Introduction to EdGCM
Welcome to EdGCM, an integrated software suite designed to simplify the process of setting up, running, analyzing and reporting on global climate model simulations. The software package includes a full copy of 4th Dimension® database software (4D, Inc.) and the NASA/Goddard Institute for Space Studies’ Global Climate Model II (i.e., GISS GCM II). The GISS GCM II is currently in used for climate research at NASA labs and several universities. For a complete description of the GISS GCM II see Hansen et al., 1983, included inside EdGCM’s doc folder.
EdGCM includes everything you need to begin exploring climate science using a research quality computer climate model. Despite the complexity of the underlying GCM, the EdGCM interface and associated utilities will allow the model to be operated and managed by teachers, students, and researchers with minimal training. Please note, however, that this is a beta version with limited documentation, so if you have not already attended one of our training workshops you may have difficulty utilizing the many functions available in this package. You are welcome to contact us for help in getting started, but we are currently only offering significant support to institutions that are collaborating with us for evaluation purposes. If you would be interested in attending a training session please DO contact us. Contact information and updated workshop schedules are available on the EdGCM web site: http://www.edgcm.columbia.edu
System Requirements
- Mac OS X 10.3.9 or higher, including Mac OS X 10.4 for PowerPC; Windows 2000/XP, including XP SP2 (Pro Edition recommended)
- Any Mac with a G3, G4, or G5 processor running at 500 MHz or faster; Any PC with an Intel or AMD processor running at 300 MHz or faster
- 1 GB of free disk space (for installation only; simulation results may require as much as an additional 10-15 GB)
- 128 MB of RAM, 256 MB recommended
- Internet connection is helpful but not required
Installation Guide: Mac and Windows
For Mac OS X
- Insert the installation CD, or download the latest version from the website
- Double-click on the installer icon. Please note that you must type in an administrator’s password to complete the installation; if you do not have one, you will need to ask your IT administrator for assistance.
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- Follow the on-screen instructions. The installation will plce an EdGCM folder on your desktop, and an EdGCM icon in the Dock. EdGCM will launch automatically once installation is complete.
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Note on cross-platform compatibility
All output files produced by the Mac OS X version of EdGCM 3.0 are compatible for use with the Windows 2000/XP version, with the exception of files used by SuSpect, as this program currently has no Windows equivalent.
For Windows 2000/XP
- Insert the installation disk, or download the latest version from the EdGCM web site.
- Double-click on the EdGCM_PC_Installer. Please note that you may need an administrator’s password to complete the installation; if you do, you will need to ask your IT administrator for assistance.
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- Select the components of the EdGCM package that you wish to install. we recommend that you leave all choices checked since QuickTime and Java are required to use EdGCM. The QuickTime installer will only run if you do not already have QuickTime installed. The Java installer will replace any existing copy of Java with the latest version from Sun.
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- If you do not already have QuickTime and Java on your PC, installation of these components will begin now. Simply accept the license agreements and opt for a typical setup rather than a custom installation. The installation process for these programs may take several minutes each.
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- Launch EdGCM from either the Start Menu or from the shortcut on your desktop.
Note on cross-platform compatibility
All output files produced by the Windows version of EdGCM are compatible for use with the Mac version
Some Notes Before You Begin
Performance: How Fast Will It Run?
The speed at which the GISS GCM runs is based primarily upon the speed of the computer’s CPU. Other factors that play a role include the number of applications running at the same time, compiler optimizations, and whether or not your system is dual- or single-processor. The 64-bit CPUs in machines such as the PowerMac G5 allow the GCM to run significantly faster, since twice as many calculations are possible during one clock cycle than in the typical 32-bit systems used by most desktop computers.
The GISS GCM divides the atmosphere into a three-dimensional grid system. The version incorporated into EdGCM uses an 8° X 10° latitude by longitude grid system, and has nine vertical layers in the atmosphere and two ground layers. Running the climate model entails the solving of a series of complex physics equations for every cell in the grid, and a single simulated year involves many billions of calculations. Real-world performance has always been essential for the GISS GCM for research purposes, so the model was originally coded to be highly efficient. It has been further optimized to run at acceptable speeds on desktop computers without sacrificing any accuracy, but newer desktop computers will run the model the fastest.
