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DVD Tools (5.05.2006)
Copying and creating DVDs is now faster, easier and more portable with new software and hardware. Instructions are provided here.
SRTM30_PLUS Topography (12.09.2005)
A 30 second global elevation (topography and bathymetry) dataset from the Scripps Institution of Oceanography (http://topex.ucsd.edu/WWW_html/srtm30_plus.html) has been made available as a single NetCDF file. Further details may be found here.
Animation with MPEG-4 (12.21.2004)
The Animation webpage has been updated with tools and suggestions on creating compact, yet portable MPEG-4 animations. DivX or MS v.2 compression may be used, and then played back on a Linux workstation with a new viewer called MPlayer, or in PowerPoint 2000/2003 on the Windows platform.
NetCDF with Python (12.10.2004)
Every GFDL system can now use what is probably the simplest NetCDF programming interface around, in Python! This interface along with examples are available in our NetCDF Utilities page. Take a look at ncx.py for a general application of this interface.
To get started, internal users (GFDL/AOS) can also see the full installation notes on Python.
Color Management (7.30.2004)
The use of our color management system (CMS) is recommended for publishing to screen or print to ensure color consistency. The CMS approximates the color reproduction of the publishing device on-screen while also encoding your work's color gamut. Simply request the device's name & model from your publisher. More information is available here.
DVD Authoring (6.30.2004)
GFDL can now author data & video DVDs up to 4.7 GB in size with DVD-R discs (Mac) or DVD+RW discs (Windows). Learn how to author and label them here.
NetCDF Tool Update: nccmp 0.4 (6.25.2004)
nccmp has been completely ported to C and now supports MPI. Learn more about it in the NetCDF Utilities page.
Analog and Digital Video Converter (6.18.2004)
New A/D conversion hardware was added to our lab to transfer S-VHS video to/from DV, so old videos can now be archived onto DVD, or new digital videos can be distributed on VHS tape. Refer to the usage instructions to learn more.
NetCDF Compare Tool: nccmp (5.10.2004)
A Perl script was written that compares two NetCDF files very quickly. Learn more about it on the NetCDF Utilities page.
MATLAB Course Material (5.01.2004)
A custom 2 part MATLAB course was prepared for GFDL, and now the material used in the classroom is available on-line or as PDF. Follow the links below. Those without a GFDL account will need to adjust their intial paths when using the example scripts.
GFDL MATLAB Course Part 1 HTML PDF Example Scripts
GFDL MATLAB Course Part 2 HTML PDF Example Scripts
NetCDF Upgrade to v. 3.5.1(4.26.2004)
The NetCDF library and Operators (known as NCO) have been updated to versions 3.5.1 and 2.9.3, respectively, on the HPCS. The previous versions were 3.5.0 and 2.7.1. Details on their enhancements and compilation may be found on the Internal Visualization website.
New 1/30° Topography Dataset (11/16/99)
A 1/30° global elevation dataset (10800x6336 gridpoints, 72°N-72°S, topography and bathymetry) from UCSD, created by David T. Sandwell, Walter H.F. Smith, et al., is available for general use. This dataset was assembled from many different sources and it provides greatly improved bathymetry over the older ETOPO5 / Terrainbase datasets. For information on other datasets, see GFDL's Datasets web page.
NetCDF
Upgrade to Version 3.4
(7/13/99)
NetCDF has been updated to version 3.4 on all platforms. The previous version was 2.4.2 on the T90's and SGI`s, and version 3.3.1 on the T3E.
It is not necessary to rewrite programs that use the version 2 interface, because the netCDF-3 library includes a backward compatibility interface that supports all the old functions, globals, and behavior. HOWEVER, you will have to recompile programs that use the version 2 interface if you are going to link them against the netCDF-3 library, due to changes in the "netcdf.inc" and "netcdf.h" files.
