verification/global_with_exf/README.md

0c90ef582a Jean*0001 Global ocean on Lat-Lon grid using forcing from pkg/exf
                0002 =========================================================
f1b47febb7 Jean*0003 This experiment has been moved (PR #830, #944):
                0004 1. inside `global_oce_latlon` (Forward primary and secondary set-up)
                0005    and is now run there.
0c90ef582a Jean*0006 2. inside `global_oce_latlon` (Adjoint set-ups) and is now run there
                0007    as a secondary test ("global_oce_latlon.w_exf")
                0008    using `input_ad.w_exfs/` and `input_tap.w_exf/`.
                0009
                0010 Original Description:
                0011 =====================
                0012
57bf62b584 Dimi*0013  heimbach@mit.edu 07-Nov-2002.
c5d1c04a71 Patr*0014 This verification experiment is almost identical to the
0c90ef582a Jean*0015 `tutorial_global_oce_latlon` experiment, except that it uses
                0016 the `exf` (and `cal`) package instead of the
c5d1c04a71 Patr*0017 external_fields_load routine.
                0018 To obtain identical results between the two experiments,
                0019 the following 2 modifications are necessary:
0c90ef582a Jean*0020 1. in `external_fields_load.F`:
c5d1c04a71 Patr*0021    replace the line
0c90ef582a Jean*0022       `Imytm=int(myTime*rdt+0.5)`
c5d1c04a71 Patr*0023    by
0c90ef582a Jean*0024       `Imytm=int((myTime+1296000.)*rdt+0.5)`
                0025 2. in `exf_set_climsst.F`:
c5d1c04a71 Patr*0026    comment the 'quality' check, i.e. avoid the setting
0c90ef582a Jean*0027    to freezing temperature if less than `climtempfreeze`.
bda7c25f4a Dimi*0028
                0029 ================================
                0030
                0031 menemenlis@jpl.nasa.gov 05-Aug-2003
                0032
0c90ef582a Jean*0033 Input-field spatial interpolation has been added to `pkg/exf`.
                0034 It is enabled by defining CPP option `USE_EXF_INTERPOLATION`
                0035 in `EXF_CPPOPTIONS.h` or in `ECCO_CPPOPTIONS.h`
57bf62b584 Dimi*0036 Both bi-linear and bi-cubic interpolation schemes are supported.
bda7c25f4a Dimi*0037
57bf62b584 Dimi*0038 This package is a placeholder until a more general coupler
                0039 is made available by the ESMF project.  The output grid can be
                0040 arbitrary (cubed-sphere should be OK), but it is assumed that
                0041 the input grid is Cartesian with arbitrary latitude increments
                0042 in the y-direction and with equidistant longitude increments in
bda7c25f4a Dimi*0043 the x-direction.  The input grid must encompass the complete
                0044 output grid in the y-direction (i.e., extrapolation is not
57bf62b584 Dimi*0045 supported).  It is also assumed that the grid is periodic in
                0046 the x-direction; to use the interpolation routine with a
                0047 non-periodic domain, make sure there is sufficient padding
                0048 at the edges, i.e., two points for bicubic and one for bilinear
                0049 interpolation.
bda7c25f4a Dimi*0050
0c90ef582a Jean*0051 The `verification/global_with_exf` experiment has been modified to use
                0052 the `USE_EXF_INTERPOLATION` option, the input grids being defined by variables
                0053 `*_lon0`, `*_lon_inc`, `*_lat0`, `*_lat_inc`, `*_nlon` and `*_nlat`
                0054 in `input/dat.exf` and `input/data.exf_clim`
bda7c25f4a Dimi*0055
0c90ef582a Jean*0056 ```
bda7c25f4a Dimi*0057    *_lon0, *_lat0    :: lon and lat of sw corner of global input grid
                0058    *_lon_inc         :: scalar x-grid increment
                0059    *_lat_inc         :: vector y-grid increments
                0060    *_nlon and *_nlat :: input x-grid and y-grid size
0c90ef582a Jean*0061 ```
bda7c25f4a Dimi*0062 In this particular example the input and output grids are
57bf62b584 Dimi*0063 the same, so the results of the verification experiment remain
bda7c25f4a Dimi*0064 unchanged from before.