The Coupler

Jun Wang, Xingren Wu, Jinde Wang, Hua-lu Pan

EMC/NCEP/NOAA

Acknowledge to: Dmitry Sheinin, Yu-tai Hou, Shrinivas Moorthi, Mark Iredell

The Coupled model: MOM4

• Parallel programming model in MOM4: SPMD

ATM+

LAND+

Sea Ice

MOM4.exe

Ocean

GFS-MOM4 CouplerParallel programming model:

MPMD (Multiple Program Multiple Data)

GFS

Time Step Δa

Time Step Δa

Time Step Δa

Time Step Δc

Coupler

MOM4Time Step Δo

Time Step Δi

Time Step Δo

Time Step Δi

Time Step Δo

Time Step Δi

Block: data domainArrow line: data exchange

Coupled architecture: parallelismGFS

Coupler redistMOM4

ATM

SBL

LNDICE

OCN

Regrid

Regrid with Mask

Redistribution

Data FlowFast loop: if Δa= Δc= Δi, coupled at every time step

Slow loop: Δo

Δo

GFS CouplerSea-ice

Ocean

ATM (dummy)

ΔcΔa Δi

LAND (dummy)

Passing variables

• Atmosphere to sea-ice:• - downward short- and long-wave radiations,• - tbot, qbot, ubot, vbot, pbot, zbot,• - snowfall, psurf, coszen• Atmosphere to ocean:• - net downward short- and long-radiations,• - sensible and latent heat fluxes,• - wind stresses and precipitation• Sea-ice/ocean to atmosphere

– surface temperature,– sea-ice fraction and thickness, and snow depth

Coupler Configuration

• Fast loop: can be coupled at every time step

• Slow loop:

a. passing variables accumulated in fast loop

b. can be coupled at each ocean time step

Thank you!Thank you!