The major improvements in this version are:
a complete rewrite of the netCDF library (in ANSI C), significantly improving performance (~2x faster); netCDF-2 compatibility interfaces implemented on top of the new C and Fortran interfaces, so that existing programs can be relinked to the new library without change; a new Fortran interface that also provides automatic type conversions; large (>2GB) file support (with some constraints) for Crays and Irix 6.x; now possible to reserve some extra space in the file header and fixed-length sections of a netCDF file so that later additions of new variables, dimensions, or attributes may avoid copying the data ; more flexible inquiry functions; elimination of dependence on vendor XDR libraries; A couple of drawbacks:
programs linked against the new library are larger than before; errors from the *new* FORTRAN routines must now be handled by the calling program - a new routine is provided for this; For more information on the changes from version 2.4.2 to version 3.4, see:
http://unidata.ucar.edu/packages/netcdf/release-notes.html http://unidata.ucar.edu/packages/netcdf/announce-3.3.html http://unidata.ucar.edu/packages/netcdf/announce-3.3.1.html http://unidata.ucar.edu/packages/netcdf/announce-3.4.html For more information on using the new features of version 3.4, see the on-line documentation at http://unidata.ucar.edu/packages/netcdf/docs.html. If you have any questions or problems, please contact John Sheldon (jps, Rm. 125) or Hans Vahlenkamp (hnv, Rm. 126).
NCO NetCDF
Utilities Update
(6/21/99)
The NCO suite of netCDF operators has been updated from version 1.1.28 to version 1.1.33. This version adds the following capabilities:
index-based hyperslabbing across files in the record dimension in the multi-file operators ncra and ncrcat, e.g., ncra -d time,1,100 in1.nc in2.nc ... out.nc stride for the record dimension in ncra and ncrcat, e.g., ncra -d time,1,100,12 in1.nc in2.nc ... out.nc In addition, the default behavior of ncks is now to alphabetize the variables in the output file. To retain the old behavior, use the "-a" switch.
nrecreset NetCDF Utility (6/14/99)
This utility forcibly resets the number of records in a netCDF file to the desired value. The main use for this utility is when a job terminates abnormally and does not close the file properly, in which case the data may be present in the file, but the metadata will indicate too few (or no) actual records.
NCO NetCDF
Utilities Fix
(4/29/99)
The NCO suite of netCDF operators has been updated from version 1.1.25 to version 1.1.28. This version fixes a bug introduced in version 1.1.25, which caused ncrcat to get a "Floating exception" under many circumstances.
Recall that these utilities can be found in ~jps/pub/netcdf/util/bin/, on either the Crays or SGI's. (Not all of them are documented yet in our "NetCDF Utilities" page, but you can get everything you need to know about them from the "NCO User's Guide".)
NCO NetCDF
Utilities Update
(4/21/99)
The NCO suite of netCDF operators, written by Charlie Zender at NCAR, has been updated (from version 1.1.22 to version 1.1.25). This version fixes a bug with ncra and ncrcat which could, under some circumstances, cause the last record of a coordinate variable to be omitted from the output file (ncrcat) or not included in the average (ncra). (This could occur when FORTRAN-indexing (-F) was specified AND user-specified hyperslab information was provided for some dimensions BUT not for the record dimension.)
Enscript - PostScript Printout with Color Syntax Highlighting (3/25/99)
GNU Enscript is a utility that converts text files into PostScript for printing, similar to a2ps. However, Enscript has many more options, most significant of which is the ability to do color syntax highlighting of program code for many different languages. Printing of highlighted text can already be done directly out of Emacs, so Enscript is probably most useful for those using other text editors, particularly NEdit.
For more information, see the instructions for getting started with Enscript, which includes some examples.
NCO NetCDF
Utilities Update
(3/11/99)
The NCO suite of netCDF operators, written by Charlie Zender at NCAR, has been updated (from version 1.1 to version 1.1.22). The operators are:
ncatted - netCDF Attribute Editor ncdiff - netCDF Differencer ncea - netCDF Ensemble Averager ncecat - netCDF Ensemble Concatenator ncflint - netCDF File Interpolator ncks - netCDF Kitchen Sink ncra - netCDF Record Averager ncrcat - netCDF Record Concatenator ncrename - netCDF Renamer ncwa - netCDF Weighted Averager All of these utlities can be found in ~jps/pub/netcdf/util/bin/, on either the Crays or SGI's. Sorry, not all of them are documented yet in our "NetCDF Utilities" page, but you can get everything you need to know from the "NCO User's Guide".
