The East Australian Current, upwellings and downwellings off eastern-most Australia in summer
G. R. Cresswell A D , J. L. Peterson B and L. F. Pender CA CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, Tas. 7001, Australia.
B 3906 South Troost Avenue, Tulsa, OK 74105, USA.
C 65 Cades Drive, Kingston, Tas. 7050, Australia.
D Corresponding author. Email: george.cresswell@csiro.au
Marine and Freshwater Research 68(7) 1208-1223 https://doi.org/10.1071/MF16051
Submitted: 19 February 2016 Accepted: 13 October 2016 Published: 14 December 2016
Journal Compilation © CSIRO Publishing 2017 Open Access CC BY-NC-ND
Abstract
The complex influences of the East Australian Current (EAC) and winds on the waters of the continental shelf were addressed with a ship survey, moored and drifting instruments, satellite images and wind and sea level measurements. The study revealed intrusions of continental slope water reaching the inner continental shelf when the EAC was near the shelf edge and wind stress was near zero or upwelling favourable (northerly). The process was the onshore movement of a southward flowing stream of water originally from the continental slope. One event was captured near Cape Byron and Evans Head when these waters upwelled to the surface. When the wind stress turned northward, it reversed the inner shelf current and drove downwelling. Variations in the wind stress also modulated the strength of the EAC out across the shelf to the upper slope. The strength of the EAC per se varied with a time scale of 2–3 months; these variations decreased in amplitude westward until they were undetectable at the inner shelf. The EAC had a subsurface speed maximum of up to 1.6 m s–1 at 100–150-m depth above the continental slope and was seen to accelerate with both time and distance southward along the 190-km length surveyed by the ship.
Additional keywords: current meters, SeaSoar.
References
Armbrecht, L. H., Roughan, M., Rossi, V., Schaeffer, A. K., Davies, P. L., Waite, A. M., and Armand, L. K. (2014). Phytoplankton composition under contrasting oceanographic conditions: upwelling and downwelling (eastern Australia). Continental Shelf Research 75, 54–67.| Phytoplankton composition under contrasting oceanographic conditions: upwelling and downwelling (eastern Australia).Crossref | GoogleScholarGoogle Scholar |
Brieva, D., Ribbe, J., and Lemckert, C. (2015). Is the East Australian Current causing a marine ecological hot-spot and an important fisheries near Fraser Island, Australia? Estuarine, Coastal and Shelf Science 153, 121–134.
| Is the East Australian Current causing a marine ecological hot-spot and an important fisheries near Fraser Island, Australia?Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC2MXkvF2ksQ%3D%3D&md5=c8acac6d1dd89d1b770987c4245c0b74CAS |
Crooks, A. D. (1960). Coastal hydrological investigations in south-eastern Australia, 1958. Oceanographic station list, Vol. 40, CSIRO Division of Fisheries and Oceanography, Melbourne, Vic., Australia.
Gersbach, G. H., Pattiarachi, C. B., Ivey, G. N., and Cresswell, G. R. (1999). Upwelling on the south-west coast of Australia – source of the Capes Current? Continental Shelf Research 19, 363–400.
| Upwelling on the south-west coast of Australia – source of the Capes Current?Crossref | GoogleScholarGoogle Scholar |
Griffin, D. A., and Middleton, J. H. (1992). Upwelling and internal tides over the inner New South Wales continental shelf. Journal of Geophysical Research 97, 14389–14405.
| Upwelling and internal tides over the inner New South Wales continental shelf.Crossref | GoogleScholarGoogle Scholar |
Halligan, G. H. (1911). The bar harbours of New South Wales. Minutes of Proceedings of the Institution of Civil Engineers 184, 128–148.
