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 
   &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.
Modify user_nl_cpl to edit this.

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. This use cases are specified in the 
namelist cpl_flds_inparm and are currently triggered by the xml variable CCSM_BGC.
If CCSM_BGC is set to 'CO2_DMSA', then flds_co2_dmsa will be set to .true.

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. This use cases are specified in the 
namelist cpl_flds_inparm and are currently triggered by the xml variable CCSM_BGC.
If CCSM_BGC is set to 'CO2A', then flds_co2a will be set to .true.

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. This use cases are specified in the 
namelist cpl_flds_inparm and are currently triggered by the xml variable CCSM_BGC.
If CCSM_BGC is set to 'CO2B', then flds_co2b will be set to .true.

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. This use cases are specified in the 
namelist cpl_flds_inparm and are currently triggered by the xml variable CCSM_BGC.
If CCSM_BGC is set to 'CO2C', then flds_co2c will be set to .true.

Number of cism elevation classes. 
Set by the xml variable GLC_NEC in env_run.xml

turns on bfb option in coupler which produce bfb results in the
coupler on different processor counts.  

default: .false.

Allow same branch casename as reference casename

  
sets the diagnotics level of the monthy budgets. [0,1,2,3], 
written only if do_budgets variable is .true.,
0=none,
1=+net summary budgets, 
2=+detailed lnd/ocn/ice component budgets,
3=+detailed atm budgets

default: 1

case description.  
set by CASESTR in env_run.xml.

case name.  
set by CASE in env_case.xml.

default: true

  
cpl decomp option (0=default, 1=comp decomp, 2=rearr comp decomp, 3=new single 1d seg

default: 0

hostname information, 
set by MACH in env_case.xml

Level of debug output, 0=minimum, 1=normal, 2=more, 3=too much
set by INFO_DBUG in env_run.xml 

default: 1

model version documentation, 
set by CCSM_REPOTAG in env_run.xml

turns on ocean tight coupling flag which forces the ocean to coupling
at the same time as the other surface models.  by default, there is a
lag of one coupler timestep in addition to any difference in coupling
frequency to accomodate the ability to run the ocean concurrently with
the rest of the system for performance reasons.  

default: .false.

Driver restart filename.
(NOTE: Normally THIS IS NOT USED -- Set with RUN_REFCASE and RUN_REFDATE)

mode to start the run up, [startup,branch,continue], 
automatically derived from RUN_TYPE in env_run.xml

location of timing checkpoint output.

location of timing output.

username documentation
set by CCSMUSER in env_run.xml

Only used for C,G compsets: if true, compute albedos to work with daily avg SW down

default: false

Only used for C,G compsets: if ocn, ocn provides EP balance factor for precip

default: off

Error tolerance for differences in atm/land areas in domain checking

default: 1.0e-07

Error tolerance for differences in atm/land lat/lon in domain checking

default: 1.0e-12

Error tolerance for differences in atm/land masks in domain checking

default: 1.0e-13

Error tolerance for differences in fractions in domain checking

default: 1.0e-02

Error tolerance for differences in ocean/ice lon/lat in domain checking

default: 1.0e-1

Error tolerance for differences in ocean/ice lon/lat in domain checking

default: 1.0e-2

Error tolerance for differences in ocean/ice masks in domain checking

default: 1.0e-06

  
Grid for atm ocn flux calc (untested)

default: ocn

atm to ice flux mapping file for fluxes (currently first order conservative)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to ice state mapping file for states (currently bilinear)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to ice state mapping file for velocity (currently bilinear or patch)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to land mapping file for fluxes

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to land mapping file for states

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to ocn flux mapping file for fluxes (currently first order conservative)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to ocn state mapping file for states (currently bilinear)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

atm to ocn state mapping file for velocity (currently bilinear or patch)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

ice to atm mapping file for fluxes (currently first order conservative)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

ice to atm mapping file for states

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

land to atm mapping file for fluxes

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

land to atm mapping file for states

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

lnd to runoff conservative mapping file

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

ocn to atm mapping file for fluxes (currently first order conservative)