Several changes have been made since the previous version installed at GFDL:
now built using netCDF 3.4, which should execute faster ncwa modified to run faster, though it uses more memory improved error diagnostics added "-h" option to supress "history" concatenation; changed exisiting ncks -h" option to "-m" (the mnemonic is `metadata') several bug fixes, including one in ncks which prevented "merging" of variables from different files lots of changes to ncwa, including removal of the `-n' and `-W' normalization options, possibly permanently, but at least until their implementation is simplified and redesigned No, there is still no support for arithmetic on "packed" data (though we're looking into it!) A Warning has been issued by the author regarding problem behavior under IRIX, and he has some suggested workarounds. For more details, see the NCO News and the ChangeLog
Please let us know if you have any problems with any NCO utilities.
New Datasets Web Page, Featuring 1/12° Topography Dataset (3/4/99)
A new web page has been created to provide information about datasets available to users at GFDL. Anyone with datasets they wish to make available for general use should contact John Sheldon or Hans Vahlenkamp to have it added to the page.
At present, this new web page features only the 1/12° (4320x2160 gridpoints) global elevation (topography and bathymetry) TerrainBase dataset announced some time ago (October 1996). See the GFDL TerrainBase web page for more information, plus a couple of impressive visualizations of the data.
NEdit Text Editor - With Syntax Highlighting! (4/22/98)
NEdit is polished GUI text editor which will be bundled with IRIX 6. It is nearly as simple as Jot and and offers some of the nicer features of Emacs, most notably the extremely useful color syntax highlighting , which works for FORTRAN, C, C-shell, and many other programming languages. NEdit's interface is intuitive (it uses SGI's enhanced Motif widgets) and nteractively customizable.
[Another notable feature of NEdit is the ability to copy text out of the NEdit window and then paste it into Netscape Gold's web-page editor window. This seems to be the only way to bring arbitrary (non-HTML) text into that editor. ]
See the instructions for getting started with NEdit (some Xdefaults and a small start-up file for your home directory).
NCCATM
Upgrade-
Efficiency and diagnostics (3/16/98)
Internal loop ordering has been changed and Cray FFIO layering is specified internally in order to optimize performance on the T90. (The user may override the nccatm-specified FFIO layer via a command line option, but this is not recommended.) These changes should result in better turnaround time and less stress on the T90 system.
Also, "verbose" and "quiet" switches have been added to help control the amount of diagnostic output while running.
grads2nc
Conversion Utility 
(Added
3/13/98)
A new utility, grads2nc, for converting GrADS data files to netCDF has been installed. Not all GrADS features are supported, and the netCDF files created are less than complete because GrADS files lack some information typically included in netCDF files. Nevertheless, "grads2nc" provides a means for users with GrADS data to take advantage of the many available tools for handling and visualizing netCDF data.
NCCATM
Upgrade-
Time coordinate consistency (Added 2/6/98)
The netCDF file concatenation utility, nccatm, has been enhanced to handle the concatenation of files whose time-axis units do not match. This can happen when you have, say, one file with units of "days since 1980-01-01" and a second with units of "days since 1981-01-01". If each file has time-coordinates which run "1,2,3,...365", blindly concatenating them would yield time-coordinates of "1,2,3,...365,1,2,3...365". nccatm instad converts the time coordinates of the second file to the units of the first, yielding continuous, monotonic coordinates of "1,2,3,...365,366,367,...730". Please let us know how it works for you.
New
NCVIEW (Added
11/19/97)
A new version of "ncview" (version 1.71) has been installed. The author was kind enough to make some very quick fixes to accomodate us:
added an option to filter out 1-D variables ("-no1d") - useful in eliminating "time-average"-documenting variables geography will now plot properly for longitudes from -180 to 0 the plot shows up properly without having to resize the window (mostly...) the "Range...Reset to global" option works again the "Range...Symmetric about 0" now works
New
NCVIEW (Added
11/17/97)
A new version of "ncview" (version 1.70) has been installed. For those of you unfamiliar with it, "ncview" is a very handy visual browser for netCDF files. Typically you would use ncview to get a quick and easy, push-button look at your netCDF data using color-filled contours. You can view simple movies of the data, view along various dimensions, take a look at the actual data values, change color maps, invert the data, etc.