Over the past four years, the number of simulated years per day (syears/day) for the GCM has increased more than twenty-fold on desktop Macs. An original iMac 233MHz computer could finish a 5-year simulation in about one day, while a PowerMac dual-G5, running at 2GHz, can complete two 120-year simulations in the same amount of time. As a general guideline, most simulations that would be of interest (either in the classroom or for research) need to run at least 10 simulated years. Simulations with altered forcings, such as increased greenhouse gases, must run using the predicted ocean option and require a minimum of 35 simulated years to reach equilibrium.
Table of simulated model years per day. The speed at which the GISS GCM runs on a desktop computer scales closely with CPU speed. However, changes to the microchip architecture and the optimizations used at the time of compiling may also have a significant impact. The 64-bit G5 processors in particular are significantly faster per CPU clock cycle than older processors. Although we do not have Windows PC benchmarks at this time, we expect PCs to scale with MHz in a fashion similar to the G4 processors.
| Computer (CPU) | CPU Speed | Simulated Years / Day |
| iMac (G3) | 233 MHz | ~10 |
| eMac (G4) | 800 MHz | ~35 |
| PowerMac (dual-G4) | 533 MHz | 31.2 |
| PowerMac (dual-G4) | 1.42 GHz | 66.1 |
| PowerMac (dual-G5) | 2.0 GHz | 120-200* |
| Dell OptiPlex (P4) | 2.8 GHz | 130 |
*Dependant upon compiler optimizations.
It is also important that you not let the computer “sleep” when the GCM is running. Sleep mode will cause the run to stop and can corrupt the files required to complete the simulation. To prevent the computer from going into sleep mode, the Energy Saver settings for your Mac (Figure 1-7) should be set to “never sleep the computer.” (Setting the display to sleep is fine, and will not effect your simulations). In addition, do not check the box that allows the hard disk to sleep, as this may also damage simulation output files.
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For PCs, the appropriate power settings are set through the Control Panel (Figure 1-8). In the Control Panel, double-click on “Power Options” to bring up a dialog box to display Power Option Properties (Figure 1-9). Select the Power Schemes tab, and from the drop down menu select the “Always On”option. As with Macs, allowing the monitor to go to sleep will not affect the running of the GCM.
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Under both Mac OS X and Windows 2000/XP you may run additional applications, such as Microsoft Word or Excel, while the GCM is running. You may even start more than one simulation at a time, although the simulations will then have to share processor time. On single-processor systems any additional applications will slow the GCM dramatically, but will not harm the simulation in any way. On dual-processor computers the impact on the speed of the run will be minimal unless you run many applications at once. Finally, you can quit the EdGCM 4D interface once a simulation is running, because the GCM runs as a separate application in the background. However, you will need to restart the EdGCM 4D interface and choose a currently running simulation if you want to pause the simulation, or to analyze the output once the run has finished.
QuickTime Video Tutorials
Note: The video tutorials for version 3.0 are being redone to reflect the significant interface changes made in this release. Please watch our web site (www.edgcm.columbia.edu) for news on the availability of the new video tutorials.
EdGCM on Your Hard Disk
There are four main components to the EdGCM software suite: the EdGCM 4D folder hierarchy, which provised the organizational framework for the suite; the 4th Dimension® database, which provides the structure for the EdGCM 4D interface and database, and integrates the two; the GISS GCM Model II, the GCM at the heart of this software package; and the visualization software - EVA, SuSpect, and Panoply - that permit the simulation data to be displayed and more easily understood.
The EdGCM 4D Folder Heirarchy
EdGCM incorporates a large folder hierarchy to integrate the graphical user interface with the GCM, the database, the visualization programs, and a host of other utility programs. This hierarchical structure is absolutely necessary to the proper function of EdGCM and its components, so users should not rename, delete, or move any of the folders within the EdGCM 4D folder. However, the EdGCM 4D folder itself can be moved as long as no programs are running and the internal organization of the folder is not altered.
