COAWST 2014

Scenarios of future changes in the occurrence of Scenarios of future changes in the occurrence of extreme storm surges – an application of extreme storm surges – an application of

COAWST to COAWST to Southwest Pacific ocean regionSouthwest Pacific ocean region

André Paul Mark HadfieldMichael Schulz

Nilima Natoo

28th August 2014

Special thanks toStefan Jendersie

John C WarnerJanet Bornman

Willem de Lange

COAWST 2014

OutlineOutline

• South Pacific Ocean region

• Objectives

• Methodology

• Results

• Outlook

COAWST 2014

OutlineOutline

• South Pacific Ocean region

• Objectives

• Methodology

• Results

• Outlook

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 regionSouth Pacific Ocean region

©Petchey et al. (2008)

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 regionSouthwest Pacific Ocean region

COAWST 2014

Regional extent and bathymetryRegional extent and bathymetry

m

Chatham Rise

Tasm

an A

bys

sal P

lain

Kar

mad

ec R

idge

Tonga R

idge

Great Barrier Reef

New Caledonia

Colv

ille R

idge

Lau

Rid

ge

L

ord

How

e

Ris

e

N

ew

Cale

donia

Tro

ugh N

orf

olk

Ris

e

North Cape

Norf

olk

Basi

n

Thre

e K

ings

Ris

e

FijiVanuatu

Challenger Plateau

Hikur

angi

Tro

ugh

COAWST 2014

OutlineOutline

• Southwest Pacific Ocean region

• Objectives

• Methodology

• Results

• Outlook

COAWST 2014

ObjectivesObjectives

Are any significant changes in mean storminess to be expected by the end of the 21st century?

Does regional ocean-atmosphere coupling help to improve the predictability of mean storminess during the 21st century?

COAWST 2014

OutlineOutline

• Southwest Pacific Ocean region

• Objectives

• Methodology

• Results

• Outlook

COAWST 2014

Methodology – global model dataMethodology – global model data

COAWST 2014

MethodologyMethodology

- at least 3 ensemble members

- archived most of the variables

- atmospheric data available at higher temporal resolution

- literature review

IPSL_CM5A_LRSelection of global model (from cmip5 suit of models)

Basic criteria of model selection

COAWST 2014

Methodology – global model dataMethodology – global model data

IPSL_CM5A_LR global model data(source: http://icmc.ipsl.fr/index.php/icmc-models/icmc-ipsl-cm5)

COAWST 2014

MethodologyMethodology

- at least 3 ensemble members

- archived most of the variables

- atmospheric data available at higher temporal resolution

- literature review

IPSL_CM5A_LRSelection 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

COAWST 2014

MethodologyMethodology

Experimental Set-up

Boundary conditions

Ensemble members

Time-slices

Control run (historical)

r1i1p1 1960-1964

r2i1p1

r3i1p1

Scenario run(RCP 8.5)

r1i1p1 2095-2099

r2i1p1

r3i1p1

ROMS onlyWRF onlyWRF-ROMS coupled

Total experiments =3 (model combinations) x 3 (ensemble members) x 2 time-slices (his and rcp) = 18

COAWST 2014

Uncoupled WRF Uncoupled ROMS

Time-step (s) 90 180

No. of layers 32 (depth or s_rho) 34 (eta_levels)

Initial condition Jan 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 data Terrain data: 10 min Bathymetry data: ETOPO 1

MethodologyMethodology

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)Methodology – surface forcing (cppdefs.h)

#define WRF_MODEL

Uncoupled WRF

COAWST 2014

OutlineOutline

• Southwest Pacific Ocean region

• Objectives

• Methodology

• Results (ROMS only)

• Outlook

COAWST 2014

Results: 5-year mean SSH and surface current velocityResults: 5-year mean SSH and surface current velocityC

ontr

ol

Sce

nari

oD

iffere

nce

m

Summer (DJF) (Autumn) MAM Winter (JJA) (Spring) SON

COAWST 2014

Results: 5-year mean surface wind velocityResults: 5-year mean surface wind velocityC

ontr

ol

Sce

nari

oD

iffere

nce

m/s

Summer (DJF) (Autumn) MAM Winter (JJA) (Spring) SON

COAWST 2014

Results: 5-year mean surface air pressureResults: 5-year mean surface air pressureC

ontr

ol

Sce

nari

oD

iffere

nce

mb

mb

Summer (DJF) (Autumn) MAM Winter (JJA) (Spring) SON

COAWST 2014

Results: 5-year mean sea surface temperatureResults: 5-year mean sea surface temperatureC

ontr

ol

Sce

nari

oD

iffere

nce

°C

°C

Summer (DJF) (Autumn) MAM Winter (JJA) (Spring) SON

COAWST 2014

OutlineOutline

• Southwest Pacific Ocean region

• Objectives

• Methodology

• Results (ROMS only)

• Outlook

COAWST 2014

OutlookOutlook

o ROMS only result analysis

o Coupled simulations

o WRF only simulations

o WRF only result analysis

o Comparison with coupled model results

COAWST 2014