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Subsections
3.20.5 A more complicated example
(in directory: verification/tutorial_cfc_offline/)
The last example demonstrated simple advection of a passive
tracer using the offline form of the MITgcm. Now we present a more
complicated example in which the model is used to explore
contamination of the global ocean through surface exposure to CFC's
during the last century. In invoking packages gchem, gmredi and cfc it
provides a starting point and template for more complicated offline
modeling, involving as it does surface forcing through wind and ice
fields, more sophisticated mixing and a time-varying forcing funtion.
The model configuration for this experiment resides under
the directory verification/cfc_offline. The experiment files
- input/data
- input/data.gchem
- input/data.gmredi
- input/data.off
- input/data.pkg
- input/data.ptracers
- input/eedata
- code/GCHEM_OPTIONS.h
- code/GMREDI_OPTIONS.h
- input/packages.conf
- code/PTRACERS_SIZE.h
- code/SIZE.h.
contain all the code customisations and parameter settings
required.
The full list of other files required becomes:
cfc1112.atm data.ptracers
data depth_g77.bin pickup.0004269600.data
data.gchem eedata
data.gmredi ice.bin pickup_ptracers.0004269600.data
data.off data.pkg tren_speed.bin
and
input_off/:
Convtave.0004248060.data GM_Kwz-T.0004248060.data uVeltave.0004248060.data
Convtave.0004248060.meta GM_Kwz-T.0004248060.meta uVeltave.0004248060.meta
Convtave.0004248720.data GM_Kwz-T.0004248720.data uVeltave.0004248720.data
Convtave.0004248720.meta GM_Kwz-T.0004248720.meta uVeltave.0004248720.meta
GM_Kwx-T.0004248060.data Stave.0004248060.data vVeltave.0004248060.data
GM_Kwx-T.0004248060.meta Stave.0004248060.meta vVeltave.0004248060.meta
GM_Kwx-T.0004248720.data Stave.0004248720.data vVeltave.0004248720.data
GM_Kwx-T.0004248720.meta Stave.0004248720.meta vVeltave.0004248720.meta
GM_Kwy-T.0004248060.data Ttave.0004248060.data wVeltave.0004248060.data
GM_Kwy-T.0004248060.meta Ttave.0004248060.meta wVeltave.0004248060.meta
GM_Kwy-T.0004248720.data Ttave.0004248720.data wVeltave.0004248720.data
GM_Kwy-T.0004248720.meta Ttave.0004248720.meta wVeltave.0004248720.meta
A single line must be added (under PARM01, between lines 6
and 7) in file input/data from the previous example
&PARM01
implicitDiffusion=.TRUE.,
&
When package GMREDI is used, the flag implicitDiffusion must
be assigned the value .TRUE. For information about MITgcm package
GMREDI see...
In this example the starting timestep nIter0 is set to
4269600 requiring model access to pickup files with the timetag
0004269600. The model will run for 4 timesteps (nTimeSteps = 4). In
this case the frequencies with which permanent and rolling checkpoints
(pChkptFreq and chkptFreq) have been set is sufficiently long to
ensure that only one from the last timestep will be written. This is
also true of the values that have been assigned to the frequency with
which dumps are written (dumpFreq) and time averaging (taveFreq) is
performed however since the model always dumps the state of the model
when it stops without error a dump will be written with timetag
0004269604 upon completion.
File input/data.off, reproduced in full below,
specifies the prefixes and locations of additional input files
required to run the offline model. Note that input/input_off
contains only as many offline files as are required to successfully
run for 4 timesteps. Where the GMREDI scheme was used in the forward
run, as here, package GMREDI must again be invoked when running
offline. In this example tracer is specified as having beeen
introduced with a non-zero starttime, at timestep 4248000.
1 &OFFLINE_PARM01
2 UvelFile= '../input/input_off/uVeltave',
3 VvelFile= '../input/input_off/vVeltave',
4 WvelFile= '../input/input_off/wVeltave',
5 GMwxFile= '../input/input_off/GM_Kwx-T',
6 GMwyFile= '../input/input_off/GM_Kwy-T',
7 GMwzFile= '../input/input_off/GM_Kwz-T',
8 ConvFile= '../input/input_off/Convtave',
9 &end
10 &OFFLINE_PARM02
11 offlineIter0=4248000,
12 deltaToffline=43200.,
13 offlineForcingPeriod=2592000.,
14 offlineForcingCycle=31104000.,
15 &end
File input/data.pkg, reproduced completely below,
specifies which MITgcm packages ( /MITgcm/pkg) are to be used.
