| ⚠️ WARNING: Maintenance-only mode until around the end of 2023.          |
| :------------------------------------------------------------------------------ |
The CDAT library is now in maintenance-only mode, with plans for deprecation and cease of support around the end of calendar year 2023. Until this time, the dependencies for specific CDAT packages (`cdms2`, `cdat_info`, `cdutil`, `cdtime`, `genutil`, `libcdms`) will be monitored to ensure they build and install in Conda environments. We currently support Python versions 3.7, 3.8, 3.9, and 3.10. Unfortunately, feature requests and bug fixes will no longer be addressed.|
If you are interested in an alternative solution, please check out the [xarray](https://docs.xarray.dev/en/stable/index.html) and [xCDAT - Xarray Extended With Climate Data Analysis Tools](https://github.com/xCDAT/xcdat) projects.|

***************************

EzGet Summary

***************************

You have acquired from the Program for Climate Model Diagnosis and
Intercomparison (PCMDI) software known as EzGet, which facilitates
retrieval of data stored in popular formats (including DRS, netCDF,
GrADS, and if a control file is supplied, GRIB).  EzGET (pronounced
easy-get) is specifically designed to access climate data and climate
model output.  You can specify how the data should be structured and
whether it should  undergo a grid transformation before you receive it,
even when you know little about the structure of the stored data
(i.e., its dimension order, grid, and domain).

EzGet comprises a set of subroutines that can be linked to any FORTRAN
program.  EzGet reads files through the cdunif interface, but use of
EzGet does not require familiarity with cdunif.  The main advantages of
using this software instead of the lower level cdunif library include:

   * Substantial error trapping capabilities and detailed error messages

   * Versatile capability of conveniently selecting data from specified
     regions (e.g., oceans, North America, all land areas north of 45
     degrees latitude, etc.)

   * Ability to map data to a new grid at the time it is retrieved by
     EzGet

   * Automatic creation of ``weights'' for use in subsequent averaging
     or masking of data

   * Increased control in specifying the domain, grid and structure of
     the retrieved data.

Taken together these capabilities will simplify the process of writing
programs for accessing data stored in different formats and structures,
including all the observed data sets and the model output from various
model intercomparison projects (AMIP, PMIP, CMIP, etc.) archived at
PCMDI.

EzGet software and documentation are are available through the PCMDI
web site:

   home page: http: //www-pcmdi.llnl.gov/
   EzGet location: http://www-pcmdi.llnl.gov/ktaylor/ezget/ezget.html

The software currently is available for the following
platforms/operating systems:

Sun/SunOS 4.1.3
Sun/Solaris 2.4
IBM RS6000/AIX 3.2
HP/HP-UX 9.0
SGI IRIX 5.3
Macintosh OS X

It should also be available shortly on:
Cray/Unicos
DEC Alpha/OSF



***************************

Installation

***************************

Obtain from the PCMDI web site the tarred and compressed file
containing the EZGET, DRS and cdunif libraries appropriate to the
platform (computer) you will be using along with documentation,
geography data from AMIP models, examples and sample data.

You should uncompress the tar files.  For example for the HP version
enter:

uncompress ezget1.1.3_doc.tar.Z
uncompress amip_geog.tar.Z
uncompress ezget_examples.tar.Z
uncompress ezget1.1.3_hp.tar.Z

Then you should extract the files from the tarred library files,
examples files, and document files.  For example for the HP version
enter:

tar -xvf ezget1.1.3_doc.tar
tar -xvf amip_geog.tar
tar -xvf ezget_examples.tar
tar -xvf ezget1.1.3_hp.tar

You should now have the following files in your directory:

3 fortran libraries:

     libcdms.a
     libdrs.a
     libezget.a


Documentation:

        README
        colorgeog.ps
        ezget.ps
        ezget.pdf (if you downloaded the pdf tar file)
        ezget.tex (if you downloaded the tex tar file;  this is
               the ascii file that latex uses to create ezget.ps)


Geography data for AMIP models:

        sftbyrgn_bmr.dat
        sftbyrgn_bmr.dic
        sftbyrgn_ccc.dat
        sftbyrgn_ccc.dic
        sftbyrgn_cnr.dat
        sftbyrgn_cnr.dic
               .
               .
               .
               .
        sftbyrgn_ukm.dat
        sftbyrgn_ukm.dic
        sftbyrgn_yon.dat
        sftbyrgn_yon.dic


Sample programs:

