Software Engineering

The ROC Software Engineering (ROC/SWE) section provides a variety of support for users of the WSR-88D system. The principle support includes the development, maintenance, enhancement, and problem analysis of software for WSR-88D operational systems. Software Engineers are continuously implementing and testing software modifications that have been requested by NEXRAD users through their respective agencies: the Department of Defense, the Department of Transportation, and the Department of Commerce. Software Engineering also corrects software defects affecting field operations, and applies security Operating System Updates to maintain our authorization to operate.

Software Engineering's workload is primarily divided between the components of the NEXRAD WSR-88D: the Radar Data Acquisition (RDA), the Radar Products Generator (RPG) and the Master System Control Function (MSCF). The MSCF hosts operator user interfaces to the RDA and RPG, providing command, control and status monitoring for the WSR-88D system.

Software Engineering maintains the Archive Level 2 monitoring and radar data distribution software, also known as National Level 2 (NL2). The NL2 project is responsible for ensuring valuable WSR-88D radar data is reliably distributed to the Level 2 user community in real-time. Software Engineering also maintains a Level 2 status page showing Level 2 statistics including radar status, operating mode, and data distribution latency values for all WSR-88D and TDWR/SPG network sites (see https://www.weather.gov/nl2/).

Software Engineering maintains the Special Product Generator (SPG) software which supplements the NEXRAD WSR-88D product set with products produced from the FAA TDWR base data.

Software Engineering assists with GIS-related projects such as wind farm proposal analyses and radar coverage maps, and blockage data. These help determine impacts to a radar and assist with radar move and low elevation angle studies.

News & Information - Current Software Engineering Activities:

