Each component model exchanges data with the Coupler only. Component models have no direct connection with each other -- all data is routed through the Coupler. Most data is in the form of 2D fields. This data is accompanied by certain timing and control information (arrays of scalar real or integer values), such as the current simulation data and time.
All data exchanged conforms to this units convention:
o Sign convention:
positive value <=> downward flux
o Unit convention:
temperature ~ Kelvin
salt ~ g/kg
velocity ~ m/s
pressure ~ N/m^2 = Pa
humidity ~ kg/kg
air density ~ kg/m^3
momentum flux ~ N/m^2
heat flux ~ W/m^2
water flux ~ (kg/s)/m^2
salt flux ~ (kg/s)/m^2
coordinates ~ degrees north or east
area ~ radians^2
domain mask ~ 0 <=> an inactive grid cell
This section provides a list of the time invariant data exchanged between the
Coupler and each component model. Generally this data is the "domain" data:
coordinate arrays, domain mask, cell areas, etc. It is assumed that the
domain of all models is represented by a 2D array (although not necessarily a
latitude/longitude grid).
Data sent to Coupler
domain data
* grid cell's center coordinates, zonal (degrees north)
* grid cell's center coordinates, meridional (degrees east)
* grid cell's four vertex coordinates, zonal (degrees north)
* grid cell's four vertex coordinates, meridional (degrees east)
* grid cell area (radians squared)
* grid cell domain mask ( 0 <=> not in active domain)
* ni,nj: the dimensions of the underlying 2D array data structure
time coordination data
* ncpl: number of times per day the component will communicate (exchange
data) with the Coupler.
other information
* IC flag: indicates whether the Coupler should use model IC's contained
on the Coupler's restart file or IC's in the initial message sent from
the component model.
Data sent to Component Models
time coordination data
* date, seconds: the exact time the Coupler will start the simulation from.
This section provides a list of the time-evolving data sent exchanged between the Coupler and each component model. Generally this is state, flux, and diagnostic quantities. Each component model provides the Coupler with a set of output fields. Output fields from a model include output states (which can be used by another component to compute fluxes) and output fluxes (fluxes that were computed within the model and which need to be exchanged with another component model. The Coupler provides each component model with input fields. Input fields sent to a model include input states (the state variables of other models, which are needed to do a flux calculation) and input fluxes (a forcing fields computed by some other component). Flux fields sent to or from the Coupler are understood to apply over the communication interval beginning when the data was received and ending when the next message is received. The component models must insure that fluxes sent to the Coupler are computed with this in mind -- failure to do so may result in the non-conservation of fluxes. For example, if the atmosphere component communicates with the Coupler once per hour, but takes three internal time steps per hour, then the precipitation (water flux) sent to the Coupler should be the average precipitation over an hour (the average precipitation over three internal time steps). Similarly, if the ocean component has a communication interval of one day, but takes 50 internal time steps per day, then the precipitation flux field it receives from the Coupler should be applied as ocean boundary condition forcing for all 50 time steps during the next communication interval.
Data sent to Coupler
states
* layer height (m)
* zonal velocity (m/s)
* meridional velocity (m/s)
* temperature (Kelvin)
* potential temperature (Kelvin)
* pressure (Pa)
* equivalent sea level pressure (Pa)
* specific humidity (kg/kg)
* density humidity (kg/m^3)
fluxes
* precipitation: liquid, convective ((kg/s)/m^2)
* precipitation: liquid, large-scale ((kg/s)/m^2)
* precipitation: frozen, convective ((kg/s)/m^2)
* precipitation: frozen, large-scale ((kg/s)/m^2)
* longwave radiation, downward (W/m^2)
* shortwave radiation: downward, visible , direct (W/m^2)
* shortwave radiation: downward, near-infrared, direct (W/m^2)
* shortwave radiation: downward, visible , diffuse (W/m^2)