The Applications folder contains all the Fortran programs to analyze output and many other support files. It also contains copies of parts of the EdGCM Suite, but may not contain the most up-to-date versions. Users should not change the contents of this folder unless specifically informed to do so by an update message.
The Database folder contains the EdGCM interface and ALL of the information about the simulations. Never replace the contents of this folder with those from another computer since this will overwrite all of your simulations''' Similarly, if you delete this file you will lose all information about your simulations.
The Data folder contains tables of greenhouse gas (GHG) concentrations (measured and projected) for 1850-2050, and values for the solar constant for 1500-1998. There is also a link to additional datasets for a variety of observations available from the GISS web site (http://data.giss.nasa.gov).
The Docs folder contains several important documents, most in Adobe Acrobat format, including: 1) this installation guide; 2) the paper describing the GISS GCM Model II (Hansen et al., 1983 first appeared in the American Meteorological Society’s Monthly Weather Review journal); 3) the original proposal to the National Science Foundation that funded EdGCM; and 4) an EdGCM presentation poster from the Geological Society of America’s 2003 annual meeting in Seattle.
The eJournals folder contains any eJournals that have been exported for use on the web via the “eJournal to web” command in EdGCM (see the toolbar when the eJournal window is open). The individual folders contained inside the eJournal folder can be copied to any website or e-mailed to us if you wish to have them considered for publication on the EdGCM website.
The Images folder contains any images you wish to make available through EdGCM’s Image Browser utility. If folders containing images are removed or added to the Images folder, it is necessary to click on the “Update” button inside EdGCM (see the toolbar when the Image Browser is open). The Image Browser will accept any images that are stored in a QuickTime compatible format. This does NOT, however, include images in the “gif” format.
The Input, Input Oceans and Input Forcings folders contain boundary conditions and initial condition files that are used by the GISS GCM. Since these files are necessary for initializing runs, deleting files from either of these folders is not recommended because it may destroy your ability to set up and run simulations. Adding files to these folders, while not damaging to simulations, will cause clutter in various menus within the EdGCM interface. It is best to add files to these folders only when instructed to do by an update message.
The Multimedia folder will contain a series of tutorial QuickTime videos about using EdGCM’s features, once updated videos are complete. Check http://www.edgcm.columbia.edu for news on updated video availability.
The Output folder contains output from any simulations that have been run using EdGCM. Each time a new simulation is started, a “run folder” is created inside the Output folder. Run folders are named after the “run ID” in the Setup Simulation window. Any run folder is basically a stand-alone simulation that could theoretically be moved, intact, to another computer and started. However, we recommend that you leave the run folders within the EdGCM folder so that you may use EdGCM’s analysis and visualization programs to post-process and view the output.
The 4th Dimension Database
4th Dimension® is the tie that binds the EdGCM 4D graphical user interface together with the databases generated by simulations. A powerful relational database that runs on both Mac and Windows platforms, 4th Dimension® organizes the huge quantity of output generated so that users can focus upon analyzing the results of their simulations rather than having to search for the information of interest.
The GISS GCM Model II
The heart of EdGCM is the GISS GCM Model II (described in detail in Hansen et al. [1983]), a three-dimensional model which solves numerically the physical conservation equations for energy, mass, momentum and moisture, as well as the equation of state. GISS Model II has a horizontal resolution of 8̊ latitude by 10̊ longitude, nine layers in the atmosphere extending to 10 mb, and two ground hydrology layers. The model accounts for both seasonal and diurnal solar cycles in its temperature calculations. Cloud particles, aerosols, and radiatively important gases (e.g., carbon dioxide, methane, nitrous oxides) are explicitly incorporated into the radiation scheme. Large- scale and convective cloud cover are predicted, and precipitation is generated whenever supersaturated conditions occur. Snow depth is based on a balance between snowfall, melting and sublimation. Sea surface temperatures (SSTs) are calculated using model-derived surface energy fluxes and specified ocean heat convergences. The ocean heat convergences vary both seasonally and regionally, but are otherwise fixed. This is the primary mixed-layer ocean model developed for use with the GISS GCM (described in detail in Russell et al. [1985] and in appendix A of Hansen et al. [1988]).
