GEMPAK Status Report

Steve Chiswell
March 29, 2006

Purpose of GEMPAK status report

The activities carried out toward GEMPAK development and support fulfill the following endeavors as described in the Unidata 2008 NSF proposal:

GEMPAK Downloads by Version
  5.6.L 5.6.M 5.7.1 5.7.2 5.7.3 5.7.4 5.8.1 5.8.2a 5.8.3a 5.8.4 5.9.1
Source Code 158 114 171 445 108 393 252 301 317 134 382
Linux Binary 233 260 159 661 395 649 427 529 307 115 411
FreeBSD Binary 29 42 9 23 34 105 8 21 17 4 14
Solaris Sparc Binary 26 23 10 34 19 29 21 14 16 1 20
Solaris x86 Binary 4 10 3 24 2 14 21 7 9 5 16
MAC OSX Binary NA NA NA NA NA NA NA 45 33 5 37


Current Status

GEMPAK Development

NCEP is developing XML/XSLT infrastructure within GEMPAK as part of the creation of products by NMAP2. Future development will include a migration of the current table structure from column based formats to XML, which will remove legacy issues regarding metadata and precision, as well as increase the utility of these tables with other packages.

Internal development has begun on rewriting the core GEMPAK library routines in C. The initial phase is a straight translation of routines from Fortran to C, which will be followed by implementation of dynamic memory allocation, thereby facilitating the use of GEMPAK with increasingly large data sets.

An overarching goal in the GEMPAK library rewrite is to separate the library routines from the underlying data files and formats. This will facilitate the use of GEMPAK routines in the next generation AWIPS development. A primary benefit of this work will be the ability to support a wider range of data sets, including remote access.

GEMPAK 5.9.2 release in progress

The RSL library package used for Level II plotting has been upgraded to version 1.34 which adds several VCPs in addition to changes necessary for new ORDA deployment.

A new program GDCSV has been created to create a comma separated output of data values at grid and lat/lon point locations. This program can be used to output location of maximas found using the HIGH and LOWS functions, as well as all other functions.

Added the ability to display revised NetCDF formats for 2-D and 3-D radar mosaics which will be available from NSSL in the near future.

Capability to save specific cycle time for SPFs has been added to NMAP2 thereby allowing the user to create cycle or model run specific graphics. A new panel has been added to the "Save To SPF File" GUI titled "Save Source Timestamp As:'.

A new program, GDPLOT3, has been added to incorporate the functionality from GPTEXT, GPBOX, GPANOT into GDPLOT2. This program can be used to efficiently create anotated products in a single application.

The plotting of ensemble cyclone tracks in NMAP2 and GPMAP has been enhanced to allow the user to color-code the tracks according to the maximum surface wind in knots at each forecast point.

Three new public library routines have been added to the cgemlib/xml library. These provide some basic query functionality that can be applied generically to xml documents. Additional use of XML use within GEMPAK is being developed for future releases.

GEMPAK 5.9.1 release

New grid diagnostics have been developed to support the new ensemble probability function. These logical functions has been added to provide for multivariate relative frequency (probability) estimations from ensembles. The new ensemble function, ENS_PROB, is provided to perform weighted relative frequency of occurrence calculations. For example, computing the ensemble probability of the wind speed exceeding 10 m/s AND the temperature less than 0 C using equaly weighted ensemble members can be done by:


Modifications were made to the DCMETR decoder to handle changes to the WMO code form effective Nov. 2, 2005: allow "NDV" (no directional variation) to be appended to the 4-digit visibility value; allow "NCD" (no clouds detected) to be used for sky cover for automated systems; allow "COR" immediately preceding the station id to denote a correction.

The number of METAR special reports which can be stored per hour (as text strings) in the GEMPAK file created by DCMETR has been increased from a maximum of 6 to a maximum of 30. Anywhere from 15 specials (at between 81 and 160 characters each) to 30 specials (at less than or equal to 80 characters each) can now be stored for a station for a given hour. The actual number stored depends on the aggregate report length of all the specials for the station at the time. The specials may be viewed with SFLIST (SFPARM=SPCL) or NWX (Observed Data/Surface Hourlies).

A new program, GDGRIB2, is available that converts GEMPAK grids to GRIB edition 2 format. GDGRIB2 converts an existing GEMPAK grid or writes out any grid diagnostic to the GRIB2 file. In addition, a horizontal interpolation is invoked, when necessary, to store the GRIB2 formatted data points on any user specified grid. For information on available parameters and example usage, type "help gdgrib2" in any GEMPAK program.

