The CCSM2.0 Quick Start Guide

www.ccsm.ucar.edu

The CCSM2.0 Quick Start Guide

Lawrence BujaCCSM Software Engineering Group

[email protected] 29 2002

www.ccsm.ucar.edu

CCSM2.0 Quick Start Guide

• What is needed to run CCSM2?• Downloading the CCSM2.0 distribution• The CCSM source code• Input datasets • Building the CCSM• Running the CCSM • CCSM output data

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What is needed to run CCSM2?

• OS: IBM AIX or SGI IRIX64• Compilers: Fortran 90, C • Tools: gunzip, gnumake, Perl5, Perl/Tk• Permanent & Temporary disk space• Libraries: MPI and netCDF • Input data : 0.2 GB for T31_gx3 grid,

0.8 GB for T42_gx1v3 grid

• CCSM2 source code: 35 MB

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The CCSM2.0 distribution

CCSM2.0 is available via the web from: http://www.cgd.ucar.edu/csm/models/ccsm2.0

ccsm2.0.tar.gz CCSM2.0 source codes ccsm2.0.inputdata.T42_gx1v3.tar input data for T42_gx1v3 resolution ccsm2.0.inputdata.T31_gx3.tar input data for T31_gx3 resolution ccsm2.0.inputdata.T62.tar latm data for T62 resolution ccsm2.0.inputdata.CLM_SPINUP_FILES.tar are CLM datasets

gunzip -c ccsm2.0.tar.gz | tar -xf -

tar -xf ccsm2.0.inputdata.T42_gx1v3.tar

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The CCSM distribution

$HOME/

ccsm2.0/$CSMROOT

/fs/$LOGNAME/

inputdata/$CSMDATA

ccsm2.0.tar.gz

(35 Mbytes)

Scripts & Model Code

ccsm2.0.inputdata.T42_gx1v3.tar

(.8 Gbytes )

Initial data

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The CCSM source code: inputdata/

cp l5 /

cp l/

cam 2/

datm 5/

la tm 5/

atm /

pop /

docn5/

ocn/

cs im 4/

dice5/

ice /

clm 2/

dlnd5/

lnd /

inputdata/

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The CCSM source code: Top Level

doc/docum enta tion

m odels/m odel source code

scrip ts /bu ild /run Scrip ts

ccsm 2.0/C C SM 2.0 R oot D irectory

$H O M E /

($CSMROOT)

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The CCSM source code: models/

cp l5 /

cp l/

cam 2/

datm 5/

la tm 5/

atm /

pop /

docn5/

ocn/

csim 4/

d ice5/

ice /

clm 2/

d lnd5/

lnd / b ld / shr/

$C SM R O O T /m odels/

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The CCSM source code: scripts/

test.a1/ gui_run/ too ls /

$C C S M R O O T /scrip ts /

test.a1.runcpl.setup.cshatm.setup.cshocn.setup.cshice.setup.cshlnd.setup.cshdatm.setup.cshdocn.setup.cshdice.setup.cshdlnd.setup.cshccsm_archivetest.a1.har

ccsm_checkenvsccsm_cpdataccsm_getfileccsm_getinputccsm_getrestartccsm_msmkdirccsm_msreadccsm_mswriteccsm_splitdfmodules.AIX.seaborgmodules.IRIX64.nirvanamodules.IRIX64.utetest.a1.mods.*

ccsm_gui.pl

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Building the CCSM Three levels of c-shell scripts are used:

– Run script builds & runs CCSM (i.e. test.a1.run)– Define the CCSM environment– Run each component setup script– Execute all components simultaneously

– Setup scripts builds each model (i.e. ice.setup.csh)– Position any input data needed by that component– Generate the component's namelist input file – Build the component executable

– Utility tools (i.e. ccsm_getinput)

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Building the CCSM

A sample run script (test.a1.run) is distributed.Functional summary of test.a1.run

setenv A abc setenv B xyzforeach i (cpl atm ocn ice lnd)

$i.setup.cshendmpirun cpl atm ocn ice lndexit

Loop over setup scripts

Define environment

Run CCSM

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Building the CCSM: $CASE

$CASE identifies a CCSM run. The sample $CASE is test.a1,$CASE for the CCSM control run is b20.007

To define a new $CASE– Copy all of test.a1/ into $CASE/– rename test.a1.run to $CASE.run– Modify the main run script

– CASE CASESTR CSMROOT CSMDATA EXEROOT ARCROOT

– $HOME/ccsm2.0/scripts/$CASE/$CASE.run submitted to the batch queue.

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Building the CCSM

$HOME/ccsm2.0/$CSMROOT

/fs/$LOGANME/inputdata/$CSMDATA

Scripts & Model Code Initial data

/ptmp/$LOGNAME/$CASE$EXEROOT

Large model build/execute directories

doc/ models/ scripts/

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Methods for starting the CCSM

New CCSM case is started as either a startup, hybrid or branch run, depending on the science requirements.

startup: new run from arbitrary input fileshybrid:new run from initial or restart filesbranch: new run from restart files continue: extend an existing run exactly

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General concepts: Exact Restarts

• Wall-clock limits in the batch queues typically restrict runs to a finite length, usually 1-3 model years.

• At specified intervals, restart and initial files will be created by all components

• Runs are extended as "continue" runs.• A continued run must give exactly the same results

as if the run had never stopped.

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Are your results reproducible?

Factors: •Any change in machine architecture•Any change in math libraries•Running on different number of processors•Changes you've made to the code•Additional variables added to model not

properly written to restart files

Exact Restarts

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Changing the codeFrozen Code

Keep the CCSM2.0 model code "frozen"To introduce code changes:

• copy specific model files to new directory• modify the new copies of model code• tell the model setup scripts to get the modified

code from the new directory first, then get rest of unchanged model code from the "frozen" version

This method encapsulates modified codeUse same "frozen code" for different work

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Changing the code

Three levels of change:1. "Bit-for-bit" (no change to answers)

• adding/subtracting output

2. Machine-level (answers similar at the bit level) • Changes in operation order• Changes in math libraries• changes in compiler options/flags/versions

3. Algorithm changes (answers change)• Different parameterization• Rerun control integration

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atm

ocn

icelnd Coupler

CCSM Components

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CCSM2: PerformanceOCN

ICE

LND

ATM

CPL

8 3 7

8 37

7 4

3 7 2 14

41secs

53 secs/day total (~130 years/month)

NERSC T42/gx1v3 (128Pes)

32

8

8

32

48

Critical path

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Output log files

• The printed output from each CCSM component is saved in a "log file" A coordinated timestamp links filenames

$LID is of the form YYMMDD-hhmmss, where YYMMDD are the Year, Month, Day and hhmmss are hour, minute and second that the run began (i.e. $EXEROOT/ocn/ocn.log.000626-082714) .

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History and restart output data

• Default: netCDF monthly averaged history files for all components in netCDF format.

• CCSM2.0 also writes out binary restart files from all components at regular intervals.

• The total output volume of the model output can vary greatly depending upon the output frequencies and options selected.

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TapeArchive Device

cpl

atm

ocn

icelnd

1.4 Gbytes

0.7 Gbytes

4.1 Gbytes

.6 Gbytes .4 Gbytes

disk

disk

disk

TapeArchive Devices

7.4 Gbytes/year

CCSM Yearly Output (b20.014)

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Getting help

• http://www.ccsm.ucar.edu forum• [email protected]