i Southeast Queensland Storm Tide Response to Ex. Tropical Cyclone Oswald Reference: Report_Final.docx Date: November 2015 Mitchell Smith W0071559 Tropical Cyclone Oswald Tropical Cyclone Oswald ii Abstract Although a significant body of work exists, previous storm tide studies within Moreton Bay have consistently underestimated observed peak tide gauge levels by up to 40%. There remains scientific debate regarding the source of this “missing” contribution, which is hypothesised to be resultant from either disturbance of regional oceanic density structure, wave radiation stress gradients due to wave breaking on the Spitfire Banks or the need to improve the current parameterisation of wind stress into the water column. To support or disprove these hypotheses, this study investigates the regional surge response during the passage of Ex. Tropical Cyclone Oswald in January 2013 through the application of a series of integrated hydrodynamic and spectral wave modelling experiments. Overall, the shape and magnitude of the experiments with wave radiation stresses activated provide a better match (~27% peak underestimate) to measured residuals compared with tide plus surge only experiments (~47% underestimate) supporting the theory of wave-surge interaction. During the twenty-hour period of greatest wind speeds however, there is a consistent ~25% underestimation that tends to support a call to improve the implementation of model physics at the air-sea interface, while the effects of 3D regional ocean contributions needs to be revisited when improved model boundaries are available and this aspect cannot be dismissed. Tropical Cyclone Oswald iii Contents Limitations of Use The Council of the University of Southern Queensland, its Faculty of Health, Engineering & Sciences, and the staff of the University of Southern Queensland, do not accept any responsibility for the truth, accuracy or completeness of material contained within or associated with this dissertation. Persons using all or any part of this material do so at their own risk, and not at the risk of the Council of the University of Southern Queensland, its Faculty of Health, Engineering & Sciences or the staff of the University of Southern Queensland. This dissertation reports an educational exercise and has no purpose or validity beyond this exercise. The sole purpose of the course pair entitled “Research Project” is to contribute to the overall education within the student’s chosen degree program. This document, the associated hardware, software, drawings, and other material set out in the associated appendices should not be used for any other purpose: if they are so used, it is entirely at the risk of the user. Tropical Cyclone Oswald iv Contents Candidate Certification I certify that the ideas, designs and experimental work, results, analysis and conclusions set out in this dissertation are entirely my own efforts, except where otherwise indicated and acknowledged. I further certify that the work is original and has not been previously submitted for assessment in any other course or institution, except where specifically stated. Mitchell James Smith Student Number W0071559 2nd of November, 2015. Tropical Cyclone Oswald v Contents Acknowledgements The author would like to acknowledge and thank the following for their assistance and advice during completion of the project: Dr Md Jahangir Alam - Primary Supervisor - University of Southern Queensland Dr Bruce Harper - External Supervisor - Systems Engineering Australia Dr Ian Teakle - External Supervisor – BMT-WBM Mr Toby Devlin – BMT-WBM Dr Matthew Barnes – BMT-WBM Dr Jason McConochie – Shell, The Hauge Dr Dave Callaghan - University of Queensland The author would also like to thank the on-going work of the following organisations, which without the data they collect and provide it would not have been possible to complete studies such as this. The Queensland Department of Science, Information Technology, Innovation and the Arts; Maritime Safety Queensland; Manly Hydraulics Laboratory; The Bureau of Meteorology; and The U.S National Centre for Environmental Prediction. Tropical Cyclone Oswald vi Contents Contents Abstract ................................................................................................................................................ ii Limitations of Use ................................................................................................................................ iii Candidate Certification ........................................................................................................................ iv 1 Introduction ................................................................................................................ 11 1.1 Outline ............................................................................................................................... 11 1.2 The Problem ..................................................................................................................... 11 1.3 Tropical Cyclone Oswald ................................................................................................ 12 1.4 Research Objectives ........................................................................................................ 14 1.5 Report Summary .............................................................................................................. 15 2 Literature Review ....................................................................................................... 17 2.1 Physical Processes ......................................................................................................... 17 2.1.1 Introduction .................................................................................................................. 17 2.1.2 Overview of Storm Tide Components ......................................................................... 18 2.1.3 Equations of Motion ..................................................................................................... 19 2.1.4 Surface Wind and Pressure ........................................................................................ 21 2.1.4.1 Tropical Cyclones ............................................................................................................... 21 2.1.4.2 East Coast Lows ................................................................................................................. 25 2.1.4.3 Sub-Tropical, Extra-Tropical and Hybrid Systems ............................................................. 25 2.1.5 Astronomical Tide ........................................................................................................ 26 2.1.6 Bathymetry and Coastal Morphology .......................................................................... 28 2.1.7 Storm Surge ................................................................................................................ 30 2.1.8 Surface Wind Waves ................................................................................................... 30 2.1.9 Limitations in our current understanding of wave-surge physics ................................. 32 2.1.10 Ocean Vertical Structure .......................................................................................... 32 2.1.11 Oceanic Long Waves ............................................................................................... 34 2.1.11.1 Kelvin Waves ...................................................................................................................... 35 2.1.11.2 Rossby Waves .................................................................................................................... 36 2.1.12 Internal Waves ......................................................................................................... 36 2.2 Review of Recent Local Storm Tide Investigation ........................................................ 37 2.2.1 Moreton Bay and Logan/Redland Storm Tide Study ................................................... 38 2.2.2 Tropical Cyclone Rodger (Stewart, Callaghan & Nielsen 2010) .................................. 39 2.2.3 Gold Coast Storm Tide Study ...................................................................................... 40 2.2.4 Brisbane Coastal Planning and Implementation Study. .............................................. 41 2.2.5 Callaghan et al. (2012) ................................................................................................ 41 2.3 Other Relevant Literature ................................................................................................ 42 3 Research Methodology ............................................................................................. 44 4 Data Collation ............................................................................................................. 46 4.1 Bathymetry and Topography .......................................................................................... 46 4.2 Meteorological Data ......................................................................................................... 46 4.2.1 Synoptic Observations ................................................................................................ 46 4.2.2 ACCESS and CFSv2 ................................................................................................... 46 4.3 Gridded Ocean Data .......................................................................................................