Input File Format
These user-provided files define the surface topography, ocean bathymetry, land/sea mask, and vegetation/landuse categories.
Topography + Bathymetry » topography.nc
The topobathy.nc netCDF file should contain topography and bathymetry on a regular latitude/longitude grid (e.g., 2°x2°). Positive values represent height above sea level and negative values represent ocean bathymetry. The topobathy.nc defines your land/ocean mask.
netCDF format
- Coordinate variables: lat(lat), lon(lon)
- longitude: 0 to 360°
- latitude: -90 to 90°
Vegetation/Landuse » vegetation.nc
The vegetation.nc netCDF file should contain land use (i.e., vegetation) on a regular latitude/longitude grid (e.g., 2°x2°).
netCDF format
- Coordinate variables: lat(lat), lon(lon)
- longitude: 0 to 360°
- latitude: -90 to 90°
CLM PLANT FUNCTION TYPE (PFT)
For most deep time paleo simulations, we assign LSM (Land Surface Model) land-use types for each grid point and then convert these LSM types to CLM (Community Land Model) surface information using the tool paleo_mkraw_cesm1.csh. Because CLM requires a complicated array of surface information for each grid cell, whereas LSM uses a simple integer value to represent land-use at each grid point, assigning an LSM integer value and using the paleo_mkraw_cesm1.csh tool to convert to LSM types to CLM format provides a simple method to create surface data information for deep time.
Modelers may first need to construct LSM land cover maps from biome maps using the LSM definitions and CLM PFT definitions used in paleo_mkraw_cesm1.csh
LSM land-use types are used in paleo_mkraw_cesm1.csh because LSM was the predecessor to CLM3 and used in CSM1.4. If this does not suite your needs, you will need to modify paleo_mkraw.csh to convert from your preferred land-use type structure to CLM surface data information.
User Namelist Changes
Recommended namelist changes to configure the CESM1.2.x model for a paleoclimate simulation.
POP2 » Near Modern (LGM example)
POP2 » Deep Time (Permian example)
- horiz_grid_file = '/mypath/ocn/mk_ocn_grid/permian/grid.pop.da'
- topography_file = '/mypath/ocn/mk_ocn_grid/permian/kmt.da'
- region_mask_file = '/mypath/ocn/region_mask/region.permian.be.ieeei4'
- region_info_file = '/mypath/ocn/region_mask/perm_gx1v6_region_ids.permian'
- diag_transport_file = '/mypath/ocn/region_mask/perm_gx1v6_transport_contents.permian'
- lat_aux_grid_type = 'user-specified'
- lat_aux_begin = -90.0
- lat_aux_end = 90.0
- n_lat_aux_grid = 180
- moc_requested = .true.
- n_heat_trans_requested = .true.
- n_salt_trans_requested = .true.
- n_transport_reg = 1
- dt_count = 23
- overflows_on = .false.
- overflows_interactive = .false.
- lhoriz_varying_bckgrnd = .false.
- ldiag_velocity = .false.
- ltidal_mixing = .false.
- bckgrnd_vdc1 = 0.524
- bckgrnd_vdc2 = 0.313
Deep Time POP2 details
!-- Specify the grid type to avoid the model assumption of a uniform grid in the southern hemisphere (i.e., gx1v6).
- lat_aux_grid_type = 'user-specified'
- lat_aux_begin = -90.0
- lat_aux_end = 90.0
- n_lat_aux_grid = 180
- moc_requested = .true.
- n_heat_trans_requested = .true.
- n_salt_trans_requested = .true.
- n_transport_reg = 1
- transport_reg2_names = 'Eq Bay','Mid-ocean Ridge'
- dt_count = 23
- overflows_on = .false.
- overflows_interactive = .false.
- init_ts_file = '/glade/p/cesm/palwg/paleo_setup/ocn/ic/ts_init_b20.681_1100-01_s_35.60level.dat'
- init_ts_option = 'mean'
- lhoriz_varying_bckgrnd = .false.
- ldiag_velocity = .false.
- ltidal_mixing = .false.
- bckgrnd_vdc1 = 0.524
- bckgrnd_vdc2 = 0.313
CAM5 » Near Modern and Deep Time
Greenhouse gases
Example 1: Fixed GHG
Example 2: Time varying GHG
Solar Forcing
Example 1: Time varying solar
Example 2: Fixed solar (year 850AD)
Example 3: Fixed solar (year 1850)
Volcanic Forcing (Default=OFF)
Example 1: Volcanoes turned ON
CLM4.0 » user_nl_clm » Near Modern
CLM4.0 » user_nl_clm » Deep Time
finidat* (See Known Problems)
RTM » user_nl_rtm » Near Modern + Deep Time
CICE » user_nl_cice » Near Modern
CICE » user_nl_cice » Deep Time
CPL » user_nl_cpl » Near Modern example for Last Glacial Maximum (-19050 = 1950-21,000)
CPL » user_nl_cpl » Deep Time
Known Problems
Solution:
- /CASEDIR/Buildconf/clm.buildnml.csh
NEW: set clm_startfile = "b.e11.B1850C5CN.f19_g16.008.clm2.r.1001-01-01-.IP.B1850C5CN.f16_g16.1yrPT.001.nc" OLD: set clm_startfile = "-clm_startfile ${RUN_REFCASE}.clm2.r.${RUN_REFDATE}-${RUN_REFTOD}.nc"