Certain boundary conditions necessary for simulations (e.g., levels of various atmospheric gases, solar luminosity) can easily be adjusted for customized simulations. Other boundary conditions, generally those that are geography- dependent (e.g., alternate land mass distributions for paleoclimate simulations; topography; vegetation) are not customizable for the purposes of most EdGCM users. Development of geography-dependent boundary conditions is a highly labor-intensive task, so new alternatives are not likely to be released in the short term. However, if EdGCM users express a strong interest in a particular paleoclimate or future climate scenario that requires a set of alternative boundary conditions, we will make an effort to incorporate that scenario in a future release.
Visualization Programs
''EVA'' (EdGCM Visualization Application) is a mapping tool that allows users to plot latitude-longitude and vertical gridded data contained within datasets in the popular netCDF format (generated in this case by EdGCM in the course of data processing). The user may select from a large menu of global map projections and slice specific latitude-longitude arrays from larger multidimensional arrays, which might also have dimensions in altitude or time. EVA was written using the powerful IDL language for scientific visualizaton, and REALBasic. It will run in both Mac (OS X 10.3.2 and higher) and Windows (98, 2000 and XP) environments.
SuSpect is a Mac-only data viewer designed for searching and exploring large text-formatted data sets. It was specifically designed for viewing the standard climate diagnostic tables generated by the GISS GCM and includes the ability to interpret IBM line printer control characters (e.g., page feeds, overstrikes, etc.). It gives the user an efficient means of comparing data tables that reside within one text file, but its real power lies in its capabilities for comparing multiple data files.
Additional Utilities
Panoply is another mapping tool that allows users to plot latitude-longitude and vertical gridded data contained within datasets in netCDF format. Since Panoply is as Java application, it will run in both Mac and Windows environments. Panoply is best used for large datasets, or with generic netCDF files created by programs other than EdGCM.
Panoply is now being developed separately from the EdGCM Project. For additional information and updates, please go to http://www.giss.nasa.gov/tools/panoply/
Several additional Mac-only utilities have also been included within the EdGCM suite. The function of these utilties is largely transparent to the user, although some may find the features of MapProjector and Colorbar Tender useful even beyond the needs of EdGCM data visualization.
MapProjector converts 2-D map images into 3-D global views. MapProjector creates three publication-quality projections: Mollweide, stereographic, and orthographic. It also supports vector overlays and high quality PostScript printing.
Colorbar Tender allows the user to create and edit scientific color tables similar to those used on The Weather ChannelTM. Colorbar Tender supports the color table formats used by many popular programs including: PAL, HDF, and AppleWorks Palette. AppleWorks®, IDL®, Transform, NOeSYS®, and Panoply have been tested with color tables created in Colorbar Tender.
FileInfo changes the creator (owner) of a file, the type file, and attributes of files or folders (e.g., whether the file extension is displayed, a file or folder is locked).
Known Software Problems and Issues
- We recommend that you NOT leave the GCM running on a Windows laptop unattended. We have found that some Pentium laptops have difficulty dissipating heat and may shutdown (hibernate) without warning causing the climate model to crash. This does not appear to harm the laptop, but can corrupt GCM output files.
- Mac OS X warns you about opening the EdGCM Helper Applications the first time they are used. You should allow the helper applications to open or you will not be able to see the files they want to display. To read more about why Mac OS X displays this warning, see the web page, About Security Update 2004-06-07 (http://docs.info.apple.com/article.html?artnum=25785).
- EdGCM will work as described on MacOS X using the default HFS+ disk format. We do not recommend using EdGCM on UFS or case sensitive HFS formatted disks as some bugs may appear.
- A few PCs have exhibited strange behavior when running long simulations. The behavior has been traced to faulty cooling of CPUs and replacing the computer has fixed the problem. Macs appear to have sufficient cooling to avoid similar problems with long simulations.
- EdGCM has not been fully tested on MacOS X for Intel, and is not officially supported in this beta.
See http://forums.edgcm.columbia.edu/faq.php
EdGCM Version History
3.0 (in progress)
Bug Fixes
Enhancements
Tasks
2.5 (2005-10-20)
2.4.2 (2005-10-20)