* shortwave radiation: downward, near-infrared, diffuse (W/m^2)
diagnostic quantities
* net shortwave radiation (W/m^2)
Data received from Coupler
states
* albedo: visible , direct
* albedo: near-infrared, direct
* albedo: visible , diffuse
* albedo: near-infrared, diffuse
* surface temperature (Kelvin)
* snow height (m)
* ice fraction
* ocean fraction
* land fraction (implied by ice and ocean fractions)
fluxes
* zonal surface stress (N/m^2)
* meridional surface stress (N/m^2)
* latent heat (W/m^2)
* sensible heat (W/m^2)
* longwave radiation, upward (W/m^2)
* evaporation ((kg/s)/m^2)
diagnostic quantities
* 2 meter reference air temperature (Kelvin)
Data sent to Coupler
states
* ice fraction
* surface temperature (Kelvin)
* albedo: visible , direct
* albedo: near-infrared, direct
* albedo: visible , diffuse
* albedo: near-infrared, diffuse
fluxes
* atm/ice: zonal surface stress (N/m^2)
* atm/ice: meridional surface stress (N/m^2)
* atm/ice: latent heat (W/m^2)
* atm/ice: sensible heat (W/m^2)
* atm/ice: longwave radiation, upward (W/m^2)
* atm/ice: evaporation ((kg/s)/m^2)
* ice/ocn: penetrating shortwave radiation (W/m^2)
* ice/ocn: ocean heat used for melting (W/m^2)
* ice/ocn: melt water ((kg/s)/m^2)
* ice/ocn: salt flux ((kg/s)/m^2)
* ice/ocn: zonal surface stress (N/m^2)
* ice/ocn: meridional surface stress (N/m^2)
diagnostic quantities
* net shortwave radiation (W/m^2)
* 2 meter reference air temperature (Kelvin)
Data received from Coupler
states
* ocn: temperature (Kelvin)
* ocn: salinity (g/kg)
* ocn: zonal velocity (m/s)
* ocn: meridional velocity (m/s)
* atm: layer height (m)
* atm: zonal velocity (m/s)
* atm: meridional velocity (m/s)
* atm: potential temperature (Kelvin)
* atm: temperature (Kelvin)
* atm: specific humidity (kg/kg)
* atm: density (kg/m^3)
fluxes
* ocn: dh/dx: zonal surface slope (m/m)
* ocn: dh/dy: meridional surface slope (m/m)
* ocn: Q>0: heat of fusion (W/m^2), or
Q<0: melting potential (W/m^2)
* atm: shortwave radiation: downward, visible , direct (W/m^2)
* atm: shortwave radiation: downward, near-infrared, direct (W/m^2)
* atm: shortwave radiation: downward, visible , diffuse (W/m^2)
* atm: shortwave radiation: downward, near-infrared, diffuse (W/m^2)
* atm: longwave radiation, downward (W/m^2)
* atm: precipitation: liquid ((kg/s)/m^2)
* atm: precipitation: frozen ((kg/s)/m^2)
Data sent to Coupler
states
* surface temperature (Kelvin)
* albedo: visible , direct
* albedo: near-infrared, direct
* albedo: visible , diffuse
* albedo: near-infrared, diffuse
* snow depth (m)
fluxes
* zonal surface stress (N/m^2)
* meridional surface stress (N/m^2)
* latent heat (W/m^2)
* sensible heat (W/m^2)
* longwave radiation, upward (W/m^2)
* evaporation ((kg/s)/m^2)
* coastal runoff ((kg/s)/m^2)
diagnostic quantities
* 2 meter reference air temperature (Kelvin)
Data received from Coupler
states
* atm layer height (m)
* atm zonal velocity (m/s)
* atm meridional velocity (m/s)
* atm potential temperature (Kelvin)
* atm specific humidity (kg/kg)
* atm pressure (Pa)
* atm temperature (Kelvin)
fluxes
* precipitation: liquid, convective ((kg/s)/m^2)
* precipitation: liquid, large-scale ((kg/s)/m^2)
* precipitation: frozen, convective ((kg/s)/m^2)
* precipitation: frozen, large-scale ((kg/s)/m^2)
* longwave radiation, downward (W/m^2)
* shortwave radiation: downward, visible , direct (W/m^2)
* shortwave radiation: downward, near-infrared, direct (W/m^2)
* shortwave radiation: downward, visible , diffuse (W/m^2)
* shortwave radiation: downward, near-infrared, diffuse (W/m^2)
Data sent to Coupler
states
* surface temperature (Kelvin)
* salinity (g/kg)
* zonal velocity (m/s)
* meridional velocity (m/s)
fluxes
* dh/dx: zonal surface slope (m/m)
* dh/dy: meridional surface slope (m/m)
* Q>0: heat of fusion (W/m^2), or
Q<0: melting potential (W/m^2)
Data received From Coupler
states
* equivalent sea level pressure (Pa)
* ice fraction
fluxes
* zonal surface stress (N/m^2)
* meridional surface stress (N/m^2)
* shortwave radiation, net (W/m^2)
* latent heat (W/m^2) (note: derived from evaporation)
* sensible heat (W/m^2)
* longwave radiation, upward (W/m^2)
* longwave radiation, downward (W/m^2)
* ocean heat used for melting (W/m^2)
* salt flux ((kg/s)/m^2)
* precipitation: rain + snow ((kg/s)/m^2)
* evaporation ((kg/s)/m^2)
* melt water ((kg/s)/m^2)
* coastal runoff ((kg/s)/m^2)