and period. For more about wave height, view our Waves and swell page.

We operate 4 wave buoys and receive data from other networks operated by state government agencies in:

  • New South Wales
  • Queensland
  • Victoria
  • Western Australia.

Video: How do wave buoys measure around our coastline?

Explains what a wave buoy is and how it is used.
Wave buoys measure waves around the Australian coastline.

Components of a wave buoy:
• Buoy designed to follow the movement of the ocean
• Accelerometers on the buoy measure the up and down motions to calculate wave height, direction and period
• Rubber cord capable of stretching 3 times its length dangles below the buoy.

BOM uses this data to issue marine warnings.

Argo floats

Argo profiling floats drift at depths of 1–2 km and return to the surface every 10 days.

They measure temperature and salinity at different levels as they rise and send this information to a satellite when they surface.

The float then starts the cycle again.

Our profiling floats contribute to Argo Australia, part of a global array of these profiling floats.

Video: The cycle of an Argo float

Explains what an Argo float is and how it collects data from the ocean.
Argo is an international fleet of underwater robotic instruments. The program collects real-time data that informs BOM's weather forecasts and climate predictions.

Cycle of an Argo float:
• Descends to drifting depth at 1000 m.
• Drifts for 8–10 days.
• Descends to profiling depth at 2000 m.
• Begins measuring temperature and salinity.
• Continues measuring on the ascent.
• Surfaces to transmit data via satellite.
• Starts next cycle.

Volunteer ships

Australian Voluntary Observing Fleet

Australia takes part in the World Meteorological Organization's (WMO) Voluntary Observing Ship scheme. There is a national fleet of ships that record and report weather observations at sea.

About 50 Australian and foreign-owned merchant, research, passenger cruise and private vessels make up the Australian Voluntary Observing Fleet. These ships:

  • record observations close to Australia
  • often launch drifting buoys.

Helping ships provide accurate observations

We supply the ships with the meteorological equipment and train the crew to use it. Most of the weather observations are for:

  • temperature
  • barometric pressure, or mean sea level pressure (MSLP)
  • waves
  • wind speed and direction
  • sea surface temperature
  • visibility.

Our Port Meteorological Officers, based in Fremantle and Melbourne, maintain contact with the ship masters and crew. We routinely visit the ships to help calibrate and service equipment such as barometers used to measure MSLP.

Ships can also independently calibrate their barometers using MSLP observations from automatic weather stations around Australia.

Probes dropped from ships

We also take part in the WMO's Ship of Opportunity Programme. Our fleet is made up of 5 volunteer ships that drop probes every 4 hours on selected global shipping routes.

The probes measure the temperature of the ocean from the surface to 800 m depth. The sampling is performed using a probe known as an expendable bathythermograph (XBT). Some of these routes have been continuously sampled for more than 20 years.

Join the volunteer observing fleet

To enquire about registering your vessel with the volunteer observing fleet, use the enquiry form on our Contact page.

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