Hobart

Seminar Abstract

Friday 27 June 2008, 11.30am (Tas time)
CSIRO *Conference Rooms A & B*, Hobart

Mark Hemer
Postdoctoral Fellow, CAWCR
CSIRO Marine and Atmospheric Research

Variability and trends of the directional wave climate in the Australian region

Changes in wave climate, in response to climate change driven variations of atmospheric circulation, are of interest from many perspectives, particularly in the coastal zone. Potential impacts include: erosion via shifts in wave direction altering coastal sediment budgets and the effects of wave run-up; inundation in response to the combined action of wave set-up/run-up, storm-surges and sea-level rise; and disturbance to near-shore aquatic and terrestrial habitats via wave driven bed shear stresses.

Available wave data, from in-situ waverider buoys, satellite altimeters, and global and regional wave models, have been used to describe the existing directional wave climate in the Australian region. Inter-annual variability and trends in the directional wave climate have been determined, and dominant modes of variability identified using EOF analyses. The principal mode of variability in the directional wave climate displays significant correlation with the Southern Annular Mode Index (SAMI), particularly during the Austral Autumn and Winter months. Increased wave heights and anti-clockwise rotation of wave direction in the Southern Ocean are associated with positive anomalies of the SAMI. Correlation between wave climate and the Southern Oscillation Index is observed in the Pacific Basin consistent with prior coastal studies.

To confirm the variability recorded in the global wave model datasets, an independent analysis was carried out, wherein synoptic types associated with large wave events, observed in the ~10-yr waverider buoy record, were identified in the NCEP-NCAR re-analysis and ERA-40 re-analysis MSLP record. The occurrence of these synoptic types was tallied for the full re-analyses records, and a significant positive correlation between the frequency of large wave generating storms and the SAMI is observed.

Long-term monitoring of shoreline has been carried out at only a few locations, and consequently little to no observed record of any coastal response to such wave variability is available. Near-shore wave models are being run to estimate the impacts of observed offshore variability on the near-shore wave climate, and consequent erosion/accretion regimes, in an effort to stimulate interest in long-term coastal monitoring programs.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Bernadette Sloyan, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5152
Thomas Kunz, (Biological seminars) CSIRO Marine and Atmospheric Research
(03) 6232 5076
Natalie Dowling, (Fisheries Modelling) CSIRO Marine and Atmospheric Research
(03) 6232 5148
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 21/07/09