NTRANS now has the ability to save procedures in NTRANS similar to NMAP2. This functionality allows the user to save settings for models, groups and panel location for multi panel display. A new drop down menu (Procedures) has been added to the NTRANS top menu bar with the options to restore or save a procedure file.

GEMPAK 5.8.4 release

GEMPAK 5.8.4 provides a new directory hierarchy has been employed to facilitate the use/installation of 3rd party libraries which are utilized within GEMPAK. All platform specific files are now maintained and installed under a single tree root facilitation the use of package supplied configure scripts.

The speedpatch modification developed by SUNY-Albany has been rolled in to the Unidata distribution. This modification allows for faster connection between GEMPAK programs and device drivers through use of semaphores instead of previous 1 second sleep intervals. The result is that scripts which generate large numbers of products and overlays can execute much faster.

A new Unidata addition is the NMAP Kiosk program which allows for automated cycling of NMAP loop frames for automated NMAP2 uses. Stored Proceedure Files (SPFs) can be used to configure the loop contents, and the kiosk program will simulate the interactive user selection of loops at specified intervals.

Additional ENS_ ensemble diagnostic functions have been added, including the ability to specify member weights.

GEMPAK application training workshop

The Unidata applications training workshop for GEMPAK was conducted July 25-27, 2005. This year there were 41 registrants for the GEMPAK workshop (space was available for 18 participants; 22 were initially accepted for GEMPAK). The workshops were webcast in real-time. Due to the increased availability and usage of online documents, hardcopies of the GEMPAK manual were not distributed this year for the first time (printing costs were determined to be $85 per manual).

GEMPAK 5.8.3a release

GEMPAK 5.8.3a completes transition of all programs to new grid library routines which allow computations involving grids of different navigations.

GEMPAK gridded data diagnostic functionality has been enhanced to allow for computations over layers containing multiple levels of the vertical coordinate. This functionality allows for a new set of LYR_ functions to be entered in GFUNC or GDPFUN to calculate layer quantities. Additional layer diagnostics will be added in future releases.

Three new ensemble diagnostics have been added in this release. They are:

  1. ENS_SSPRD ( scalar_input_arg ) -- Computes the spread (sample standard deviation) over the members of an ensemble.
  2. ENS_VAVG ( vector_input_arg ) -- Computes the average of a vector over the members of an ensemble. The result is a vector field.
  3. ENS_VSPRD ( vector_input_arg ) -- Computes the spread (sample standard deviation) of a vector over the members of an ensemble.

The XW driver has been modified to allow the user to "take a picture" of the current frame. here is a new GEMPAK command, GSAVE, that takes the output file name as an argument and saves the frame to the file in the GIF format. This command operates from any GEMPAK text-interface program that draws data to an X Window. The export GIF functionality was also added to NMAP2.

The ensemble cyclone tracks generated by various forecast models (GFS, NAM, UKMET, NCEP Ensemble, ...) can now be decoded and displayed (in NMAP2 and GPMAP) as a new miscellaneous data type. In many respects, these data sets are similar to the ATCF forecast track data which is decoded "on the fly" and displayed as miscellaneous data type ATCF in NMAP2 and as parameter ATCF in GPMAP. Ensemble tracks can be found on the NCEP/EMCweb pages.

The objective analysis (OA) programs OABSFC and OABSND have a new parameter OABND. OABND specifies the bounds file(s) to use for 'blocking', that is masking out geographical areas based on bounded areas.

Radar mosaics for GIS

Iowa State is actively using GEMPAK radar mosaics with their mesonet products in GIS applications. To facilitate this process, I developed the GEMPAK program NEX2IMG to generate composite images which can be used with a file to provide GIS navigation information. Daryl Herzmann has put together a How-To document to help other sites set up their own radar mapservers.

Previous developments

  • See September 2005 status report for past information.

    Ongoing Additions

    COMET case studies available via CODIAC

    COMET case studies are compatible with the GEMPAK/NAWIPS environment, and are being made available via the CODIAC system.

    GEMPAK workshop and tutorial online

    All the documentation for the GEMPAK workshop is made available through the GEMPAK tutorial. Included in the presentation are numerous sample exercises and output samples. This format of presentation allows workshop participants to be able to review or utilize any of the material at their home institution. The tutorial is updated as new features dictate.