It now invokes additional packages pkg/gmredi and pkg/gchem.
1 # Packages
2 &PACKAGES
3 useGMRedi=.TRUE.,
4 usePTRACERS=.TRUE.,
5 useGCHEM=.TRUE.,
6 &
File input/data.ptracers, reproduced completely below,
specifies parameters associated with the CFC11 and CFC12 tracer fields
advected in this example.
- Line 3
PTRACERS_Iter0= 4248000,
In this example the tracers were introduced at iteration
4248000.
- Lines 7 and 14
PTRACERS_diffKh(n)=0.E3,
Since package GMREDI is being used, regular horizontal
diffusion is set to zero.
Setting flag PTRACERS_useGMRedi(n) to .TRUE. identifies
that package GMREDI is to be used. Setting flag PTRACERS_useKPP(n) to
.FALSE. explicitly turns off KPP mixing.
Since this is a `pickup' run the initial tracer files
PTRACERS_initialFile(1) and PTRACERS_initialFile(2) aree not needed.
The model will obtain the tracer state from
pickup_ptracers.0004269600.data
1 &PTRACERS_PARM01
2 PTRACERS_numInUse=2,
3 PTRACERS_Iter0= 4248000,
4 #
5 # tracer 1 - CFC11
6 PTRACERS_advScheme(1)=77,
7 PTRACERS_diffKh(1)=0.E3,
8 PTRACERS_diffKr(1)=5.E-5,
9 PTRACERS_useGMRedi(1)=.TRUE. ,
10 PTRACERS_useKPP(1)=.FALSE. ,
11 PTRACERS_initialFile(1)=' ',
12 # tracer 2 - CFC12
13 PTRACERS_advScheme(2)=77,
14 PTRACERS_diffKh(2)=0.E3,
15 PTRACERS_diffKr(2)=5.E-5,
16 PTRACERS_useGMRedi(2)=.TRUE. ,
17 PTRACERS_useKPP(2)=.FALSE. ,
18 PTRACERS_initialFile(2)=' ',
19 &
File input/data.gchem, reproduced completely below,
names the forcing files needed in package GCHEM.
- Line 3
iceFile='ice.bin',
File input/ice.bin contains 12, monthly surface ice
fields.
File input/tren_speed.bin contains 12, monthly
surface wind fields.
1 &GCHEM_PARM01
2 iceFile='fice.bin',
3 windFile='tren_speed.bin',
4 &
Package GCHEM is described in detail in section ??
File input/data.gmredi, reproduced completely below,
provides the parameters required for package GMREDI.
1 &GM_PARM01
2 GM_background_K = 1.e+3,
3 GM_taper_scheme = 'gkw91',
4 GM_maxSlope = 1.e-2,
5 GM_Kmin_horiz = 100.,
6 GM_Scrit = 4.e-3,
7 GM_Sd = 1.e-3,
8 &
Package GMREDI is described in detail in section ??
File input/cfc1112.atm is a text file containing the
CFC source functions over the northern and southern hemispheres
annually from 1931 through 1998.
In this example code/packages.conf additionally
invokes components gchem, cfc and rmredi:
ptracers
generic_advdiff
mdsio
mom_fluxform
mom_vecinv
timeave
rw
monitor
offline
gchem
cfc
gmredi
File code/GCHEM_OPTIONS.h, specifies options for
package GCHEM. In this case defining the flag ALLOW_CFC to activate
the cfc code.
File code/GCHEM_OPTIONS.h, specifies options for
package GMREDI.
File code/PTRACERS_SIZE.h is unchanged from the
simpler example.
File code/SIZE.h is unchanged from the simpler
example.
The model is run as before and produces the files the model generates
describing the grid (prefixed Depth, DXC, DXG, hFacC, hFacS and hFacW)
as well as 2, single precision, binary files
PTRACER01.0004269600-0004269604.001.001.data and
PTRACER02.0004269600-0004269604.001.001.data and their 2 corresponding
meta files as well as a single pickup file,
pickup_ptracers.ckptA.001.001.data and its corresponding meta file
pickup_ptracers.ckptA.001.001.meta from which you could run the model
on.
Next: 3.21 A Rotating Tank
Up: 3.20 Offline Example
Previous: 3.20.4 Running The Example
Contents
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