Important new features with version 1.65 include :
Optional map overlay Pop-up line graph can use any of the coordinates as the X-axis A bug in the print option has also been fixed.
NCAVG
Upgrade -
Larger Variables (Added 4/29/97)
The netCDF file averaging utility ncavg (current version=1.3,beta1) has been upgraded to handle larger variables, with the averaging now taking place one 2-D slab at a time, instead of for an entire 3-D volume. There is still a size limit of 320,000 points per horizontal slab, but this is a large increase over the previous version.
- Other changes:
- fixed a bug in how occasional "missing_value" points were handled during the averaging process. (Points which were always missing were handled properly, eg, land masks.)
- variables which do not utilize the "record" dimension (ie, "time") are passed directly through to the output file.
- added a "silent" option to eliminate diagnostic output
- now handles non-floating-point data variables (ie, ignores them)
Please let us know how ncavg works for you!
New
NetCDF Utilities (Added
4/3/97)
A new set of utilities, written by Charlie Zender at UCAR, has been added which will aid in the manipulation and analysis of NetCDF data:
Of particular note is ncrcat, which can perform most of the functions of ncks, but does not have the same memory limitations which caused problems when extracting very large variables and/or long time series.
NCAVG
Upgrade -
"Equal weighting" option (Added 4/2/97)
The netCDF file averaging utility ncavg now has a new option, "-eq", which forces equal weighting of all points along the record (time) axis. The default method is to use the trapezoidal rule, which will more "accurately" handle endpoints, unevenly spaced time coordinates, and duplicated points, but there may be cases where equal weighting is more appropriate or "traditional". In addition, the new version will now handle larger variables (though it still needs to be made more flexible).
NCCATM
-
Multiple netCDF file concatenation (Added 3/10/97)
A version of the netCDF file concatenation utility, nccat, has been added which extends this capability, previously limited to 2 files, to multiple files. The new utilty, nccatm, will handle an arbitrary number of input files, but is otherwise identical to nccat (ie, it still overwrites the first file in the list). This should significantly speed up scripts involving concatenation of many individual files, to say nothing of making the scripting far easier and clearer. We expect nccatm will replace nccat soon (perhaps with some addtional options). Please let us know how it works for you.
Visualization Gallery (Added 2/28/97)
A number of interesting visualizations which have been developed over the past couple of years have been assembled into "gallery" of sorts, which is (as usual) still "under construction". These are offered not so much as scientific research results, nor do they necessarily represent the spectrum of research being conducted at GFDL, but rather as examples of various visualization techniques and how they might be used to convey complex results as (hopefully) understandable images and animations. Suggestions for additions to this list are welcome!
NCAVG
NetCDF Time-Averaging Utility (Added
2/26/97)
A new utility for calculating time-averages of netcdf file(s) has been installed. Its function is very narrow in scope, but should directly address a common need. Let me know how it works for you and if you have any suggestions!
NetCDF Interface Routines (NCIR) Version 0.7 Official (Added 2/7/97)
Version 0.7 of GFDL's local NetCDF Interface Routines (NCIR) have been installed, following a trouble-free beta testing period. Only a few modifications were made to eliminate some compiler warnings and to reduce some diagnostic printout. Now, on to the next version!
Guide to using Ferret at GFDL(Added 1/28/97) No longer available
Keith Dixon has put together a couple of nice web pages giving an overview of how to get started using FERRET here at GFDL, and has provided links to the "Official" FERRET Web Pages. The two primary pages in his guide are:
Ferret Background Info
Setting up the Ferret SGI Workstation Environment
Search Engine 
(Added 1/23/97) Please use the search box in the upper-right corner of your browser.
Hans Vahlenkamp has created a simple search engine which can be used to locate items in GFDL's Scientific Visualization Guide based on a simple search for one or more keywords. It's no "Alta Vista", but it could come in real handy when you can't remember where you saw something. Try it out and let us know what you think.