cmip3

Translating CMIP3 to CMIP5

The script translate_cmip3 converts the CMIP3 archive into a form as close to the DRS specification as possible. This transformation involves both filename and directory structure changes. From the command's help message:

Usage: translate_cmip3 [options] cmip3_root cmip5_root
Options:
-h, --help            show this help message and exit
-i INCLUDE, --include=INCLUDE
Include paths matching INCLUDE regular expression
-e EXCLUDE, --exclude=EXCLUDE
Exclude paths matching EXCLUDE regular expression
-c, --copy            Copy rather than move files
-d, --dryrun          Emit log messages but don't translate anything
-l LOGLEVEL, --loglevel=LOGLEVEL
Set logging level

Example

The drslib.cmip3 module implements a similar API to drslib.cmip5 thus allowing CMIP3 paths to be converted to DRS instances then converted into CMIP5 DRS format.

>>> from drslib import cmip3
>>> cmip3_trans = cmip3.make_translator('cmip3')
>>> drs3 = cmip3_trans.filepath_to_drs('cmip3/20c3m/atm/da/rsus/gfdl_cm2_0/run1/rsus_A2.19610101-19651231.nc')
>>> drs3
<DRS activity='cmip3', product='output', institute='GFDL', model='CM2', experiment='20c3m', frequency='day', realm='atmos', variable='rsus', table='A2', ensemble=(1, None, None), version=1, subset=None, extended='19610101-19651231'>
>>> cmip5_trans.drs_to_filepath(drs3)
'http://example.com/cmip5/output/GFDL/CM2/20c3m/day/atmos/v1/rsus/r1/rsus_A2_CM2_20c3m_r1_19610101-19651231.nc'

CMIP3 DRS components

The CMIP3 activity is cmip3 and all datasets are given the product output. The version component is always v1. Translation of the other DRS components for CMIP3 are described below.

Institute & Model

Institutes and models given in capital letters and underscores are converted to dash characters. Capitalisation is chosen to be consistent with the examples given in sections 3.2 and 3.3 of the DRS specification and dashes are used to avoid ambiguity in DRS filenames that use underscores as the component separator.

Where the exact encoding is not trivial the syntax used by the IPCC Data Distribution Centre [DDC] is used.

[DDC]

http://www.ipcc-data.org

CMIP3 directory	Institute	Model
bcc_cm1	CMA	BCC-CM1
bccr_bcm2_0	BCCR	BCM2
cccma_cgcm3_1	CCCMA	CGCM3-1-T47
cccma_cgcm3_1_t63	CCCMA	GCM3-1-T63
cnrm_cm3	CNRM	M3
miub_echo_g	MIUB-KMA	CHO-G
csiro_mk3_0	CSIRO	K3
csiro_mk3_5	CSIRO	K3-5
gfdl_cm2_0	GFDL	M2
gfdl_cm2_1	GFDL	M2-1
inmcm3_0	INM	M3
ipsl_cm4	IPSL	M4
iap_fgoals1_0_g	LASG	GOALS-G1-0
mpi_echam5	MPIM	CHAM5
mri_cgcm2_3_2a	MRI	GCM2-3-2
giss_aom	NASA	ISS-AOM
giss_model_e_h	NASA	ISS-EH
giss_model_e_r	NASA	ISS-ER
ncar_ccsm3_0	NCAR	CSM3
ncar_pcm1	NCAR	CM
miroc3_2_hires	NIES	IROC3-2-HI
miroc3_2_medres	NIES	IROC3-2-MED
ukmo_hadcm3	UKMO	ADCM3
ukmo_hadgem1	UKMO	ADGEM1
ingv_echam4	INGV	CHAM4

Experiment

The experiment component remains unchanged from the CMIP3 archive structure except that its position in the tree changes to match the DRS specification.

Frequency

The CMIP3 frequency specifiers are translated into those described in the DRS specification as follows:

CMIP3	DRS
yr	yr
mo	mon
da	day
3h	3hr
fixed	fx

Modelling-realm

We map CMIP3 realms onto equivilent CMIP5 realms. In some cases this mapping also depends on the variable. This mapping is defined in the table below:

CMIP3 realm	Variable	DRS realm
atm	mrsos	land
atm	trsult	aerosol
atm	trsul	aerosol
atm	tro3	atmosChem
atm	*	atmos
ice	*	seaIce
land	sftgif	landIce
land	*	land
ocn	*	ocean

Variable name

Variable names are left unchanged.

Ensemble member

The encoding run<N> is translated into r<N>.

Subset and extended path

Although most filenames in the CMIP3 archive follow a consistent syntax there are enough exceptions to make complete adherence to the DRS specification impractical. Instead translate_cmip3 attempts to extract the variable, MIP table name from the CMIP3 path and constructs an approximate DRS filename of the form:

<variable>_<mip-table>_<model>_<experiment>_<ensemble-member>_<extended>.nc

where <extended> is the unparsed portion of the filename that may contain a temporal subset or may be irregular. Some examples are given below:

/20c3m/atm/da/rsus/gfdl_cm2_0/run1/rsus_A2.19610101-19651231.nc --> rsus_A2_CM2_20c3m_r1_19610101-19651231.nc
/1pctto2x/atm/mo/rlftoaa_co2/ipsl_cm4/run1/rlftoaa_co2_A5_1860-1869.nc --> rlftoaa_co2_A5_CM4_1pctto2x_r1_1860-1869.nc
/2xco2/land/fixed/orog/miroc3_2_hires/run1/orog_A1.nc --> orog_A1_MIROC3-2-HI_2xco2_r1.nc
/sresa1b/atm/mo/rlut/cccma_cgcm3_1/run4/rlut_a1_sresa1b_4_cgcm3.1_t47_2001_2100.nc --> rlut_a1_CGCM3-1-T47_sresa1b_r4_sresa1b_4_cgcm3.1_t47_2001_2100.nc