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

ocn to atm mapping file for states

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

runoff to lnd conservative mapping file

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

runoff to ocn conservative mapping file

The type of mapping desired, either "source" or "destination" mapping.
X is associated with rearrangement of the source grid to the
destination grid and then local mapping.  Y is associated with mapping
on the source grid and then rearrangement and sum to the destination
grid.

tells the coupler to treat the atm and land grids as "the same".  
automatically set by comparison of ATM_GRID and LND_GRID which are set in env_case.xml.  

default: true

tells the coupler to treat the atm and ocean grids as "the same".  
automatically set by comparison of ATM_GRID and OCN_GRID which are set in env_case.xml.  

default: true

tells the coupler to treat the runoff and ocean grids as "the same".  
automatically set by comparison of LND_GRID and OCN_GRID which are set in env_case.xml.  

default: false

invoke pole averaging corrections in shr_map_mod weights generation

default: true

vect_map
turns on the vector mapping option for u and v vector mapping between
atm and ocean grids in the coupler.  the options are none, npfix,
cart3d, cart3d_diag, cart3d_uvw, and cart3d_uvw_diag.  the none option
results in scalar mapping independently for the u and v field which
tends to generate large errors near the poles.  npfix is the
traditional option where the vectors are corrected on the ocean grid
north of the last latitude line of the atmosphere grid.  the cart3d
options convert the east (u) and north (v) vectors to 3d (x,y,z)
triplets, and maps those fields before converting back to the east (u)
and north (v) directions.  the cart3d ignores the resuling "w"
velocity.  the cart3d_uvw calculates the resulting u and v vectors by
preserving the total "u,v,w" speed and the angle of the (u,v) vector.
the _diag options just add diagnotics to the log file about the vector
mapping.  

default: npfix

  
sets the diagnotics level of the annual budgets. [0,1,2,3], 
written only if do_budgets variable is .true.,
0=none,
1=+net summary budgets, 
2=+detailed lnd/ocn/ice component budgets,
3=+detailed atm budgets

default: 1

  
sets the diagnotics level of the daily budgets. [0,1,2,3], 
written only if do_budgets variable is .true.,
0=none,
1=+net summary budgets, 
2=+detailed lnd/ocn/ice component budgets,
3=+detailed atm budgets

default: 0

  
sets the diagnotics level of the instantaneous budgets. [0,1,2,3],
written only if BUDGETS variable is true
0=none, 
1=+net summary budgets, 
2=+detailed lnd/ocn/ice component budgets, 
3=+detailed atm budgets

default: 0

  
sets the diagnotics level of the longterm budgets written at the end
of the year. [0,1,2,3], 
written only if do_budgets variable is .true.,
0=none, 
1=+net summary budgets, 
2=+detailed lnd/ocn/ice component budgets, 
3=+detailed atm budgets, 

default: 1

  
sets the diagnotics level of the longterm budgets written at the end
of each run. [0,1,2,3], 
written only if do_budgets variable is .true.,
0=none, 
1=+net summary budgets, 
2=+detailed lnd/ocn/ice component budgets, 
3=+detailed atm budgets, 

default: 0

logical that turns on diagnostic budgets, false means budgets will never be written

default: false

logical to write an extra initial coupler history file

turns on coupler history stream for instantaneous atm to coupler fields.  

default: false

turns on coupler history stream for daily average atm to coupler fields.  

default: false

turns on coupler history stream for 3-hour average atm to coupler fields.  

default: false

turns on coupler history stream for 3-hour average atm to coupler precip fields.  

default: false

turns on coupler history stream for instantaneous land to coupler fields.  

default: false

turns on coupler history stream for instantaneous runoff to coupler fields.  

default: false

turns on coupler history stream for annual sno to coupler fields.  

default: false

eccentricity of orbit, used when orb_mode is fixed_parameters.  

default: SHR_ORB_UNDEF_REAL (1.e36)
(Not currently used in build-namelist)

year of orbit, used when orb_mode is fixed_year or variable_year.

default: 1990

model year associated with orb_iyear when orb_mode is variable_year.  

