Tools for Displaced-Pole
Ocean Grid Generation for
CCSM2
Steve Yeager
Esther Brady
Davis
Rick Smith
John
What needs to be modified?
1. OCN
horiz_grid :
ieee r8, {ulat,ulng,htn,hte,hus,huw,utan}
topography : ieee i4, {kmt}
region_mask : ieee i4 {regionmask}
other input_template files…
2. CPL
map_ATM_to_OCN_aave.nc
map_ATM_to_OCN_bilin.nc
map_OCN_to_ATM_aave.nc
map_RUNOFF_to_OCN.nc
Tools
ns_dipole.F
generates a dipole mesh grid, (R Smith et al)
topography.F
Generates a kmt based on etopo5 data, (R Smith et al)
paleotopo.F90
Generates a kmt based on paleo data
display_hgrid_land.F
Grid display with land mask, (R Smith et al)
eCubed (C++ package)
Interactive grid display & kmt edit, (J Davis et al)
grid_bin2nc.F90
Creates a netcdf file of grid info
gridkmt_nc2bin.F90
Writes kmt in netcdf back into binary
ncview (C++ package)
All-purpose netcdf viewer (D Pierce)
(http://meteora.ucsd.edu/~pierce/ncview_home_page.html)
SCRIP (F90 package)
Remapping between grids (P Jones)
(http://climate.acl.lanl.gov/software/SCRIP/scrip_frames.htm)
(http://www.cgd.ucar.edu/csm/models/ocn-pop/scrip.shtml)
mk_grid.csh
Automates grid generation procedure, including grid & kmt
mk_ocninput.csh
Automates ocn input file modification, including region mask
mk_remap.csh
Automates atmosphereocean map generation
mk_runoff_remap.csh
Automates runoffocean map generation
map_runoff (F90 package)
Correction routines for runoffocean map
1. a. Generating a Grid
• ns_dipole* generates a
dipole mesh grid with userspecified north/south pole
locations.
• Equator is always a grid line
• Enhanced meridional
resolution at the equator
• Code tries to make aspect
ratio  1
• Nx is independent variable
(sets the order of the
resolution); Ny requires
iteration
Created using display_hgrid*
(R Smith et al)
1. b. Generating a kmt
• topography* assigns topography/kmt to
a grid based on the 1/12 degree etopo5
dataset.
• paleotopo* assigns topography/kmt to
a grid based on a paleo bathymetry
dataset in netcdf format.
Created using display_hgrid_land*
Iterate grid/kmt generation until
… for a given Nx and equatorial gaussian function, Ny is
sufficient to extend the grid into the polar continents without
wasting resolution,
… grid has acceptable min/max cell sides & aspect ratios for
active ocean points (when compared to standard grids)
1. c. Hand Edit Kmt
• eCubed* enables interactive gridviewing/kmt-editing using a
mouse & keyboard
• Reads/writes a grid netcdf file
created with grid_bin2nc*
• Convert kmt back into POP input
binary with gridkmt_nc2bin*
Created using display_hgrid_land*
Created using eCubed*
2. a. Maps between ATM & OCN
• mk_remap.csh creates atmosphereocean mappings using
SCRIP (Spherical Coordinate Remapping and Interpolation
Package) developed by Phil Jones.
2. b. Mapping Runoff to OCN
•
•
•
mk_runoff_remap.csh calls SCRIP; generates a
conservative runoffocean mapping netcdf.
BUT, it does not guarantee global water conservation
ALSO, it may require additional smoothing to prevent
excessively low ocean salinities in high runoff
regions.
•
Use map_runoff/*.F90 for
–
–
–
–
runoff map conservation correction
map matrix testing
ocean smoothing map generation & testing
map matrix multiplication.
Why are conservation corrections needed?
Potential flux loss
…where an active source
grid cell does not overlap
any (a) or only partially
overlaps (b) a destination
cell.
…where an active source
grid cell maps into an
inactive destination cell (c)
runoff_conserve_mod.F90
applies corrections
Runoff Smoothing
• runoff_smooth_mod.F90
contains routines for
generating an ocean-to-ocean
smoothing map
• Input parameters maxradius
(km) & efold (km)
• test_smooth generates netcdf
output of smoothing effects for
select source points
efold = 100km, maxradius = 500km
Runoff-to-Ocean Map with Smoothing
• runoff_map_mod.F90 contains routines for matrix multiplication &
testing:
runoff grid
ocean grid
runoff grid
Smoothing Map
Corrected SCRIP Map
=
Final Map
efold = 100km,
maxradius = 500km
efold = 2000km,
maxradius = 500km
Surface Salinity Effect of Smoothing Runoff