The Coupler

1
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
2
The Coupled model MOM4

• Parallel programming model in MOM4 SPMD

MOM4.exe
ATM LAND Sea Ice
Ocean
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GFS-MOM4 Coupler
Parallel programming model MPMD (Multiple
Program Multiple Data)
MOM4
GFS
Time Step ?o
Time Step ?a
Time Step ?i
Coupler
Time Step ?o
Time Step ?a
Time Step ?i
Time Step ?c
Time Step ?a
Time Step ?o
Time Step ?i
4
Coupled architecture parallelism
GFS
Coupler redist
MOM4
ATM
Regrid
SBL
Regrid with Mask
LND
ICE
Redistribution
OCN
5
Data Flow
Fast loop if ?a ?c ?i, coupled at every time
step Slow loop ?o
ATM (dummy)
LAND (dummy)
GFS
Coupler
Sea-ice
?c
?i
?a
Ocean
?o
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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

7
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

8
Thank you!