SR/SSD 98-45

12-1-98

Technical Attachment

John Distefano

NWSO Wilmington, OH

New Algorithms/Products

Tornado Detection Algorithm (TDA) Product:

• No mesocyclone necessary for TDA to be defined.
• Uses Gate-to-gate shear.
• Looks for cyclonic rotation.

Tornadic Vortex Signature (TVS):

• 3-D circulation.
• Base at 0.5º, or below 600m ARL (Above Radar Level).
• Depth 1.5 km.
• Max v 36 m/s (anywhere within circulation), or v 25 m/s at the base level.

• TVS symbol (red, filled, inverted triangle) placed at AZ/RAN of lowest 2D feature.

Elevated Tornadic Vortex Signature (ETVS):

• 3-D circulation.
• Base above 0.5º, and above 600m ARL.
• Depth 1.5 km.
• v 25 m/s at the base of the circulation.

• ETVS symbol (red, open, inverted triangle) placed at AZ/RAN of lowest 2D feature.

TVS Graphic Attribute Table and Alphanumeric Product:

• More operationally useful.
• Includes base, depth, and v information.
• Alphanumeric Product also has max v and height of max v.

Combined Attribute Table (CAT):

• Circulation types will be identified in both the TVS and MESO columns.

Potential problem => The CAT is distributed to NIDS vendors. Thus the potential exists for TVS/ETVS locations to be displayed by the media.

TDA Adaptable Parameter Sets:

• There are now 30 adaptable parameters as opposed to three (3) in Build 9.
• Some of these values, in the form of parameter sets, can be changed (via the URC).
• Four different parameter sets to choose from:

• Default - will produce high PODs and FARs
• Minimized - similar to Build 9 (many undetected TVSs; detected TVSs likely to be significant)
• Squall Line - should enhance performance in this type of event
• Tropical - should enhance performance in this type of event

• Each parameter set has only three (3) editable parameters at the UCP (OSF specified).
• Three (3) additional TDA parameters can be changed at the UCP via the URC:

• Minimum Reflectivity (needs to be well thought out)
• Maximum Pattern Vector Range
• Maximum Number of Elevated TVSs

• More research needed to better utilize the setting of the adaptable parameters.
• Anticipate change in operational philosophy so to properly utilize new parameters.

Elevated TVS (ETVS) Display Toggle:

• PUP/AWIPS operators can toggle display of ETVS symbols on/off.
• This toggle does not affect the TVS Attribute Table or Alphanumeric Product.
• Potential problem => If the PUP display of ETVS symbols is toggled "off", local media would still have the ability to display ETVSs, while we were not.
• Use ETVS output with caution until a better understanding of its utility is developed.

Velocity Dealiasing Algorithm Changes to Support the TDA:

• Will eliminate data dropouts in high shear regions.
• Can not use existence of data dropouts as indicator for a high shear region.
• Now rare to see a TVS false alarm caused by vertically aligned velocity dealiasing errors.

Operational Considerations when TDA-based TVS/ETVS Identified:

--Regarding the TVS

• Consider the TVS' position in relation to its associated storm.
• Consider time continuity, and the storm's range from the radar.
• Beyond 60 km (32.4 nm), TVS most likely triggered by a strong mesocyclone.

• TVS works independently of mesocyclone algorithm.
• If mesocyclone coincident with TVS - take a real close look at this storm.

• Given the following scenarios, radar operator should closely examine the storm:

• TVS adjacent to a strong reflectivity gradient (especially near back of storm)
• TVS near a notch on the right rear flank of a storm
• TVS near tip of an appendage in vicinity of storms' right rear flank

• In tests, algorithm has worked very well on long-lived supercells.
• Inconclusive in its performance when tornadoes occur within squall lines - be aware.

- Regarding the ETVS

• ETVSs have not been shown to score statistically as well as TVSs.
• ETVSs used to indicate rotation aloft.
• May provide better lead times for storms more inclined to produce tornadoes.
• May provide good information when low level data suspect.
• ETVS may provide time/depth continuity when considering issuance of warning.

• Caution - do not issue a tornado warning based solely on algorithm indicated ETVS.

- In General

• Algorithms provide the user with guidance!
• Continue to utilize all available data, tools, and spotter reports.

Build 9 and Build 10 Incompatibility:

• For Build 9 PUP connected to Build 10 RPG (scenario may exist briefly at ILN):

• TVS graphic symbols will be displayed.
• TVS attribute table will appear with Build 10 parameters displayed.
• ETVSs will not be displayed.
• Do not set up TVS/ETVS alerts with Build 9/Build 10 configuration.

• For Build 10 PUP connected to a Build 9 RGP (should not be scenario at ILN):

• TVS graphic symbols will be displayed.
• TVS attribute table will appear with Build 9 parameters displayed.
• ETVSs will not be displayed.
• Do not set up TVS/ETVS alerts with Build 9/Build 10 configuration.

New Hybrid Scan Reflectivity (HSR) Product:

• Based on reflectivity data from the lowest four s (see Sectorized Hybrid Scan

Construction on pg. 30 of Build 10 Training document).

• Assists in determining accuracy of the precip products and the Radar Coded Message.
• HSR product now displayable at the PUP.
• The Tilt Test:

• Areal coverage of echos at 0.5º and 1.5º compared.
• If 75% reduction is found at 1.5º (compared to 0.5º), echos at 0.5º assumed to be clutter and are then removed from further processing. Result will display "LOWEST TILT UNUSED" on the HSR product.

New LRM - Anomalous Propagation Removed (APR) Product:

• LRM APR is an 8-data level reflectivity display.
• It is similar in appearance to the existing Surface to 24,000 ft LRM products.
• It is derived from the output of an algorithm that processes:

• Base reflectivity, velocity, and spectrum width data.