default: 1990

  
orbital model setting.  this sets how the orbital mode will be
configured.  
"fixed_year" uses the orb_iyear and other orb inputs are ignored.  In
this mode, the orbital parameters are constant and based on the year.
"variable_year" uses the orb_iyear and orb_iyear_align.  In this mode,
the orbital parameters vary as the model year advances and the model
year orb_iyear_align has the equivalent orbital year of orb_iyear.
"fixed_parameters" uses the orb_eccen, orb_mvelp, and orb_obliq to set
the orbital parameters which then remain constant through the model
integration.  set by ORBITAL_MODE in env_run.xml.  [fixed_year,
variable_year, fixed_parameters]

default: 'fixed_year'.

obliquity of orbit in degrees, used when orb_mode is fixed_parameters.  

default: SHR_ORB_UNDEF_REAL (1.e36)
(Not currently used in build-namelist)

location of vernal equinox in longitude degrees, used when orb_mode is fixed_parameters.

default: SHR_ORB_UNDEF_REAL (1.e36)
(Not currently used in build-namelist)

atm coupling interval in seconds
set via ATM_NCPL in env_run.xml.  
ATM_NCPL is the number of times the atm is coupled per NCPL_BASE_PERIOD
NCPL_BASE_PERIOD is also set in env_run.xml and is the base period
associated with NCPL coupling frequency, nad has valid values: hour,day,year,decade

default: 0

atm coupling interval offset in seconds

default: 0

calendar in use.  [NO_LEAP, GREOGORIAN].  
set by CALENDAR in env_run.xml

default: "NO_LEAP".  

true => write restarts at end of run
forces a restart write at the end of the run in addition to any
setting associated with rest_option.  default=true.  this setting
will be set to false if restart_option is none or never.

default: false

glc coupling interval in seconds
set via GLC_NCPL in env_run.xml.  
GLC_NCPL is the number of times the glc is coupled per NCPL_BASE_PERIOD
NCPL_BASE_PERIOD is also set in env_run.xml and is the base period
associated with NCPL coupling frequency, nad has valid values: hour,day,year,decade

default: 0

glc coupling interval offset in seconds

default: 0

Sets coupler time-average history file frequency (like restart_option)

sets the run length with histavg_n and histavg_ymd
histavg_option alarms are:
[none/never], turns option off
[nstep/s]   , history every histavg_n nsteps  , relative to current run start time
[nsecond/s] , history every histavg_n nseconds, relative to current run start time
[nminute/s] , history every histavg_n nminutes, relative to current run start time
[nhour/s]   , history every histavg_n nhours  , relative to current run start time
[nday/s]    , history every histavg_n ndays   , relative to current run start time
[monthly/s] , history every           month   , relative to current run start time
[nmonth/s]  , history every histavg_n nmonths , relative to current run start time
[nyear/s]   , history every histavg_n nyears  , relative to current run start time
[date]      , history at histavg_ymd value
[ifdays0]   , history at histavg_n calendar day value and seconds equal 0
[end]       , history at end

yyyymmdd format, sets coupler time-average history date (like restart_ymd)

sets coupler snapshot history file frequency (like restart_n)
set by HIST_N in env_run.xml.

coupler history snapshot option (used with history_n and history_ymd)
set by HIST_OPTION in env_run.xml.
history_option alarms are:
[none/never], turns option off
[nstep/s]   , history snapshot every history_n nsteps  , relative to current run start time
[nsecond/s] , history snapshot every history_n nseconds, relative to current run start time
[nminute/s] , history snapshot every history_n nminutes, relative to current run start time
[nhour/s]   , history snapshot every history_n nhours  , relative to current run start time
[nday/s]    , history snapshot every history_n ndays   , relative to current run start time
[monthly/s] , history snapshot every           month   , relative to current run start time
[nmonth/s]  , history snapshot every history_n nmonths , relative to current run start time
[nyear/s]   , history snapshot every history_n nyears  , relative to current run start time
[date]      , history snapshot at history_ymd value
[ifdays0]   , history snapshot at history_n calendar day value and seconds equal 0
[end]       , history snapshot at end

date associated with history_option date.  yyyymmdd format.  
set by HIST_DATE in env_run.xml.

