Guide to Storm Surge Forecasting GUIDE TO STORM SURGE FORECASTING P-WDS_11671 WMO-No. 1076 www.wmo.int WMO-No. 1076 Guide to Storm Surge Forecasting WMO-No. 1076 2011 edition WMO-No. 1076 © World Meteorological Organization, 2011 The right of publication in print, electronic and any other form and in any language is reserved by WMO. Short extracts from WMO publications may be reproduced without authorization, provided that the complete source is clearly indicated. Editorial correspondence and requests to publish, reproduce or translate this publication in part or in whole should be addressed to: Chairperson, Publications Board World Meteorological Organization (WMO) 7 bis, avenue de la Paix Tel.: +41 (0) 22 730 84 03 P.O. Box No. 2300 Fax: +41 (0) 22 730 80 40 CH-1211 Geneva 2, Switzerland E-mail: [email protected] ISBN 978-92-63-11076-3 NOTE The designations employed in WMO publications and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of WMO concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. Opinions expressed in WMO publications are those of the authors and do not necessarily reflect those of WMO. The mention of specific companies or products does not imply that they are endorsed or recommended by WMO in preference to others of a similar nature which are not mentioned or advertised. contents Page foreword ................................................................................................................................................. vii Acknowledgements ............................................................................................................................... ix cHAPter 1. IntrodUctIon And generAl consIderAtIons .............................................................. 1-1 1.1 Oceanographical aspects of storm surges .......................................................................................... 1-1 1.2 Meteorological aspects of storm surges ............................................................................................. 1-3 1.3 Methods of storm surge prediction – an overview ............................................................................. 1-3 1.4 Empirical methods for surge prediction ............................................................................................. 1-4 1.5 Statistical methods ............................................................................................................................ 1-5 1.6 Storm surge prediction through artificial neural networks .................................................................. 1-6 1.6.1 Artificial neural networks ................................................................................................... 1-6 1.6.2 Optimal ANN modelling ................................................................................................... 1-7 1.6.3 Regional real-time storm surge prediction system for three stations in the Republic of Korea ............................................................................................................. 1-8 1.7 Numerical methods ........................................................................................................................... 1-9 cHAPter 2. storm sUrge PHYsIcs .......................................................................................................... 2–1 2.1 Meteorological effects ....................................................................................................................... 2-1 2.2 Oceanographical effects .................................................................................................................... 2-3 2.3 Hydrographical effects ....................................................................................................................... 2-3 2.4 Seiches .............................................................................................................................................. 2-4 2.5 Tide–surge interaction ....................................................................................................................... 2-5 2.6 Surge–river interaction ...................................................................................................................... 2-6 2.7 Interaction between surge, wind waves and wave set-up .................................................................. 2-6 2.8 Influence of sea ice on storm surges .................................................................................................. 2-6 2.9 Bottom friction .................................................................................................................................. 2-8 cHAPter 3. BAsIc eQUAtIons And solUtIons ..................................................................................... 3–1 3.1 Formulation of the storm surge equations ......................................................................................... 3-1 3.2 Finite differencing of the time derivative ............................................................................................ 3-2 3.3 Computational stability and CFL criterion .......................................................................................... 3-3 3.4 Staggered and non-staggered grid schemes ...................................................................................... 3-3 3.5 Treatment of the non-linear advective terms...................................................................................... 3-4 3.6 Treatment of open boundaries .......................................................................................................... 3-5 3.7 Treatment of complex coastal boundries ........................................................................................... 3-5 3.8 Moving-boundary models, inclusion of tidal flats and coastal inundation .......................................... 3-6 3.9 Unstructured grids (finite element and finite volume models) ............................................................ 3-7 3.9.1 Finite element methods .................................................................................................... 3-7 3.9.2 Finite volume methods ..................................................................................................... 3-8 3.10 Mesoscale forcing .............................................................................................................................. 3-8 3.11 Remote forcing ................................................................................................................................. 3-9 cHAPter 4. InPUt And oUtPUt PArAmeters ........................................................................................ 4–1 4.1 Introduction ...................................................................................................................................... 4-1 4.2 Model set-up ..................................................................................................................................... 4-1 4.2.1 Bathymetry and geometry ................................................................................................ 4-1 4.2.2 Tidal boundaries ............................................................................................................... 4-1 4.2.3 Data for tuning and calibration ......................................................................................... 4-2 iv GUIDE TO STORM SURGE FORECASTING Page 4.3 Using the model ................................................................................................................................ 4-3 4.3.1 Meteorological input ........................................................................................................ 4-3 4.3.1.1 Meteorological input for a tropical cyclone ..................................................... 4-3 4.3.1.2 Interpolation issues for numerical models ........................................................ 4-4 4.3.2 Hydrological input ............................................................................................................ 4-4 4.4 Validation and verification ................................................................................................................. 4-5 4.5 Output parameters ............................................................................................................................ 4-5 4.5.1 Time series ........................................................................................................................ 4-5 4.5.2 Fields ................................................................................................................................ 4-6 4.5.3 Output from other models ............................................................................................... 4-6 4.5.4 Example of a forecast result .............................................................................................. 4-6 cHAPter 5. storm sUrge PredIctIon models .................................................................................... 5–1 5.1 Operational two-dimensional storm surge prediction models ............................................................ 5-1 The rationale of the forecasting system ............................................................................