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Experiment 038: Description

GMAO CGCM Experiment 38 uses the NSIPP-1 atmospheric model, the Poseidon v4 ocean model, and the Mosaic v3 land surface model as its core. The coupled model also includes a thermodynamic sea-ice model.

The atmospheric resolution is 1.25° longitude by 1° latitude by 34 sigma layers. The ocean resolution is 0.625° longitude by 1/3° latitude by 27 layers. The models are coupled once per day.

This experiment uses a linear interpolation routine to couple the atmospheric fields to the ocean, an improved ocean mixed layer model that can use several layers to resolve the mixed layer, relaxation to Levitus 1998 surface salinity climatology with a 2-year timescale, and some minor fixes to errors with the code and boundary conditions.

Parameters used in the ocean model:

Mixed Layer parameters:

• Penetrating radiation fraction = 0.31
• Penetrating radiation depth = from SeaWifs climatology
• Friction velocity (u3) coefficient = 1.25
• Fraction of negative surface buoyancy flux used for deepening = 1.0
• Mixed layer calculation = 1/day

Shapiro Filter parameters for temperature (T) and momentum (u); there is no mass filtering:

• u_filter_interval = 1 day
• u_filter_order = 8
• u_filter_timescale = 1 day
• t_filter_interval = 1 day
• t_filter_order = 4
• t_filter_timescale = 2 days

Vertical Diffusion parameters (kPP-type mixing scheme):

• Vertical mixing interval = 12 hours
• Kappa_T_min = 1.0E-05
• Kappa_T_max = 0.005
• Kappa_T_crit = 0.25
• Kappa_T_convect = 1.E06
• Kappa_T_0 = 5.E-03
• Kappa_S_min = 1.0E-05
• Kappa_S_max = 0.005
• Kappa_S_crit = 0.25
• Kappa_S_convect = 1.E06
• Nu_max = 0.005
• Nu_crit = 0.25
• Nu_min = 1.E-04
• Nu_convect = 100.
• Nu_0 = 0.005