      4738 Mar 22 14:28 areamean.f
     12443 Mar 22 14:28 extract.f
      3894 Mar 22 14:28 extract_shrt.f
      5761 Mar 22 14:27 getregn.f
      5472 Mar 22 14:28 maxmin.f
      5499 Mar 22 14:28 meandiff.f
      6493 Mar 22 14:28 regrding.f
      8638 Mar 22 14:28 rmscalc.f
      5820 Mar 22 14:28 smmaxmin.f


Input data (DRS format) for sample programs:

   1589760 Feb  2 11:18 nasa-amip_t.dat
      1536 Feb  2 11:18 nasa-amip_t.dic
     13312 Feb  6 15:49 sftbyrgn_gla.dat
      1536 Feb  6 15:49 sftbyrgn_gla.dic


If you will be reading netCDF files, you will need to acquire the
netCDF library from the web site:

ftp://ftp.unidata.ucar.edu/pub/netcdf/

Once you have placed the libraries where you want them, you may have to
execute "ranlib" on some platforms:

ranlib libcdms
ranlib libdrs
ranlib libezget
ranlib libnetcdf

A surface air temperature data set and a detailed geography mask in DRS
format are included in the examples file.  All the examples (documented
in the ezget.ps file) should run on your platform, except rmscalc.f,
which requires input files from 30 different models.  Before compiling
and running these sample applications, you will need to edit the files,
specifying the correct paths to the input data  (check all the calls to
subroutine defvar).

For various platforms, typical lines for compiling and linking to the
libraries are given here (you will need to change the path to the
libraries):

Sun/SunOS:
f77 extract.f -L$PCMDI/Sunos/lib -lezget -lcdms -ldrs -lnetcdf -o extract

Sun/Solaris
f77 extract.f -L$PCMDI/Solaris/lib -lezget -lcdms -ldrs -lnetcdf -o extract

IBM RS6000/AIX
xlf extract.f  -L$PCMDI/Ibm/lib -lezget -lcdms -ldrs -lnetcdf -o extract

HP/HP-UX
fort77 +U77 extract.f -L$PCMDI/Hp/lib -lezget -lcdms -ldrs -lm -lnetcdf \
      -o extract

SGI
f77 extract.f -L$PCMDI/Sgi/lib -lezget -lcdms -ldrs -lnetcdf -o extract



*************************************

Bugs, Updates, and Limitations

*************************************


*************
EzGet Bugs
*************

Bugs in Version 1.0:  A rarely encountered bug was discovered that
sometimes caused an EzGet internal table (where dimension information
is stored)  to fill up prematurely.  This bug would be obvious to any
user who encountered it and was corrected in version 1.1.2.  Another
bug was found which affects masking of geographical regions.  If a
geography mask were stored with more than the longitude and latitude
dimensions explicitly defined (e.g., if the mask were a function of
time), but if in fact this third dimension contained only one element
(i.e., "time" might actually only be a dummy dimension and therefore
the data stored would only be 2-dimensional), and if the field that
EzGet was instructed to mask was in fact a function of time, then EzGet
will obtain masking information for most of the field from some
unpredictable location in the computer's memory and garbage will be
produced, which may or may not be evident to the user.  This bug was
corrected in Version 1.1.3.

Bugs in Version 1.1: Several bugs were found having primarily to do
with masking geographical regions under the newly implemented option to
use land fraction data (expressed as a percentage).  The worst problem
found was that land data would be masked when ocean data should have
been masked and vice versa. Most of these bugs were corrected in
Version 1.1.2.  Also the second bug found in Version 1.0 remained in
Version 1.1, but was corrected in Version 1.1.3.

Bugs in Version 1.1.2: Two bugs related to the newly implemented
option to use land fraction data (expressed as a percentage) were
discovered.  Also the second bug found in Version 1.0 remained in
Version 1.1.2.  All of these bug were corrected in Version 1.1.3.

Bugs in Version 1.1.3:  No bugs have been reported in the most recent
release of EzGet (Version 1.1.3; 19 December 1996).  Users should
report suspected bugs to taylor13@llnl.gov.  Also all users should
register by email at taylor13@llnl.gov, indicating name, location, and
platform, so that they can be immediately informed if significant bugs
are found.  New releases of EzGet will be announced by email to all
those registered.


*************
EzGet Updates
*************

Version 1.0 was the original version of EzGet to be publicly released
in March 1996.  It had been thoroughly tested at PCMDI over a two year
period.

