Current state of ECHAM5/NEMO coupled model

Wonsun Park, Noel Keenlyside, Mojib Latif (IFM-GEOMAR)

René Redler (NEC C&C Research Laboratories)

DRAKKAR meeting25-26 January 2007, Grenoble, France

Outline

• Overview of the coupled model• 500-yr long simulations• Current state• Summary and outlook

Overview of KCM

• Kiel Climate Model (KCM): ECHAM5/NEMO coupled model

• Component models– AGCM: ECHAM5 (T31L19, T63L31,

T106L31), IPCC version– OGCM: NEMO (ORCA2 standard, ORCA05-

DRAKKAR configuration), V1_12, NEMO2– Coupler: OASIS3 or OASIS4 within PRISM

Two 500-yr experiments

• Same ORCA2 configuration– NEMO v1_12– Standard parameters– LIM parameters (hiccrit=0.3,0.6; angvg=-15)

• Different ECHAM5 tuning parameters– T31L19 resolution– P53: IPCC cloud scheme and parameters– P57: New cloud scheme (Tompkins, 2002)

MOC 30N

Drake passage

P57 New cloud scheme

P53 IPCC parameters

15

13

11

9

7160

140

120

100

80

60

Transport (11-yr runavg)15

13

11

9

7160

140

120

100

80

60

TOA Radiation & 2m-temp

1.5

1.0

0.5

[W/m2]

P53 IPCC parameters

P57 New cloud scheme

SST biases

P57 New cloud scheme P53 IPCC parameters

Nino3 spectra

51mn 34mn

Equatorial annual cyclesObservation New cloud IPCC parameters

Sea iceIce area [106 km2]

Fraction [%], March

Thickness [m], March

angvg=-25 angvg=25

Ice dynamics test

T25 ang=0 no islands

• Adopting turning angle of ice drift

• Removing island?

• Canadian archipelago: hydrological model change , redigitizing?

Current coupling scheme • NEMO2 • Separate choice of angvg for NH and SH• Preliminary hydrological model tuning in ECHAM5

concerning Canadian archipelago (need further investigation for changing mask in ORCA2?)

• All Albedos unified in ECHAM5 (sea ice as well) • Coupling time step: 1x, 4x, 12x/day• Variable exchanged

– Ocean to atmosphere (7): SST, sea ice fraction, sea ice thickness, snow thickness, sea ice temperature, zonal-, meridional- ocean velocity

– Atmosphere to ocean (11): U-, V- wind stresses on u- and v-grids, total P-E, solid P-E, solar- and non-solar heat flux over water and ice, non-solar heat flux derivative

Current run

13Sv

1 yr 150

MOC 30N

Ice area

Ice cover and thickness

Ongoing analysis• Tropical variability from ECHAM5/NEMO

coupled model (Paper in preparation)• ENSO and MOC relationship on

multidecadal scales• Freshwater variability and MOC (with

comparison to T42, T63 atmosphere)

• Comparison with existing standalone ORCA2 simulations

Summary and outlook• KCM prototype is available for coordinated

experiments with standalone NEMO • Two 500-yr long simulations with difference

atmosphere configurations:– Stable climate ( <1 W/m2 TOA net radiation)– Importance of atmosphere forcing to ENSO spectra– Still low MOC, cold bias over North Atlantic

• YR2007: Constructing higher resolution model– ECHAM5 T63L31/T106L31 coupled to ORCA05

DRAKKAR configuration, OASIS4– Standalone ECHAM5, NEMO, and coupled model

experiments following scientific interests

Thanks

Mixed layer depth

Previous (P57) Current

Meridional Overturning Circulation & Antarctic Circumpolar Current

P53

J64

MOC

ACC

9Sv

95Sv

13Sv

110Sv