• Algorithm-identified ground targets will be removed.
• The goal - to distinguish weather targets from clutter targets.
• Caution:

• Continue to apply traditional clutter filtering when necessary.
• Algorithm assumes all low level data within 45 km and 1 km depth is clutter!
• Current adaptable parameter values may not be optimum; further tests needed.

Build 10 Enhancements

Can Select Depth of the Lowest Layer of Layer Composite Reflectivity Products (LRM):

• Top of layer remains fixed at 24,000 feet MSL.
• Authority to change is at the URC Level.
• Changes made at the UCP.
• Depth of layer must be 6000 ft.

Time Lapse Default Set to Automatic Continuous Loop:

• CONTINUOUS LOOP box removed from Graphics Tablet

More Detail Noted when Examining User Functions.

Ability to Select a Storm from Any Graphic Attribute Table or Geographical Display:

• In Attribute Table, use cursor to select the cell of interest.
• Info can then be used with the following PUP functions:

• CELL TRENDS
• CURSOR HOME DEFINE
• RECENTER/MAGNIFY
• AZRAN SELECT Used to select various window products such as:

Storm Relative Region, Weak Echo Region, Severe Weather Analysis products, ...

• Possible problem when using the TVS and MESO attribute tables AZRANs here not associated with storm centroids, thus may not properly display CELL TRENDS information if AZRAN of TVS or MESO not within 5 nm of the storm centroid.

Slice Products now Default to the Lowest Tilt:

• Used with 0.5º, 0.54nm resolution products.
• Can not be used with the following:

• Elevation products not displayed with a 0.54nm resolution (e.g., SRR).
• Elevation products for which a 0.54nm resolution is not available in the PUP data base.
• Products not displayed via elevation angles (e.g., VIL, CR)

• Note - Operators can still monitor the PROD RCVD status line and use the DISPLAY PRODUCT box to display incoming products at other elevations and resolutions.

Archive II Status Messages Added at the UCP:

• More detail provided for the current state of the Archive II device at the RDA.
• New status messages available include:

• FST FWD - Tape device is fast forwarding.
• TAPE XFR - Tape device swapping tapes in the "jukebox".
• CK LABEL - Tape device is checking a label.

Note - A number such as "01" after a status message will refer to the tape #.

APUP RPS Lists Increased to 31 Products:

• With this increase from 20 products, narrowband load-shedding a possibility.

Turbulence Algorithm/Products Eliminated.

WSR-88D Focal Point(s) see the following item in the "88D Build 10 Training" document:

• New Utility: BACKFILE (page 44).

All SRM Products Read from Optical Disk will now Time Lapse.

PUP Dial-out line may Automatically Disconnect:

• If the PUP stays connected to an RPG, where data flow is non-existent, an automatic disconnect will be issued.

NIDS Vendors No Longer Get More Products than Intended:

• The default Generation and Distribution Control (GDC) list contains the minimum # of products scheduled for generation each volume scan.
• The URC can add products to the GDC list, but can not subtract from it.
• Any products added to the GDC must not be sent to Other Users (NIDS vendors).
• See example in "Benefit" section on pg. 55 of the "88D Build 10 Training" document.

Archive IV Problems Corrected:

• During Auto-archive PUPDOWN/PUPUP not required to recover system when archive status screen indicates "archive active", but the disk is mounted off.
• If the Cancel Archive command is issued immediately after the A,A,D command, cancellation will now occur, and with the appropriate feedback on the Applications Terminal. This was not the case in earlier builds.
• The system will now correctly accept subsequent archive commands.

WSR-88D Focal Point(s) see the following items in the "88D Build 10 Training" document:

• OPTREAD No Longer Continues to Execute after Disk Fails to Mount On (page 53).

• OPTREAD Software Modified to Add New RPG Mnemonics and Correct Inaccuracies (pages 53-54).
• Product Received Messages will now be Displayed in Training Mode (page 54).

Some PUP Help Screen Corrections:

• In the "PUP Alert Processing Edit Screen"; category 15, MAX 1HR PRECIP now correctly shows unit information to read "inches".
• In the "Product Names and IDs Help Screen", mnemonic for ID #44 correctly identified as SWV.

Graphics No Longer Hang when Using OVERLAYS ERASE Function:

• The ERASE OVERLAYS request will not be carried out if the graphics screen is clear. This use to result in a graphics hang, thus requiring a PUPDOWN/PUPUP.

Line Noisy Status Messages Corrected:

• System corrections will now allow appropriate status messages to be displayed.

USP Product on the PUP RPS List will now Auto-display.

Velocity Dealiasing Algorithm changed to support TDA:

• Data dropouts will no longer occur in regions of high shear.
• Velocity data, previously discarded, will be restored.
• A further attempt, by the algorithm, will be made to find a valid velocity value.

Comms Card Automatically Re-initializes after becoming Inactive:

• Due to a comms hardware problem, loss of data flow from the RPG to the PUP was noted.
• Result of problem - products suddenly stop arriving from the RPG.
• Solution - Comms hardware automatically re-initialized; data flow into PUP from the RPG not lost.
• Resulting system status messages on the PUP graphics display (also on system log):

• "Line xx Initializing".
• "Line xx Init Complete".

User-friendly VCP Sector Definition Implemented:

• Easier to interpret.

WSR-88D Focal Point(s) see the following items in the "88D Build 10 Training" document:

• PUP Help Screen Corrections (Items #1 and #4 on page 57).
• Task Pause during Archive IV Map Merge Corrected (page 58).
• Additional Archive IV Problems Corrected (page 58).