Version 1.1 was released in September 1996.  Programs using version 1.0
should run successfully under version 1.1, but the newer version
differs in the following respects:

* The capability for selecting (or masking) data from specific
geographical regions was extended so that output from the Atmospheric
Model Intercomparison Project 2 (AMIP 2) and Paleoclimate Modeling
Intercomparison Project (PMIP) could be used in unmodified form.  In
addition to the types of geographical data that were previously
permitted, version 1.1 makes it possible for EzGet to read land
fraction data (expressed as a percent) or sea ice fraction data
(expressed as a percent), making it easy to mask out  data from land,
ocean or sea ice regions in analyses of the intercomparison project
output.  In addition, when data is extracted, for example, from land
areas only, the weights created by EzGet, which can be used to
calculate area averages, are properly generated even for models in
which individual grid cells are partly land and partly ocean.  See
documentation of subroutines defgeog, getgeog, and defmisc for further
details.

* The capability of extracting integer data was expanded by allowing
for proper identification of missing integer data.  See documentation
of subroutine defmisc for further details.

* A bug in the assignment of aliases for the longitude and latitude
coordinates (accomplished through calls to subroutine defmisc) was
corrected.  See documentation of subroutine defmisc for further
information.

* The assignment of weights for the LMCE and LMD models was corrected
and generalized to allow for different model resolutions.

* In calls to subroutine defdim, EzGet now recognizes that the model
acronym 'ech*' (where * can represent any group of characters)
indicates a gaussian grid. See appendix A of the documentation.

* A bug was found and corrected, so that EzGet now correctly recognizes
the equivalence of the strings, 'sea ice', 'sea-ice', and 'seaice',
which are used to select data from regions with sea ice.  If this bug
was encountered in the previous version, an explicit error message
would be written so the user would have known about it.

* Documentation was updated to account for all these changes.
Significant changes were made in the sections on subroutines defgeog,
demisc, and getgeog.



Version 1.1.2 was released in 11 November 1996.  It differs from
Version 1.1 in the following respects:

* A few bugs were corrected, primarily having to do with masking
geographical regions under the newest option to use land fraction data
(expressed as a percentage).  The worst bug was that in version 1.1
land data would be masked when ocean data should have been masked and
vice versa. Also an option is now available to specify explicitly that
the geography data set contains land fraction data (expressed as a
percentage).  See documentation of subroutine defmisc for further
details.

* A bug involving an internal dimension table created by EzGet was
corrected, which makes it less likely that this table will become
filled.



Version 1.1.3 was released in 9 December 1996.  It differs from
Version 1.1.2 in the following respects:

The two bugs described at the beginning of this page were eliminated.  </li>


**********
EzGet limitations:
**********

Current limitations include:

* EzGet has not been ported to the Cray or DEC Alpha computers.

* The full capabilities of EzGet apply only to 4-byte floating point
(real*4) data. Double precision and integer data, for example, cannot
be interpolated to new grids within EzGet.

* The names of fields that will be extracted by EzGet should be no
longer than 16 characters long.  (All standard names for AMIP and PMIP
are shorter than 16 characters, but EzGet would not be able to extract,
for example, a field named 'sea_level_pressure' because it is too
long.)

* Coordinates are converted to single precision when extracted by
EzGet, and currently it is only possible to specify the domain of data
to be extracted in single precision.  This may lead to problems if, for
example, the time  domain of some hourly data you want to extract is
for years 1000 through 1001 (i.e. hours 8,760,000 through 8,768,760).
Single precision floating point numbers are unable to resolve 1 part in
8.7x10**6, so it would not be possible to properly extract this data by
specifying a domain with subroutine defdim.  (Note, however, subroutine
defdimi could be used to specify  a domain and retrieve the data
successfully, but if it were necessary to retrieve the coordinate
values  getcoord), they would be truncated.

* Geography maps used to specify regions such as "North America",
"Australia", "South Pacific", etc. are currently available for AMIP 1
models, but they are not yet available for all PMIP, CMIP, or AMIP 2
models.


***************************

Software Support

***************************

If you have questions contact:

TAYLOR Karl E.		Lawrence Livermore National Laboratory
			P.O. Box 808, L-264
			Livermore, CA 94550
                or (for Federal Express)
                        L-264
                        7000 East Ave.
                        Livermore, CA 94550

		Tel.:	1 (510) 423-3623
		Fax.:	1 (510) 422-7675
		email:	taylor13@llnl.gov