SAIMOS: The Southern Integrated
Marine Observing System (2007-2011): $5M NCRIS Funding
SAIMOS is a joint initiative of Flinders University
and SARDI Aquatic Sciences and is supported by Marine Innovation South
Australia (MISA).
Node Leader: Laurent Seuront
Mooring and HF RADAR Facility Leader: John Middleton
In 2007, $55M was awarded by the Commonwealth
Government to proponents of the national
Integrated Marine Observing System (IMOS). This observing system
consists on satellites, sub-surface moorings, ocean gliders, HF Ocean
RADAR, Argo floats and ship-based field work. IMOS is designed to
measure, monitor and understand deep ocean currents, coastal boundary
currents and marine ecosystems that under-pin fisheries. As the
beginning of long-term monitoring the impacts of climate change will be
better understood.
One of 4 coastal nodes, SAIMOS will provide
extensive data streams of ocean currents, temperature, salinity and
biological indicators such as nutrients and fluorescence. The purpose of
SAIMOS is to provide data that will permit us to understand long-term
changes in boundary currents as well as the circulation and planktonic
ecosystems that are fed by the upwelling of nutrients from the deep
ocean: a numerical simulation of such upwelling is shown in Figure 1
where south-easterly winds drive cold (nutrient rich) water onto the
shelf (the dark blue).
Figure 1.
The results of upwelling on bottom temperature in a numerical model (SAROM
I) of Middleton and Platov (2005) and for 6 February 1999: winds and
currents had been upwelling favourable for 10 days prior to this date
and water has been upwelled from depths of 250 m to the south and
south-west of Kangaroo Is. The coldest plume follows the 0.1 km (100 m)
isobath indicated by the black line. Only water of temperatures 12.5 to
18 oC has been colour contours. The vector legend indicates
current with amplitude 5 cm/s.
The SAIMOS data are to be obtained from fixed
moorings (Fig 2), HF Ocean RADAR, satellite tracked gliders and SARDI’s
RV Ngerin.
Figure 2 The
location of the moorings (and other data streams) for SAIMOS. The pink
circles S1, S2, and S3 denote sea level (CTD) recorders. The current
meter moorings are denoted M1 to M6.
SAIMOS has recently been extended to the
Bonney Coast and will include HF RADAR, gliders and acoustic curtains
for tagged fish. The Victorian agencies MAFRI and the EPA are
participating in these developments and the EPA (Randall Lee) has
equipped the Bass Strait ferry (Spirit of Tasmania) with automated
sampling equipment for ocean temperature, salinity and fluorescence.
John Middleton, Guennady Platov, Mauro Cirano and
John Bye
Over the last two decades, my research has focused
on understanding the weather-band ocean circulation over continental
shelves. Particular areas of study involve the generation and scattering
of coastal-trapped waves by variations in shelf geometry, and by large
sea straits as typified by Bass Strait. Indeed, a reasonably complete
scattering theory has been developed for sea straits, and numerical
models developed to describe the circulation for the Bass Strait region.
Through numerical model development and analyses of data, we have also
made advances in understanding the circulation along Australia ’s continental southern shelves and the
upwelling system off South
Australia . Highlights include advances in
understanding the fundamental processes of upwelling, the identification
of the Flinders Current as a small sister to the world’s great western
boundary currents, and the determination that El Nino signals have led
to more effective upwelling off
S.A.
In addition, we have shown why downwelling occurs throughout the year in
the western GAB as an explanation of the low primary productivity of the
region.
A comprehensive review paper on the circulation
along Australia's southern shelves (Middleton and Bye 2007) has been
published. See publication list
Click on this link for information on the Circulation along Australia's Southern Shelves.
The South Australian
Regional Ocean Model (SAROM I, 2004): $40K, FRDC
John Middleton, Guennady Platov
Funding was obtained to develop a proto-type hind-cast model for the
ocean circulation and upwelling off Kangaroo Is. The model developed was
able to reproduce variations in sea level as well as the upwelled plumes
of cold nutrient rich water as shown in Figure 1 above. The inability of
the model to reproduce some aspects of the upwelled circulation led me
to discover that (summer) El Nino events can act to raise the
thermocline by 100-150m, so that colder, nutrient rich water is closer
to the surface during summer. See
publication list
Ocean Circulation
within Spencer Gulf and connectivity to the adjacent shelf (2006-2010):
$200K, CNpq
Carlos Teixeira (PhD student), John Middleton
This project seeks to determine the circulation in SG that arises
from (i) tidal forcing, (ii) winds (3-20 d variability), (iii) incident
CTWs and (iv) density variations driven by atmospheric heating and
evaporation. Parts (i)-(iii) are near complete and we are able to
explain why the wind (and CTW) forcing generally result in relatively
weak currents (< 5 cm/s) within the gulf: tidal currents are up to 50
cm/s. An additional result is that the wind driven (and not tidal)
currents are important to larval/nutrient dispersal since they persist
over times (3-20 d) much longer than the diurnal tides.
The last component of the project will look at the density driven
currents and interaction with those that arise from the upwelled water
on the adjacent shelf. The hypothesis that the upwelled water shelf
water blocks the exit of dense SG water onto the shelf will be examined.
To examine this, a circulation model will
in the first instance be driven by a
"typical" October to May climatology of atmospheric forcing: the latter
will typify weather-band forcing (3-20 d) for the region as well as
monthly forcing averages. In this way a typical ocean circulation will
be reconstructed that can be evaluated against extant and SAIMOS data
and SG/shelf exchange (or lack of \) can be examined.
A
Hydrodynamic/Biochemical Modelling Facility for S.A. (2008-2011): $286K,
MISA
John Middleton, Laurent Seuront, Charles
James, John Luick, Sophie Leterme, Carlos Teixeira, Leeying Wu
The hydrodynamic model (SAROM II)
will build upon SAROM I and the SG studies above but extend from
Thevenard to Cape Otway (Bass Strait). Again, in the first instance be
driven by a "typical" October to May climatology of atmospheric forcing:
the latter will typify weather-band forcing (3-20 d) for the region as
well as monthly forcing averages. In this way a typical ocean
circulation will be reconstructed. The model will subsequently be
embedded in output from the (global) CSIRO Bluelink model and hind-cast
skill developed for the SAIMOS period of intense observations (October
2008-April 2011).
In addition, we will couple the
ocean model to a Nitrogen, Phytoplankton Zooplankton (NPZ) biochemical
model. In the first instance, a simplified geometry will be adopted to
examine the inter-relationship between time/space scales of upwelling
and NPZ. Subsequently, the NPZ model will be calibrated against the
SAIMOS (and other) data for the Kangaroo Is ecosystem.
The SAROM II facility will when
finished
enable us to quantify the link between ocean
circulation and the space-time dynamics of the plankton ecosystem for
shelf and gulf systems. In addition, the facility will allow for the
prediction of the transport of sediments and their interaction with
marine life and impact on coastal morphology. This facility will also
enable service provision to areas including aquaculture, prawn and
lobster larval dispersion and recruitment, virus spread, impacts of
desalination plants, sewage outfalls and sediment/sand transport.
Optimising the Prawn Harvest in Spencer Gulf: a biophysical management
tool (2008-2010): $300K, FRDC
Cameron Dixon, John Middleton
This project seeks to determine
where and when adult prawns may be taken from SG so as to optimise the
pre-Christmas prawn catch in a sustainable manner. The project will use
spatial/temporal prawn spawning data from SG and a coupled ocean/larval
model to determine the connectivity between spawning grounds and the
recruitment grounds in the coastal mangroves of NW Spencer Gulf.
Student and Research projects
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