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Desktop Weather-Forecast System

Desktop Weather-Forecast System. Jim Kinter, Brian Doty, Eric Altshuler, Mike Fennessy Center for Ocean-Land-Atmosphere Studies Calverton, Maryland USA. Desktop Weather-Forecast System. Opportunity.

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Desktop Weather-Forecast System

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  1. Desktop Weather-Forecast System Jim Kinter, Brian Doty, Eric Altshuler, Mike Fennessy Center for Ocean-Land-Atmosphere Studies Calverton, Maryland USA

  2. Desktop Weather-Forecast System Opportunity • Global weather forecasts are freely available from US National Weather Service (NWS) - data is provided at 1º and 0.5º resolutions • High-resolution (20 km mesh or finer) regional weather forecasts can be produced with mesoscale models, nested in global forecasts Problem • Three barriers to using current operational technology: • Global data sets are very large in volume and granularity • Large communications bandwidth is required to obtain them • Data assimilation and global numerical weather prediction (NWP) models are very large calculations • Supercomputers are required to run them • Experts in NWP and supercomputing run global and regional models • Cadre of NWP and supercomputer experts must be trained

  3. Desktop Weather-Forecast System Proposed Solution • Desktop Weather-Forecast System (DWS) Combines • Distributed data access and analysis technology (GrADS Data Server) • US NWS regional weather prediction model (workstation Eta)

  4. NCEP Global Weather Forecasts Desktop Weather-Forecast System NWS COLA Global Weather Forecasts GrADS Data Server Region-Specific ICs & Lateral BCs WWW Regional NWP Model

  5. Desktop Weather-Forecast System Enables real-time weather forecasts through: • Easy access to real-time initial and boundary conditions data • Easy configuration of regional NWP model for any locality in the world • Readily available, low-cost personal computing hardware/software • Moderate speed Internet connection

  6. Desktop Weather-Forecast System • Advantages: • Runs on low-cost computers such as PCs (Linux); also runs on UNIX workstations; capable of utilizing multiple processors via MPI • Includes easy to use scripts for selecting domain, running a forecast and displaying model output • Provides a unique capability to: • View local or regional weather observations • Create locally-relevant custom displays • Make a regional weather forecast • Graphically merge local weather observations and analysis/forecast products

  7. Desktop Weather-Forecast System Ease of use: • Point and click interface to set up region the first time • Automated access to US NWS global NWP model output for • Atmospheric initial conditions • Initial soil wetness, snow depth • Surface boundary conditions (sea surface temperature, sea ice) and lateral boundary conditions (atmospheric circulation) • Automated linkage to powerful desktop display program (GrADS) to visualize results of forecast • Full documentation for getting data, running forecast

  8. Computer specifications and features • Dell Precision Workstation 470n • Dual Intel Xeon processors, 3.40GHz, 2MB L2 cache per processor • 6GB total memory • 500GB total disk space • Red Hat Enterprise Linux ES 4 • Intel Fortran Compiler 9.0 for Linux • Intel MPI Library 2.0

  9. DWS Installation: Preliminary steps • README – brief instructions for setting up and running DWS. Read this first! • topo – directory containing global 30” topography data • wseta.tar.Z – DWS package (compressed tar file)

  10. DWS Installation: Preliminary steps • Uncompress and untar wseta.tar.Z • After untarring, remove wseta.tar • Change to “topo” directory • Identify the set of compressed tar files that is sufficient to cover your domain of interest. The files are named using a convention that is described on the next slide. • Copy this set of files to ../worketa_all/eta/static/topo and change to this directory • Uncompress and untar all of the .tar.Z files • After untarring, remove the tar files to save disk space • The files named U* contain the raw 30” topography data • For the whole world, the uncompressed topo data requires about 1.8 GB of disk space; if disk space is not an issue, just copy all of the .tar.Z files rather than trying to figure out which ones you need to cover your domain

  11. DWS Installation: Preliminary steps • The compressed tar files containing topography data are named as follows: • The first three characters of the file name identify the latitude of the southern boundary of the sector (each sector covers 60 deg longitude by 30 deg latitude) • The fifth character of the file name (a number from 1 to 6) indicates the sector’s longitudinal position • Example: 30S_2.tar.Z contains data covering 30S-00N and 120W-60W (Peru is located in this sector) • An image file showing a world map with sector boundaries overlaid (rev_topo_plot_crop.gif) is provided in the directory containing the compressed topography data • The next slide graphically illustrates this file naming scheme

  12. Areal coverage and naming of topography data files 1 2 3 4 5 6 90N 60N 30N 0 30S 60S 90S 180 120W 60W 0 60E 120E 180

  13. DWS Installation: Preliminary steps • There are a few additional settings in the “build” and “runeta” scripts, and elsewhere, which may need to be changed under certain circumstances. These will be covered later when the scripts are discussed in detail.

