1. COAWST 2014 Scenarios of future changes in the occurrence of extreme storm surges – an application of COAWST to Southwest Pacific ocean region André Paul Mark Hadfield Michael Schulz Nilima Natoo 28 th August 2014 Special thanks to Stefan Jendersie John C Warner Janet Bornman Willem de Lange

2. COAWST 2014 Outline South Pacific Ocean region Objectives Methodology Results Outlook

3. COAWST 2014 Outline South Pacific Ocean region Objectives Methodology Results Outlook

4. COAWST 2014 Prominent currents of importance: –SEC South equatorial current (north and south branches) –EAC East Australian Current –NGCC New Guinea coastal current –STCC Subtropical counter current –ACC Antarctic counter current Other local currents: –NVJ North Vanuatu Jet –SVJ South Vanuatu jet –NCJ North Caledonian jet –SCJ South Caledonia jet South Pacific Ocean region ©Petchey et al. (2008)

5. COAWST 2014 Prominent currents and eddies of importance: - EAUC East Auckland Current - ECC East Cape Current - TF Tasman Front - SC Southland Current - NCE North Cape Eddy - ECE East Cape Eddy - WE Wairarapa Eddy Southwest Pacific Ocean region

6. COAWST 2014 Regional extent and bathymetry m Chatham Rise Tasman Abyssal Plain Karmadec Ridge Tonga Ridge Great Barrier Reef New Caledonia Colville Ridge Lau Ridge Lord Howe Rise New Caledonia Trough Norfolk Rise North Cape Norfolk Basin Three Kings Rise Fiji Vanuatu Challenger Plateau Hikurangi Trough

7. COAWST 2014 Outline Southwest Pacific Ocean region Objectives Methodology Results Outlook

8. COAWST 2014 Objectives Are any significant changes in mean storminess to be expected by the end of the 21 st century? Does regional ocean-atmosphere coupling help to improve the predictability of mean storminess during the 21 st century?

9. COAWST 2014 Outline Southwest Pacific Ocean region Objectives Methodology Results Outlook

10. COAWST 2014 Methodology – global model data

11. COAWST 2014 Methodology -at least 3 ensemble members -archived most of the variables -atmospheric data available at higher temporal resolution -literature review IPSL_CM5A_LR Selection of global model (from cmip5 suit of models) Basic criteria of model selection

12. COAWST 2014 Methodology – global model data IPSL_CM5A_LR global model data (source: http://icmc.ipsl.fr/index.php/icmc-models/icmc-ipsl-cm5)

13. COAWST 2014 Methodology -at least 3 ensemble members -archived most of the variables -atmospheric data available at higher temporal resolution -literature review IPSL_CM5A_LR Selection of global model (from cmip5 suit of models) Basic criteria of model selection IPSL_CM5A_LR global model data Ocean = 2.0° x 2.0° x 31L (~0.5° near equator) Atmosphere = 1.9° x 3.75° x 39L Interpolated on to SP14 region ROMS model ~ 0.25° x 0.25° x 32L WRF model ~ 0.25° x 0.25° x 34L

14. COAWST 2014 Methodology Experimental Set-up Boundary conditions Ensemble members Time-slices Control run (historical) r1i1p11960-1964 r2i1p1 r3i1p1 Scenario run (RCP 8.5) r1i1p12095-2099 r2i1p1 r3i1p1 ROMS only WRF only WRF-ROMS coupled Total experiments =3 (model combinations) x 3 (ensemble members) x 2 time-slices (his and rcp) = 18

15. COAWST 2014 Uncoupled WRFUncoupled ROMS Time-step (s)90180 No. of layers32 (depth or s_rho)34 (eta_levels) Initial conditionJan 1960 (wrfinput_d01.nc) Jan 1960 (roms_ini.nc) lateral boundary forcing@ 3 hourly (wrfbdy_d01.nc) @ monthly (roms_bdy.nc) surface forcing - @ 3 hourly (roms_frc.nc) Other dataTerrain data: 10 minBathymetry data: ETOPO 1 Methodology

16. COAWST 2014 #define BULK_FLUXES #define LONGWAVE_OUT #define EMINUSP #define SOLAR_SOURCE #define COOL_SKIN Uncoupled ROMS #define WRF_MODEL #ifdef WRF_MODEL #define MCT_LIB #undef BULK_FLUXES #define ATM2OCN_FLUXES #endif #define LONGWAVE_OUT #define EMINUSP #define SOLAR_SOURCE #define COOL_SKIN Coupled WRF-ROMS Methodology – surface forcing (cppdefs.h) #define WRF_MODEL Uncoupled WRF

17. COAWST 2014 Outline Southwest Pacific Ocean region Objectives Methodology Results (ROMS only) Outlook

18. COAWST 2014 Results: 5-year mean SSH and surface current velocity Control Scenario Difference m Summer (DJF)(Autumn) MAM Winter (JJA) (Spring) SON

19. COAWST 2014 Results: 5-year mean surface wind velocity Control Scenario Difference m/s Summer (DJF)(Autumn) MAM Winter (JJA) (Spring) SON

20. COAWST 2014 Results: 5-year mean surface air pressure Control Scenario Difference mb Summer (DJF)(Autumn) MAM Winter (JJA) (Spring) SON

21. COAWST 2014 Results: 5-year mean sea surface temperature Control Scenario Difference °C Summer (DJF)(Autumn) MAM Winter (JJA) (Spring) SON

22. COAWST 2014 Outline Southwest Pacific Ocean region Objectives Methodology Results (ROMS only) Outlook

23. COAWST 2014 Outlook o ROMS only result analysis o Coupled simulations o WRF only simulations o WRF only result analysis o Comparison with coupled model results

24. COAWST 2014