A First Generation Dynamical Tropical Cyclone Storm Surge Forecast System Part 1: Hydrodynamic model Diana Greenslade, Andy Taylor, Justin Freeman, Holly Sims, Eric Schulz, Frank Colberg, Prasanth Divakaran, Mirko Velic and Jeff Kepert October 2018 Bureau Research Report - 031 A FIRST GENERATION DYNAMICAL TROPICAL CYCLONE STORM SURGE FORECAST SYSTEM PART 1: HYDRODYNAMIC MODEL A FIRST GENERATION DYNAMICAL TROPICAL CYCLONE STORM SURGE FORECAST SYSTEM PART 1: HYDRODYNAMIC MODEL A First Generation Dynamical Tropical Cyclone Storm Surge Forecast System Part 1: Hydrodynamic model Diana Greenslade, Andy Taylor, Justin Freeman, Holly Sims, Eric Schulz, Frank Colberg, Prasanth Divakaran, Mirko Velic and Jeff Kepert Bureau Research Report No. 031 October 2018 National Library of Australia Cataloguing-in-Publication entry Author: Diana Greenslade, Andy Taylor, Justin Freeman, Holly Sims, Eric Schulz, Frank Colberg, Prasanth Divakaran, Mirko Velic and Jeff Kepert Title: A First Generation Dynamical Tropical Cyclone Storm Surge Forecast System Part 1: Hydrodynamic model ISBN: 978-1-925738-08-7 Series: Bureau Research Report – BRR031 Page i A FIRST GENERATION DYNAMICAL TROPICAL CYCLONE STORM SURGE FORECAST SYSTEM PART 1: HYDRODYNAMIC MODEL Enquiries should be addressed to: Diana Greenslade: Bureau of Meteorology GPO Box 1289, Melbourne Victoria 3001, Australia [email protected]: Copyright and Disclaimer © 2016 Bureau of Meteorology. To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of the Bureau of Meteorology. The Bureau of Meteorology advise that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law and the Bureau of Meteorology (including each of its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Page ii A FIRST GENERATION DYNAMICAL TROPICAL CYCLONE STORM SURGE FORECAST SYSTEM PART 1: HYDRODYNAMIC MODEL Contents ABSTRACT ................................................................................................................. 1 1. Introduction ....................................................................................................... 2 2. Other operational storm surge forecast systems ........................................... 4 3. Surface forcing .................................................................................................. 6 4. Hydrodynamic modelling.................................................................................. 9 4.1 Model configuration ................................................................................................ 10 4.2 Offshore territories .................................................................................................. 11 4.3 Subsetted domain ................................................................................................... 13 4.4 Wave set-up ............................................................................................................ 14 5. Verification ...................................................................................................... 15 5.1 Observations ........................................................................................................... 16 5.2 Summary of Performance ....................................................................................... 17 5.3 Case Study results .................................................................................................. 20 5.3.1 TC Anthony ......................................................................................................... 20 5.3.2 TC Yasi ............................................................................................................... 22 5.3.3 TC Ita .................................................................................................................. 25 5.3.4 TC Lam ............................................................................................................... 28 5.3.5 TC Marcia ........................................................................................................... 29 5.3.6 TC Olwyn ............................................................................................................ 31 5.3.7 TC Nathan .......................................................................................................... 33 5.4 Comparison with existing systems ......................................................................... 34 6. Further Work ................................................................................................... 38 7. Acknowledgements......................................................................................... 40 8. References ....................................................................................................... 41 Page iii A FIRST GENERATION DYNAMICAL TROPICAL CYCLONE STORM SURGE FORECAST SYSTEM PART 1: HYDRODYNAMIC MODEL List of Figures Fig. 1 Velocity magnitude and velocity vectors from Best Track data for TC Yasi on 2 February 2011 at 0400 UTC. The calculated velocity field includes storm forward motion, friction and inflow angle correction. .............................................................................................. 8 Fig. 2 Domain of the full tropical grid. This is subsetted for each run. ..................................... 10 Fig. 3 Spatial extents of all grids tested for Christmas Island, with a snapshot of storm surge height at 3:00 UTC on 22nd March 2014 from TC Gillian overlaid. ............................... 12 Fig. 4 Time series of maximum value of sea level in each grid. ............................................... 13 Fig. 5 Best Tracks for the seven events examined................................................................... 16 Fig. 6 Hourly fixes of the Best Track for TC Anthony (light blue crosses) and location of 3 tide gauges (red diamonds) used for verification .................................................................. 20 Fig. 7 Left hand panel shows the location of the Bowen tide gauge (green pin) in relation to the local coastline and the model's coastal grid points (white circles). The closest grid point is indicated by the red circle. Right hand panel shows de-tided Bowen station data (black diamonds) during TC Anthony compared with the model hindcast at the closest grid point. Blue line is surge only, green line is wave set-up and red line is surge + wave set-up. 21 Fig. 8 Same as Fig. 7 but for Shute Harbour ............................................................................ 21 Fig. 9 Same as Fig. 7 but for Laguna Quays ............................................................................ 21 Fig. 10 Hourly fixes of the Best Track for TC Yasi (blue crosses) and location of the 6 tide gauges (red diamonds) used for verification ............................................................................... 22 Fig. 11 Left hand panel shows the location of the Cairns tide gauge (green pin) in relation to the local coastline and the model's coastal grid points (white circles). The closest grid point is indicated by the red circle. Right hand panel shows de-tided Cairns station data (black diamonds) during TC Yasi compared with the model hindcast at the closest grid point. Blue line is surge only, green line is wave set-up and red line is surge + wave set-up. 23 Fig. 12 Same as Fig. 11 but for Mourilyan .................................................................................. 23 Fig. 13 Same as Fig. 11 but for Clump Point .............................................................................. 23 Fig. 14 Same as Fig. 11 but for Cardwell ................................................................................... 24 Fig. 15 Same as Fig. 11 but for Townsville ................................................................................ 24 Fig. 16 Same as Fig. 11 but for Cape Ferguson ........................................................................ 24 Fig. 17 Hourly fixes of the Best Track for TC Ita (green crosses) and location of the 6 tide gauges (red diamonds) used for verification. .............................................................................. 25 Fig. 18 Left hand panel shows the location of the Cooktown tide gauge (green pin) in relation to the local coastline and the model's coastal grid points (white circles). The closest grid point is indicated by the red circle. Right hand panel shows de-tided Cooktown station data (black diamonds) during TC Ita compared with the model hindcast at the closest grid point. Blue line is surge only, green line is wave set-up and red line is surge + wave set- up. 26 Fig. 19 Same as Fig. 18 but for Cairns ....................................................................................... 26 Fig. 20 Same as Fig. 18 but for Cardwell ..................................................................................