UCAR | NCAR | CISL | IMAGe DAReS DART Publications Presentations Data
Contact Us | Visit Us | People Search	advanced

General DAReS Home DAReS People Overview Research DART -- Jamaica 12Apr2007 DART -- Pre_J 02Oct2006 CAM-DART Publications, Reports Resources DART Developer page Ensemble Filtering Tutorial 19Jan2005 Historical Panel Meeting 24Sept2004

The Data Assimilation Research Testbed -- DART The 500hPa geopotential height from 20 ensemble members of an 80 member experiment with a T85 resolution of CAM (00Z 01 Feb 2003). The contour sets are from 5320 to 5800 by 80.

Welcome to the home page for the Data Assimilation Research Testbed (DART).

If you are using DART: you need to know about recent (2Jun2008) changes.

Overview Topics

• Here is some introductory material on the general concepts of Data Assimilation.
• You can explore the example models and observations which are included with the DART software distribution.
• You have an existing model and/or data observations and would like to experiment with assimilating them with the DART software.
• You are a current DART user and want to download the latest updates.
• You are interested in using the DART software and tutorial materials to teach a class using Data Assimilation (or would like to use the DART tutorial material to teach yourself).
• You are interested in learning how DART runs on parallel machines.
• You want to contact our group for more information.

Getting Started

The DART software provides a flexible, extensible framework for conducting data assimilation research on a wide variety of models and observations. In order to facilitate the incorporation of new models (which, in the Atmospheric Science community are generally written in F90), the DART software is written primarily in F90. The noteable exceptions are the shell scripts that control execution and the Matlab® diagnostic scripts.

The DART system comes with many models - ranging from 1-dimensional Lorenz systems to the dynamical core of a full atmospheric model. DART also has an extensive tutorial that explains typical DART experiments and explores many aspects of ensemble data assimilation. The tutorial is an entire directory in the DART software distribution, so it can be browsed (it is a series of .pdf files) Download the DART source code and follow the instructions on the web page for the current release for instructions on how to build an executable, run the "workshop" experiments, and look at the results.

DART requirements

DART is intended to be highly portable but has a strong Unix/Linux preference. DART has been run successfully on Windows machines under the cygwin environment. Those instructions are under development - if you would like to be a friendly beta-tester please send me (Tim Hoar) an email and I'll send you the instructions, as long as you promise to provide feedback (good or bad!) so I can improve them. My email is   thoar @ ucar . edu - minus the spaces, naturally. Minimally, you will need a Fortran90 compiler and the netCDF libraries built with the F90 interface. History has shown that it is a very good idea to make sure your run-time environment has the following:

DART tested platforms/models/compilers

DART is intended to be highly portable - and has even run successfully on Windows machines running the cygwin environment. Those instructions are under development and so are not included in the following table. The most current version of DART (Jamaica) has been tested on the following:

DART code distributions

DART is distributed primarily through an anonymous-access readonly Subversion (SVN) repository. This makes updates and comparisons between your sandbox and the latest, greatest version of the code trivially easy. The same cannot be said with a TAR file. If you are not familiar with SVN (the client application of subversion), you should take a stroll through my svn primer If you cannot (i.e. are firewalled out) use svn, please let me know and I'll send you a tarfile ... as a last resort.

Since the DART software is still an area of active research, there are multiple distributions, with more on the way. We'd like to be able to contact people to inform them of any bugs or updates. (This includes local users, BTW!) As you can see by the timetable of distributions, you could expect to get about 2 more emails per year, so PLEASE use a real email address when signing up. I solemnly swear to protect your email address like it is my own!

download instructions for the latest releases.

The Jamaica version of DART (the latest 'official' release) has the following attributes for this file. Since svn uses 'mixed revisions', files in the distribution will have different revision numbers. If you download the 'trunk' (the latest version) - the revision numbers are assuredly different.

