Proposal to install oceanographic antennae near
the cliff of Awabakal Nature Reserve
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The purpose of this letter is to provide you with information about a proposed oceanographic study.
Off Redhead, the East Australian Current has great significance for most of us, influencing storms and rainfall, our fisheries and the
coastal ecosystem of sharks.
We propose to install a pair of antennae in the bush near the cliff edge, which will measure the surface currents between Redhead and
Seal Rocks.
The antennae operate in the radio frequency band, on very low power (less than a 60 watt lightbulb); both antennae are connected via
cables just beneath the soil surface to a local resident’s garage on Ocean Street.
What is the study about?
The Sydney Institute of Marine Science was awarded funding from the
NSW government, under the Research Attraction and Acceleration
Program (RAAP), to install a system of ocean monitoring antennae off
the Port Stephens area, to provide ocean currents every hour, out to 200
km offshore. These surface currents will be displayed in real time on
the web for everyone to access.
Area
covered
The ocean east of Redhead is a key area for eastern Australia and its
population, where the warm East Australian Current moves offshore
and forms a complex region of ocean eddies, which are so important for
the local ecosystem.
What will we install?
We can measure the ocean currents offshore by positioning a pair of antennae at Redhead and another
pair at Seal Rocks. The antennae are manufactured by CODAR (http://www.codar.com/index.htm).
One of the antennae transmits 4 MHz waves that reflect off the ocean surface and back to the receiving
antenna, and the change in the reflected signal (the doppler shift) gives us information about ocean
currents and waves. Note these antennae are completely harmless to humans and animals.
Once the antennae are installed, they can be left in place for
years, with very few maintenance visits needed (one every 6
months or so). Antennae have been deployed to measure
currents off many coasts around the world, especially
California: http://www.sccoos.org/data/hfrnet/. One system is
deployed off South Australia, and another off Western
Australia; a similar type is installed off Coffs Harbour:
http://oceancurrent.imos.org.au/SAgulfs/latest.html
Building 19 Chowder Bay Road, Mosman NSW 2088
612 9435 4600 | sims.org.au | [email protected]
Benefits to the NSW community
The complexity of our coastal ocean creates a wealth of opportunities and also problems. Recent issues
include shark attacks, wave climate, marine parks, fisheries, offshore aquaculture, beach erosion,
coastal flooding, algal blooms and artificial reefs.
Coastal ocean circulation is difficult to understand and forecast, especially off NSW because of the
variability of the East Australian Current coupled with coastal winds, tides, and waves. With improved
knowledge of coastal currents we can we can, for example, determine the ocean habitat of sharks and
baitfish.
Location and appearance of antennae
Approximate location of the antennae is
indicated by yellow blobs. The northern
transmitting antenna is white, 11 m tall, rather
like a flag-pole with a small white fence
around it. Depending on testing, another
antenna may need to be installed 30 m inland.
The southern receiving antenna is 5 m tall, also
with a white fence. Neither antenna will be
visible from the road. The cables (dash lines)
will be buried in conduit and connected to a
communications box in a local garage. There
will be signs to explain the system and a web
link to the ocean current maps.
The transmitting antenna will have temporary guy ropes for testing, before it is bolted into place. The
site will require minimal trimming of native vegetation (or we will remove weeds); we will need to
hedge-clip any vegetation more than 1 m high around each antenna. The receiving antenna is shown on
the first page.
If you have any questions or concerns, feel free to contact:
Professor Iain Suthers: 02 9385 2065 • [email protected]
Dr Matt Archer: 02 9385 7090 • [email protected]
We will endeavour to keep you informed as we move through the
approvals process and should it be necessary, hold a community
consultation visit in the near future.
Yours sincerely,
Professor Peter Steinberg
Director and Chief Executive Officer
Sydney Institute of Marine Science
19 Chowder Bay Road, Mosman NSW 2088
Building 19 Chowder Bay Road, Mosman NSW 2088
612 9435 4600 | sims.org.au | [email protected]