Hamon, B. V., Godfrey, J. S., and Greig, M. A. (1975). Relation between mean sea level, current and wind stress on the east coast of Australia. Australian Journal of Marine and Freshwater Research 26, 389–403.
| Relation between mean sea level, current and wind stress on the east coast of Australia.Crossref | GoogleScholarGoogle Scholar |
Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Leetmaa, A., Reynolds, R., Jenne, R., and Joseph, D. (1996). The NCEP/NCAR 40-year reanalysis project. Bulletin of the American Meteorological Society 77, 437–471.
| The NCEP/NCAR 40-year reanalysis project.Crossref | GoogleScholarGoogle Scholar |
Kämpf, J. (2015). Phytoplankton blooms on the western shelf of Tasmania: evidence of a highly productive ecosystem. Ocean Science 11, 1–11.
| Phytoplankton blooms on the western shelf of Tasmania: evidence of a highly productive ecosystem.Crossref | GoogleScholarGoogle Scholar |
Kämpf, J., Doubell, M., Griffin, D., Matthews, R. L., and Ward, T. M. (2004). Evidence of a large seasonal coastal upwelling system along the Southern Shelf of Australia. Geophysical Research Letters 31, L09310.
| Evidence of a large seasonal coastal upwelling system along the Southern Shelf of Australia.Crossref | GoogleScholarGoogle Scholar |
McMillin, L. M., and Crosby, D. S. (1984). Theory and validation of multiple window sea surface temperature technique. Journal of Geophysical Research 89, 3655–3661.
| Theory and validation of multiple window sea surface temperature technique.Crossref | GoogleScholarGoogle Scholar |
Nilsson, C. S., and Tildesley, P. C. (1986). Navigation and re-mapping of AVHRR imagery. In ‘Proceedings of the 1st Australian AVHRR Conference’, 22–24 October 1986, Perth, WA, Australia. (Ed. A. J. Prata.) pp. 286–298. (CSIRO, Division of Groundwater Research: Perth, WA, Australia.)
Oke, P. R., and Middleton, J. H. (2000). Topographically induced upwelling off eastern Australia. Journal of Physical Oceanography 30, 512–531.
| Topographically induced upwelling off eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Oke, P. R., England, M. H., and Middleton, J. H. (2003). On the dynamics of an observed thermal front off central eastern Australia. Journal of Geophysical Research 108, 3106–3117.
| On the dynamics of an observed thermal front off central eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Rochford, D. J. (1972). Nutrient enrichment of East Australian coastal waters: I. Evans Head upwelling. CSIRO Division of Fisheries and Oceanography Technical Paper 33, Melbourne, Vic., Australia.
Rossi, V., Schaeffer, A. K., Wood, J., Galibert, G., Morris, B. D., Sudre, J., Roughan, M., and Waite, A. M. (2014). Seasonality of sporadic physical processes driving temperature and nutrient high-frequency variability in the coastal ocean off southeast Australia. Journal of Geophysical Research – Oceans 119, 445–460.
| Seasonality of sporadic physical processes driving temperature and nutrient high-frequency variability in the coastal ocean off southeast Australia.Crossref | GoogleScholarGoogle Scholar |
Roughan, M., and Middleton, J. H. (2002). A comparison of observed upwelling mechanisms off the east coast of Australia. Continental Shelf Research 22, 2551–2572.
| A comparison of observed upwelling mechanisms off the east coast of Australia.Crossref | GoogleScholarGoogle Scholar |
Schaeffer, A., and Roughan, M. (2015). Influence of a western boundary current on shelf dynamics and upwelling from repeat glider deployments. Geophysical Research Letters 42, 121–128.
| Influence of a western boundary current on shelf dynamics and upwelling from repeat glider deployments.Crossref | GoogleScholarGoogle Scholar |
Schaeffer, A., Roughan, M., and Wood, J. E. (2014). Observed bottom boundary layer transport and uplift on the continental shelf adjacent to a western boundary current. Journal of Geophysical Research – Oceans 119, 4922–4939.
| Observed bottom boundary layer transport and uplift on the continental shelf adjacent to a western boundary current.Crossref | GoogleScholarGoogle Scholar |
UNESCO (1981). Tenth Report of the Joint Panel on Oceanographic Tables and Standards. UNESCO Technical Papers in Marine Science 36, UNESCO, Paris.
Wood, J. E., Schaeffer, A., Roughan, M., and Tate, P. M. (2016). Seasonal variability in the continental shelf waters off southeastern Australia: fact or fiction? Continental Shelf Research 112, 92–103.
| Seasonal variability in the continental shelf waters off southeastern Australia: fact or fiction?Crossref | GoogleScholarGoogle Scholar |