ice coupling interval in seconds
set via ICE_NCPL in env_run.xml.  
ICE_NCPL is the number of times the ice is coupled per NCPL_BASE_PERIOD
NCPL_BASE_PERIOD is also set in env_run.xml and is the base period
associated with NCPL coupling frequency, nad has valid values: hour,day,year,decade

default: 0

ice coupling interval offset in seconds

default: 0

lnd coupling interval in seconds
set via LND_NCPL in env_run.xml.  
LND_NCPL is the number of times the lnd is coupled per NCPL_BASE_PERIOD
NCPL_BASE_PERIOD is also set in env_run.xml and is the base period
associated with NCPL coupling frequency, nad has valid values: hour,day,year,decade

default: 0

lnd coupling interval offset in seconds

default: 0

ocn coupling interval in seconds
set via OCN_NCPL in env_run.xml.  
OCN_NCPL is the number of times the ocn is coupled per NCPL_BASE_PERIOD
NCPL_BASE_PERIOD is also set in env_run.xml and is the base period
associated with NCPL coupling frequency, nad has valid values: hour,day,year,decade

default: 0

ocn coupling interval offset in seconds

default: 0

Ssets model restart writes with restart_option and restart_ymd (same options as stop_n)

sets the run length with stop_n and stop_ymd
stop_option alarms are:
[none/never], turns option off
[nstep/s]   , restarts every restart_n nsteps  , relative to current run start time
[nsecond/s] , restarts every restart_n nseconds, relative to current run start time
[nminute/s] , restarts every restart_n nminutes, relative to current run start time
[nhour/s]   , restarts every restart_n nhours  , relative to current run start time
[nday/s]    , restarts every restart_n ndays   , relative to current run start time
[monthly/s] , restarts every           month   , relative to current run start time
[nmonth/s]  , restarts every restart_n nmonths , relative to current run start time
[nyear/s]   , restarts every restart_n nyears  , relative to current run start time
[date]      , restarts at restart_ymd value
[ifdays0]   , restarts at restart_n calendar day value and seconds equal 0
[end]       , restarts at end

Date in yyyymmdd format, sets model restart write date with rest_option and restart_n

default: STOP_N

river runoff coupling interval in seconds
currently set by default to 10800 seconds.

default: 10800

Start time-of-day in universal time (seconds), should be between zero and 86400

default: 0

Run start date in yyyymmdd format, only used for startup and hybrid runs.

default: 00010101

Sets the run length with stop_option and stop_ymd

sets the run length with stop_n and stop_ymd
stop_option alarms are:
[none/never], turns option off
[nstep/s]   , stops every stop_n nsteps  , relative to current run start time
[nsecond/s] , stops every stop_n nseconds, relative to current run start time
[nminute/s] , stops every stop_n nminutes, relative to current run start time
[nhour/s]   , stops every stop_n nhours  , relative to current run start time
[nday/s]    , stops every stop_n ndays   , relative to current run start time
[nmonth/s]  , stops every stop_n nmonths , relative to current run start time
[monthly/s] , stops every        month   , relative to current run start time
[nyear/s]   , stops every stop_n nyears  , relative to current run start time
[date]      , stops at stop_ymd value
[ifdays0]   , stops at stop_n calendar day value and seconds equal 0
[end]       , stops at end

date in yyyymmdd format, sets the run length with stop_option and stop_n,
can be in addition to stop_option and stop_n, negative value implies off

Sets timing output file frequency (like restart_n)

