The FVcubed dynamical core from GFDL has a complicated and
poorly engineered interface. There is an fv_init (w/o arguments)
method to initialize it and a fv_dynamics (with a long argument
list) to execute one time step, but in addition, numerous
configuration parameters can be set. Most of these
reside in fv_control_mod (file: model/fv_control.F90).
For the most part, non-default values are not documented.
IMPORTANT: to avoid possible name conflicts, the CAM build-namelist
equivalents of these parameters always begins with the prefix
fvc_. See examples below.
The following parameters need to be set:
parameter |
definition |
Comments |
npx |
Domain size in first dimension |
No default |
npy |
Domain size in first dimension |
No default |
npz |
Number of vertical levels |
No default |
(the CAM equivalents are fvc_npx, fvc_npy and fvc_npz).
The following have sensible defaults (in the CAM implementation),
but the user will often want to change them:
parameter |
definition |
default |
npes_x |
Number of PEs for 1st (X) dimension |
1 |
npes_y |
Number of PEs for 2nd (Y) dimension |
1 |
(the CAM equivalents are fvc_npes_x and fvc_npes_y).
The following parameters have sensible default values. The user should
not change them unless s/he has extensive experience running the
dynamical core.
parameter |
definition |
default |
Comments |
hord_mt |
horiz. momentum mapping option |
9 |
for Gnomonic grids |
kord_mt |
vert. momentum mapping option |
8 |
|
hord_vt |
horiz. momentum mapping option |
9 |
10 not recommended |
hord_tm |
horiz. virt. pot. temp. option |
9 |
|
hord_dp |
horiz. delta pressure option |
9 |
delp positive definite |
hord_ze |
horiz. edge height option |
9 |
can be negative near surface |
kord_tm |
vert. virt. pot. temp. option |
-8 |
minus sign means ... |
hord_tr |
horiz. tracer transport option |
12 |
11: PPM mono constraint (Lin 2004); fast |
|
|
|
12: Huynh 2nd constraint (Lin 2004) |
|
|
|
positive definite (Lin & Rood 1996); slower |
|
|
|
>12: positive definite only (Lin & Rood 1996); fastest |
kord_tr |
vert. tracer transport option |
8 |
|
nord |
divergence damping option |
3 |
0: del-2, 1: del-4, 2: del-6, 3: del-8 |
dddmp |
coeff for del-2 div. damping |
0.0 |
for C90 or lower: 0.2 |
d2_bg |
background del-2 div. damping coeff. |
0.0 |
|
d4_bg |
background del-4 div. damping coeff. |
0.16 |
for stability, d4_bg must be <=0.16 if nord=3 |
vtdm4 |
coefficient for del-4 vorticity damping |
0.0 |
|
beta1 |
PG off-centering |
0.0 |
|
beta |
.... |
0.25 |
|
ntiles |
No. tiles that make up grid |
6 |
cubed sphere faces |
n_sponge |
No. of sponge layers at top of the atmos. |
1 |
|
d_ext |
External model damping |
0.02 |
(was 0.02) (??) |
nwat |
No. of water species |
3 |
|
warm_start |
warm or cold start |
true |
|
n_split |
No. time splits Lagrang. dyn. |
0 |
0 = determine automatically from res. |
m_split |
No. time splits for Riemann solver |
0 |
NH dynamics |
k_split |
No. time splits for Remapping |
1 |
|
q_split |
No. time splits for Tracer Transport |
0 |
|
m_riem |
Time scheme for Riem solver subcycling |
0 |
NH dynamics |
k_top |
Starting layer for non-hydrostatic dynamics |
1 |
NH only |
a2b_ord |
interp. order from A to B Grid (corners) |
4 |
|
c2l_ord |
interp. order from D to lat-lon A winds |
4 |
|
print_freq |
Freq. to print max/min of selected fields |
0 |
0=never, pos: every nth day, neg: every nth time step |
Finally, there are a number of binary (true/false) parameters.
Since the equivalent CAM fvc_XXX parameters have to support an
"unset" parameter state, they are integers on the CAM side
(0=false, 1=true). Again, the user should only alter these if
s/he has extensive fvcubed dycore experience.
CAM parameter |
GFDL equivalent |
definition |
default |
fvc_ |
|
|
|