• RDA/RPG Build 24.0:
  • Build 24.0 includes several enhancements to the 2D Velocity Dealiasing Algorithm (2DVDA): 2DVDA's internal VAD creates a background wind field that is not always representative along discontinuities such as fronts, the leading edge of a QLCS, etc. This can cause velocity dealiasing errors if the algorithm tries to "correct" a solution against the non-representative background wind field, and 2) Turbulence, especially related to high vertical wind shear, can cause dealiasing errors. Reliably detecting turbulence would allow 2DVDA to apply specific dealiasing techniques to handle it, improving overall dealiasing quality.
  • Build 24.0 implements Azimuthal Shear (AzShear) on the RPG (non-operational). Originally intended as an interim product for the New Mesocyclone Detection Algorithm and New Tornado Detection Algorithm (currently in development by NSSL), AzShear went before forecasters as a standalone product during NSSL's Hazardous Weather Testbed. Forecasters appreciated standalone AzShear's utility to expand situational awareness during warning decision-making, and so now the ROC is working with NSSL to incorporate AzShear on the RPG.
  • Build 24.0 adds Long-Term Average Reflectivity (LTAR) input to Hydro Classification Algorithm. The LTAR algorithm and product were added to the RPG in Build 21.0 non-operationally. Data retention and efficiency improvements were added in Builds 22.0 and 23.0. LTAR is effective in identifying areas of persistent ground clutter, and particularly wind farms. build 24 adds LTAR input to the Hydrometeor Classification Algorithm to eliminate erroneous classifications that are often associated with ground clutter. It includes logic that helps retain valid meteorological classifications from stronger echoes, even in the presence of persistent ground clutter.
  • Build 24.0 updates QZdrCal algorithm with cold season modification. The QZdrCal algorithm that estimates ZDR bias from dry aggregate snow was added for evaluation purposes in Build 23.0. That version of the algorithm was designed for the warm season and therefore required the detection of an elevated melting layer. NSSL has developed a cold season version of QZdrCal that does not have the melting layer requirement. This effectively makes QZdrCal an all-season algorithm. Evaluation of its performance for eventual replacement of the legacy dry snow ZDR bias estimator is ongoing.
  • A new tool will be added to RDA Build 24.0 to display the antenna motion as a function of both elevation and azimuth, similar to an existing tool used by the WSR-88D Hotline. This will greatly help the field when the Hotline is working with site technicians in tracking down hardware and pedestal calibrations issues.
  • In Build 24.0, QPE will be smoothed to remove discontinuities. This change focuses on the discontinuity that occurs between rain rate estimators R(A) and R(Z) or R(Z,ZDR). When the Specific Attenuation estimator R(A) is active it can produce rainfall rates that are different from ones used within and above the melting layer. This can cause a sharp boundary in the resulting Quantitative Precipitation Estimate accumulations. A 15 km wide area of weighted mean smoothing is applied between R(A) and R(Z) that blurs out this sharp discontinuity making the QPE accumulations appear more "natural".
  • A fix for a problem with SZ-2 velocities is being implemented in RDA Build 24.0. The update addresses a situation where weather with high reflectivity values did not have corresponding velocities or spectrum widths.
  • In RPG Build 24.0, Configuration Presets are being implemented, which allow users to specify VCP, # SAILS cuts, # MRLE cuts, # MPDA elevation, Velocity Measure Increment, and Base Tilt On/Off with a single selection instead of requiring making these selections individually. There will be 5 pre-defined and uneditable Presets, the RPG operator can add up to 5 user-defined Presets.
  • In RDA Build 24.0 a fix to the RDA will allow the RPG to gain control of the RDA even when it is under RMS control.
  • Build 24.0 will include several RPG HCI GUIs ported from X/Motif to GTK+. The functionality will be preserved. The look and feel will be slightly different.
  • Build 24.0 is currently being deployed.
• RDA/RPG Build 24.1:
  • Build 24.1 contains OS security patches, an increase in the number of products to a maximum of 800 on a Routine Product Set (RPS) list for Class 98 users, and a lower elevation angle of 0.3 deg for Boston, MA (KBOX).
• RDA/RPG Build 25.0:
  • RDA/RPG Build 25 includes several major changes. One of the biggest changes is moving RPG to the shelter, co-located with the RDA. Also NWS Redundant systems will have fully redundant channels,i.e., each channel will have its own RPG. Essentially FAA Redundant and NWS Redundant will be indistinguishable from each other.
  • In Build 25, RPG site-specific data and the RDA HCI Jar files will be included on the load media and installed with the OS and application software. There will no longer be separate RPG site-specific and RDA HCI Jar media provided to the site.
  • Support for the Multiple, Repeat Low-Elevation (MRLE) is being added to the “Add MPDA” option. A user will be able to enable “Add MPDA” when MRLE is active, or vice versa.
  • All VCP options will be consolidated into a new VCP and Mode Control GUI at the RPG. This should make it easier for users to view current VCP status and change VCP options as there will no longer be separate RPG HCI GUIs for setting things like SAILs, MRLE and Add MPDA.