Sets timing output file frequency (like rest_option but relative to run start date)
tprof_option alarms are:
[none/never], turns option off
[nstep/s]   , every tprof_n nsteps  , relative to current run start time
[nsecond/s] , every tprof_n nseconds, relative to current run start time
[nminute/s] , every tprof_n nminutes, relative to current run start time
[nhour/s]   , every tprof_n nhours  , relative to current run start time
[nday/s]    , every tprof_n ndays   , relative to current run start time
[monthly/s] , every         month   , relative to current run start time
[nmonth/s]  , every tprof_n nmonths , relative to current run start time
[nyear/s]   , every tprof_n nyears  , relative to current run start time
[date]      , at tprof_ymd value
[ifdays0]   , at tprof_n calendar day value and seconds equal 0
[end]       , at end

  
Layout of multi-instance atms (if there are more than 1)

the number of mpi tasks assigned to the atm components. 
set by NTASKS_ATM in env_configure.xml.  

the number of threads per mpi task for the atm component.  
set by NTHRDS_ATM in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the atm component.  
set by PSTRID_ATM in env_configure.xml.  

the global mpi task rank of the root processor assigned to the atm component.  
set by ROOTPE_ATM in env_configure.xml.

the number of mpi tasks assigned to the cpl components. 
set by NTASKS_CPL in env_configure.xml.  

the number of threads per mpi task for the cpl component.  
set by NTHRDS_CPL in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the cpl component.  
set by PSTRID_CPL in env_configure.xml.  

the global mpi task rank of the root processor assigned to the cpl component.  
set by ROOTPE_CPL in env_configure.xml.

  
Layout of multi-instance glcs (if there are more than 1)

the number of mpi tasks assigned to the glc components. 
set by NTASKS_GLC in env_configure.xml.  

the number of threads per mpi task for the glc component.  
set by NTHRDS_GLC in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the glc component.  
set by PSTRID_GLC in env_configure.xml.  

the global mpi task rank of the root processor assigned to the glc component.  
set by ROOTPE_GLC in env_configure.xml.

  
Layout of multi-instance ices (if there are more than 1)

the number of mpi tasks assigned to the ice components. 
set by NTASKS_ICE in env_configure.xml.  

the number of threads per mpi task for the ice component.  
set by NTHRDS_ICE in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the ice component.  
set by PSTRID_ICE in env_configure.xml.  

the global mpi task rank of the root processor assigned to the ice component.  
set by ROOTPE_ICE in env_configure.xml.

  
Layout of multi-instance lnds (if there are more than 1)

the number of mpi tasks assigned to the lnd components. 
set by NTASKS_LND in env_configure.xml.  

the number of threads per mpi task for the lnd component.  
set by NTHRDS_LND in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the lnd component.  
set by PSTRID_LND in env_configure.xml.  

the global mpi task rank of the root processor assigned to the lnd component.  
set by ROOTPE_LND in env_configure.xml.

  
Layout of multi-instance ocns (if there are more than 1)

the number of mpi tasks assigned to the ocn components. 
set by NTASKS_OCN in env_configure.xml.  

the number of threads per mpi task for the ocn component.  
set by NTHRDS_OCN in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the ocn component.  
set by PSTRID_OCN in env_configure.xml.  
default: 1

the global mpi task rank of the root processor assigned to the ocn component.  
set by ROOTPE_OCN in env_configure.xml.

  
Layout of multi-instance lnds (if there are more than 1)

the number of mpi tasks assigned to the lnd components. 
set by NTASKS_LND in env_configure.xml.  

the number of threads per mpi task for the lnd component.  
set by NTHRDS_LND in env_configure.xml.  

the mpi global processors stride associated with the mpi tasks for the lnd component.  
set by PSTRID_LND in env_configure.xml.  

the global mpi task rank of the root processor assigned to the lnd component.  
set by ROOTPE_LND in env_configure.xml.

turn on run time control of threading per pe per component by the driver

default: false

default: 0

default: .false.

future asynchronous IO capability (not currently supported). 

default: .false.

pio blocksize

pio buffer size limit

pio debug level
valid values: 0,1,2,3,4,5,6

number of io tasks in pio used generically, component based value takes precedent. 

io task root in pio used generically, component based value takes precedent. 

stride of tasks in pio used generically, component based value takes precedent. 

io type in pio used generically, component based value takes precedent.  
valid values: netcdf, pnetcdf, netcdf4p, netcdf4c, default