In CESM, coupler code has been improved in order to remove the need to change any coupler code when adding the exchange of new fields between model components. To accomplish this, a new standardized naming convention has been introduced for field names that are exchanged between model components. This is summarized below.
====================================================================
New standardized naming convention
====================================================================
---------
definitions:
---------
state-prefix
first 3 characters: Sx_, Sa_, Si_, Sl_, So_
one letter indices: x,a,l,i,o,s,g,r
x => coupler (mapping, merging, atm/ocn flux calc done on coupler procs)
a => atm
l => lnd
i => ice
o => ocn
g => glc
s => snow (from clm to glc)
r => rof
state-name
what follows state prefix
flux-prefix
first 5 characters: Flmn__
lm => between components l and m
n => computed by component n
example: Fioi => ice/ocn flux computed by ice
example: Fall => atm/lnd flux computed by lnd
If flux prefix has first letter of P (so first five characters are PFlmn_)
then flux is passed straight through without scaling by the corresponding fraction)
flux-name
what follows flux-prefix
---------
rules:
---------
1) states:
a) atm attributes fields that HAVE a state-prefix of Sx_ in seq_flds_x2a_states
rule: will merge all identical values of the state-names from
seq_flds_i2x_states
seq_flds_l2x_states
seq_flds_o2x_states
seq_flds_xao_states
to obtain output state-name in seq_flds_x2a_states
rule: to merge input states that originate in the
lnd (l2x_a) will be scaled by the lndfrac
ice (i2x_a) will be scaled by the icefrac
cpl (xao_a) will be scaled by the ocnfrac
ocn (o2x_a) will be scaled by the ocnfrac
example:
seq_flds_l2x_states = "Sl_t"
seq_flds_i2x_states = "Si_t"
seq_flds_o2x_states = "So_t"
seq_flds_x2a_states = "Sx_t"
attribute fields Sl_t, Si_t, So_t, in
attribute vectors l2x_a, i2x_a, o2x_a will be
merged to obtain attribute Sx_t in attribute vector x2a_a
b) atm attribute fields that DO NOT HAVE a state-prefix of Sx_ in seq_flds_x2a_states
rule: copy directly all variables that identical state-prefix
AND state-name in
seq_flds_i2x_states and seq_flds_x2a_states
seq_flds_l2x_states and seq_flds_x2a_states
seq_flds_o2x_states and seq_flds_x2a_states
seq_flds_xao_states and seq_flds_x2a_states
example
seq_flds_i2x_states = ":Si_snowh"
seq_flds_x2a_states = ":Si_snowh"
attribute field of Si_snowh in i2x_a will be copied to
attribute field Si_snowh in x2a_a
2) fluxes:
rule: will merge all identical values of the flux-names from
seq_flds_i2x_states
seq_flds_l2x_states
seq_flds_o2x_states
seq_flds_xao_states
to obtain output state-name in seq_flds_x2a_states
rule: input flux fields that originate in the
lnd (l2x_a) will be scaled by the lndfrac
ice (i2x_a) will be scaled by the icefrac
- ignore all fluxes that are ice/ocn fluxes (e.g. Fioi_)
cpl (xao_a) will be scaled by the ocnfrac
ocn (o2x_a) will be scaled by the ocnfrac+icefrac
====================================================================
New user specified fields
====================================================================
New fields that are user specidied can be added as namelist variables
by the user in the cpl namelist seq_flds_user using the namelist variable
array cplflds_customs. The user specified new fields must follow the
above naming convention.
As an example, say you want to add a new state 'foo' that is passed
from the land to the atm - you would do this as follows
apos;seq_flds_user
cplflds_custom = 'Sa_foo->a2x', 'Sa_foo->x2a'
/
This would add the field 'Sa_foo' to the character strings defining the
attribute vectors a2x and x2a. It is assumed that code would need to be
introduced in the atm and land components to deal with this new attribute
vector field.
Currently, the only way to add this is to edit $CASEROOT/user_nl_cpl
====================================================================
Coupler fields use cases
====================================================================
Previously, new fields that were needed to be passed between components
for certain compsets were specified by cpp-variables. This has been
modified to now be use cases. The use cases are specified in the
namelist cpl_flds_inparm and are currently triggered by the xml
variables CCSM_VOC, CCSM_BGC and GLC_NEC.
====================================================================
|