  14. DWS files and directories: Important top-level files and directories Top-level directory Main DWS build script Eta model codes and scripts Code to interpolate model output to a different horizontal grid Libraries used by various codes Directory for storing initial and lateral boundary input data Post-processor Documentation directory Intermediate post-processing code Data acquisition and pre-processing codes and scripts Main DWS run script

  15. DWS files and directories: two important scripts • Top-level directory is “worketa_all” • “build” script sets model configuration (domain, resolution, etc.) and compiles the model codes • “runeta” script sets run-time variables (date, forecast length, etc.) and runs the model

  16. DWS Documentation • README – brief instructions for setting up and running DWS. Read this first! • worketanh_nwsoil.pdf, worketanh_nwsoil.ps – Original documentation for the workstation Eta model, written by Matt Pyle of NCEP (2002)

  17. The “eta” directory: Important subdirectories • bin – contains fixed-field data and pre-processor scripts • exe – contains compiled executables • install – contains scripts that are called by the main build script during the compilation process

  18. The “eta” directory: Important subdirectories • runs – the model and post-processor run in this directory; contains all necessary pre-processed input data, as well as model output data after a run is finished • src – contains model source codes

  19. The “eta” directory: Important subdirectories • static – contains a subdirectory “topo” where 30” topography data is stored • util – contains scripts and codes that implement the DWS graphical user interface (GUI) and perform other miscellaneous tasks

  20. The DWS Graphical User Interface (GUI) • The DWS GUI consists of three parts • The first part is invoked by the “build” script and enables the user to specify the model domain, resolution and several other parameters using a simple point-and-click interface • The second part is invoked by the “runeta” script and enables the user to specify several run-time variables, such as the date, forecast length and cumulus convection parameterization • The third part is invoked directly from GrADS and enables the user to view 13 different model output fields, for all available vertical levels and forecast times. It is also capable of animation, zooming, and saving plots to a file. • All three parts of the DWS GUI are optional; the user may choose to disable the GUI in the “build” and/or “runeta” scripts, and instead specify the model parameters directly in the scripts. This is useful for more experienced users and for those who wish to run DWS in batch mode (e.g. in a cron job).

  21. The DWS GUI, Part I: Domain selection and resolution specification • Execute the “build” script to begin the process of configuring and compiling DWS for your domain • For a given domain and resolution, this script only needs to be run once • After the user has completed all the steps in the GUI, control returns to the “build” script and the codes are then compiled • The next 12 slides give a step-by-step demonstration of how the GUI (Part I) works

  22. Based on the location of your domain of interest, choose whether the world map is centered on Greenwich or the International Date Line

  23. We have chosen a world map centered on 0 degrees (Greenwich)

  24. We have not selected the actual domain yet; we have just zoomed in on the overall region of interest. From this screen, the approximate domain is chosen.

  25. Choose 1.0 deg – the 0.5 deg data is not currently available, though it may be in the future

  26. This is the exact domain boundary – note that the sides are curved and therefore they do not have constant latitude or longitude

  27. If you wish to start over again and select a different domain, click “No”

  28. Always choose “Eta” for DWS applications

  29. NCEP recommends using 25 hPa

  30. Always choose “GFS from GDS”. The other option exists only for specialized applications.

  31. This screen summarizes your choices. At this point, the GUI is finished and after you click on “Continue” the model will be compiled.

  32. The DWS GUI, Part II: Running the model • Execute the “runeta” script to start a DWS forecast or historical simulation • After the user has completed all the steps in the GUI, control returns to the “runeta” script • The “runeta” script then fetches initial and lateral boundary data and runs the pre-processor, forecast model, and post-processor • The next 13 slides give a step-by-step demonstration of how the GUI (Part II) works

  33. In this demonstration, we have chosen to run a historical simulation

  34. Screens for specifying the initial date do not appear in the case of a real-time forecast

  35. In this demonstration, we have chosen the initialization date to be 13 March 2006. The year must be between 1901 and 2099.

  36. Select 00 UTC or 12 UTC – although GFS is run operationally 4 times per day, the COLA GDS only has data from the 00 and 12 UTC runs

  37. Choose 6 h – this is the interval at which GFS forecast data is available on the COLA GDS

  38. Choose “lat-lon” – the GUI for viewing DWS output requires the data to be on a lat-lon grid

  39. Select “Hydrostatic” – nonhydrostatic dynamics is an experimental feature

  40. This screen summarizes your choices. At this point, the GUI is finished and after you click on “Continue” the model run will start.

  41. The DWS GUI, Part III: Visualizing model output • After a DWS run has finished: • Go to the worketa_all/eta/util directory • Start the data visualization program GrADS by entering the command “gradsc” • At the GrADS prompt, run the DWS output visualization GUI (a GrADS script) by entering the command “view_gui” • As the user performs different tasks with the GUI, useful status information is displayed in the GrADS command window • The next 18 slides give a step-by-step demonstration of how the GUI (Part III) works

  42. The screen looks like this before any fields have been displayed

  43. Click on “Field” to access a drop-menu showing the 13 available fields, then click on the field you wish to display

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