User-Visible changes to the TRUNK (circa 2 Jun 2008)

Some ideas are just too good to postpone till the next major release. The following changes to the DART trunk code may require you to take additional action after an update:

1. Additional function added to the preprocess program also means that you now only need to have obs_def_mod.f90 in your path_names_* files and it will include the code for all other obs_def_* modules automatically. If you have additional obs_def lines for gps, altimeter, or other specialized obs_def files, they must be removed or you will get an error similar to this:
   AMBIGUOUS: Module obs_def_gps_mod is associated with ../../../obs_def/obs_def_gps_mod.f90 as well as ../../../obs_def/obs_def_mod.f90.
   Adding and removing various obs_def files now only involves changing the &preprocess_nml:input_files namelist item in the input.nml file. We will update all path_names_* files in the DART subversion (svn) repository; this only applies to files you have that are not under svn control.


2. All model work directories now have a quickbuild.csh script instead of workshop_setup.csh. The workshop script still exists in some model directories, but may change in upcoming releases to accomodate DART tutorial workshops. The quickbuild script recompiles all the programs; it does not try to run any of them. By default it builds all small models without MPI, and builds the large models (CAM, WRF, AM2) with MPI. It takes -mpi and -nompi arguments.


3. The MPI version of filter would sometimes not kill the entire job if one task failed. This resulted in jobs hanging and using up computing resources unnecessarily. We added a new routine to the utilities_mod.f90 called exit_all(). For MPI-enabled jobs it calls MPI_Abort() to inform all other tasks that one has failed. This should cause an MPI job to exit immediately on error. Nothing new happens for programs which do not use MPI. However, this change requires adding the mpi_utilities/null_mpi_utilities_mod.f90 file to many of the path_names_* files where it was not required before. It might also require adding time_manager/time_manager.f90 if it is not already there. We will update all path_names_* files in the DART subversion repository, but you may have programs of your own that use utilities_mod routines - in which case your programs will now need to link with null_mpi_utilities_mod. Without it, the error you see will be similar to this:
   /usr/bin/ld: Undefined symbols:
   _exit_all_


4. The default mpi interface utility code should now compile as-is for every supported compiler except gfortran. (You should no longer need to go into the code and edit the interface block for the system function.) If you are using the gfortran compiler, in the $DART/mpi_utilities directory you will find a script called fixsystem that you can run to make the file compile without having to edit it by hand.

DART Tutorial Materials and Presentations

The DART system comes with an extensive set of tutorial materials, working models of several different levels of complexity, and data to be assimilated. It has been used in several multi-day workshops and can be used as the basis to teach a section on Data Assimilation. Download the DART software distribution and look in the tutorial subdirectory for the pdf and framemaker source for each of the 22 tutorial sections.

Browsing the tutorial directory in the distribution is worth the effort. Taking the tutorial is FAR better!

Presentations about DART:

The FULL list of presentations (as well as some of the presentations themselves) and publications is available on our Publications page. A short list of presentations, posters, and seminars is offered below:

• The Data Assimilation Research Testbed: Powerful Adpative Fast Assimilation for Geophysical Applications, [presentation .pdf] March 2007
• Assimilation of GPS radio occultation refractivity with WRF using a non-local observation operator. [poster .pdf] Jul 2007
• Data Assimilation for CAM - Research & Development. [poster .pdf] Jun 2007
• Parallel Implementation of Ensemble Filter Algorithms for Data Assimilation. [poster .pdf] May 2007
• Adaptive Spatially-varying Variance Inflation in an Ensemble Filter. [poster .pdf] May 2007
• A tutorial on ensemble filtering, Jan. 2004
• Talk for CAOS Workshop, Dec. 2003
• Overview of Filter DA, AGU, Dec. 2003

Related Links

• FMS group of GFDL
• ESMF -- Earth System Modeling Framework
• UK Met Office Fortran 90 Standards
• WEG -- NCAR's Web Engineering Group
• ncview -- a visual browser for netCDF files

DART Contact list

We're a very small group, so the contact list is pretty short. We don't have a central contact email address, but we all know how to forward email to each other. So no matter who you send the email TO, it will find its way to the best person. Pretty cool, eh?

UCAR : NCAR : CISL : IMAGe : [  DAReS   TNT   GSP   CMG  ]
For problems with the page, contact Tim Hoar - thoar 'at' ucar 'dot' edu

© 2007, UCAR | Privacy Policy | Terms of Use | Contact UCAR | Visit UCAR | Sponsored by

Document: /DAReS/DART/index.shtml
Last modified: Wednesday, 04-Jun-2008 10:33:36 MDT