The Coupler Jun Wang Xingren Wu Jinde Wang

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: MOM 4 • Parallel programming model in MOM 4: SPMD MOM 4. exe ATM+ LAND+ Sea Ice Ocean

GFS-MOM 4 Coupler Parallel programming model: MPMD (Multiple Program Multiple Data) MOM 4 GFS Time Step Δo Time Step Δa Time Step Δi Coupler Time Step Δo Time Step Δc Time Step Δi Time Step Δa Time Step Δo Time Step Δi Block: data domain Arrow line: data exchange

Coupled architecture: parallelism GFS MOM 4 Coupler redist ATM Regrid SBL Regrid with Mask LND Redistribution ICE OCN

Data Flow Fast loop: if Δa= Δc= Δi, coupled at every time step Slow loop: Δo ATM (dummy) GFS Coupler Δa Δc LAND (dummy) Sea-ice Ocean Δi Δo

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!