  • In Build 25, VCP Presents, which were added in Build 24, can be associated with a weather mode default just like a VCP has always been able to be associated with a weather mode default.
  • Build 25 adds the following new products:
    • Long-Term Average Reflectivity, LTR, product ID 188, 256 data levels, 1 degree radials, 230 km range. This product represents the average reflectivity over a 30-day period at 0.5 degrees elevation angle. It provides a visual representation of persistent ground clutter and is used by the Hydrometeor Classification Algorithm to label persistent ground clutter. The product is generated once per hour but its contents update only once per day at 00Z.
    • Surface Hydrometeor Classification, SHC, product ID 203, 19 data levels, 1 degree radials, 230 km range. It is a modified version of the Hydrometeor Classification product (HC, 165) at 0.5 degrees. It estimates the hydrometeor classification at ground level using model and terrain height data, based on the 0.5 degree HC product. It is generated once per volume scan at the end of the volume.
    • A new improved resolution Composite Reflectivity, Product ID 95, is being introduced. The product will be polar format, 1 deg x 1x km resolution, 256 data levels, out to 460 km. Users will be able to request this product once support has been added to AWIPS.
    • Azimuthal Shear (or AzShear) shows the strength of velocity gradients across radials of dealiased velocity. It's derived by applying a median filter to the dealiased radial velocity field to calculate the linear least square derivative gradient. AzShear highlights areas of interest that may be harder to spot in the velocity field alone, such as subtle rotations in QLCS or tropical weather situations. Meteorologists participating in the Hazardous Weather Testbed have noted that AzShear increases situational awareness and can enhance confidence in warning decisions. It's important to note that the quality of AzShear's output is intrinsically tied to the quality of the dealiased velocity field - noisy or incorrect dealiased velocity values will cause noisy or spurious shear values in AzShear. However, it's unlikely this would cause undue confusion for a trained user. Once requested, the AzShear product is generated once per elevation scan at a resolution matching that of dealiased velocity. The range of values in the product is -0.1 s^-1 to 0.4 s^-1, at a precision of 0.001 s^-1. Users will be able to request this product once support has been added to AWIPS.
  • The Tornado Detection Algorithm (TDA) performance is being improved. The maximum processing range default is being extended out to 230 km.
  • NL2 client connection status display and Archive II GUI launcher are being added to the RPG HCI. The new display is above the USERS container of the RPG main HCI. Valid status values are CONNECTED (NL2 Client is pulling data from the RPG), DISCONNECTED (there is no NL2 Client pulling data from the RPG) and UNKNOWN (NL2 client status is not being reported).
  • A new RPG Backup Communications Failure Maintenance Mandatory Alarm is being added to the RPG. This alarm will be triggered when Backup Communications is unavailable for use
  • When a user logs into the RDA or RPG, a warning popup occurs to remind users to remove the CAC card from the card reader. Also a popup occurs if a user has been logged in for an extended period of time (over 8 hrs).
  • A new routine for Encoder Alignment is being added to the RDA STS. This will become the new recommended way to determine the alignment of an installed encoder when the antenna is stowed in the associated axis.
  • An application called Remote Software Update (RSU) will be available for a site to download and apply point builds and overlay updates for main WSR-88D devices (RDA, RPG, MSCF, and RCAL). The user requests files to be downloaded from a Remote Update and Monitoring Server (RUMS), hosted at the ROC or Ashburn, to the device. The user then sends the command to apply updates once they have been downloaded. The user can be standing at one device and update another without needing to go to the other device in person (e.g., at MSCF to update the RDA). Updates for RCAL can occur with RUMS, but must be done in person by making a physical connection via a LAN port in the shelter. [Updates via physical media will still be supported.]
  • The RDA will have updated information related to the ports/status for the new power administrator and connection changes related to moving the RPG to the Shelter.
  • The RDA will no longer have the option to generate an offline Bypass Map, so the associated viewer is no longer selectable.
  • For NWS Redundant sites, control of the secondary power panel contactors #1 and #2 will be removed, disabling the power cycling of the transmitter, receiver cabinet and the cabinet cooling fans, and rewiring the cooling cabinet fans directly to the AC terminal strip.
  • RDA/RPG Build 25 is currently in formal System Test.
• NL2 Build 15.0:
  • NL2 Build 15.0 contains security updates, updates to decoders to support Build 24, monitoring of time synchronization at radar sites, removal of all NOAA Profiler Network decoding and display, and new color scheme for VCPs displayed on maps.
  • Build 15.0 was deployed in April 2025.
  • Build 15.1 contains security updateds and bug fixes, as well as the removal of unused client connections.
  • Build 15.1 was deployed in November 2025.
• NL2 Build 16.0:
  • NL2 Build 16.0 contains security updates, necessary network changes to support RDA/RPG Build 25, updates to process for sending data to weather.gov APIs, and updates to web display. Development began in December 2025 and is scheduled to be deployed in April 2026.