The Functionality of a New Radar Software Package: GRLevel2 Analyst Edition

1
The Functionality of a New Radar Software
Package GRLevel2 Analyst Edition

• Ted Keller
• Senior Meteorologist
• KOLR/KSFX-TV
• Springfield, Missouri

2

• Im from Springfield, Missouri

3
This Presentation

• Why I decided to give this talk
• Review of AE software capabilities
• Using AE in real-time
• Considerations for using AE on air
• Establishment of a radar resource or dialog
  program (via a web site?)

4
My Radar Experience

• WSR-57C (first hook echo)
• Kavorus RADAC
• WSI 1010N (level 3, NIDS)
• Baron FasTrac Millennium

5
The NIDS Years

• Useful for quick diagnostic storm attributes
• NIDS images poor quality hard to see many
  features
• Storm attributes delayed from images
• Storm attributes not perfect
• The whole NIDS set up discouraged any detailed
  analysis

6
Why This Talk?

• Im excited! AE has opened a whole new world of
  radar analysis
• I come from background with no live radar
  experience
• Im certainly no radar expert but I believe I
  represent many of you with similar backgrounds
  and experiences
• AE has improved severe weather coverage!

7
GR2 Analyst Edition (AE)

• AE reads Level II data from the NWS 88D radar
  (real-time or archived)
• It was designed as a volume-rendering tool
  allowing users to view radar data in three
  dimensions plus time (4D)
• AE is also a very slick 2D radar viewer with lots
  of useful features

8
GR2 Analyst Edition (AE)

• AE uses hail detection algorithms patterned after
  those developed by the National Severe Storms Lab
  (NSSL)
• The environmental data used by the algorithms can
  be entered by hand or automatically input using
  RUC objective analysis data
• AE generates two hail parameters
• POSH, Probability of Significant Hail
• MEHS, Maximum Estimated Hail Size

9
GR2 Analyst Edition (AE)

• The user can input storm motion vectors used in
  the calculation of storm relative velocity (SRV)
• AE calculates vertically integrated liquid (VIL)
  density (VILD)
• VILD takes the entire storm height into
  consideration and uses all reflectivity
  (including hail) in its calculation

10
AE 2D Fields

• Base reflectivity (BR)
• Base Velocity (BV)
• Storm Relative Velocity (SRV)
• Spectrum Width (SW)
• Echo Top (ET)
• Vertically Integrated Liquid (VIL)
• Vertically Integrated Liquid Density (VILD)
• Probability of Significant Hail (POSH)
• Maximum Expected Hail Size (MEHS)

11
2D Features

• Elevation scan selection
• Derived products
• Screen markers
• Storm motion vector
• 2D slice
• Placefiles and shapefiles
• Exporting images

12
Place and Shape Files

• Note the radar data is level 3 in this example

13
The Volume Rendering Engine

• Four viewable fields
• Base reflectivity
• Base velocity
• Storm relative velocity
• Spectrum width

• Allows storms to be viewed in three dimensions
• Two modes
• Lit Surface, uses an alpha table to produce
  semi-transparent dBZ surfaces
• Isosurface, users can step through dBZ levels

14
Lit Surface Example
What is this?

• Solid 50 dBZ surface (red)
• Semi-transparent 45 dBZ shell (gold)

15
Isosurface Example

• An externally produced animation showing
• successive layers of dBZ being stripped away

16
3D Alpha Table

• Users can select which dBZ levels are visible and
  their degree of transparency by manipulating an
  alpha color table

Solid above 50 dBZ
shell at about 45 dBZ
17
Strong Tornado
18
Where Are the Attributes?

• At present, there are none in AE
• The issues are what to offer and how to display
  it, not whether it should be done
• Velocity data noisy data subject to aliasing
  issues

19
Current Cut-In Policy

• Definite
• At least one live cut-in for all tornado warnings
• Subjective
• Preemptive Strike a cut-in for a storm likely
  to become tornadic
• Ongoing coverage of tornado warnings that fall
  short of wall-to-wall
• Most severe thunderstorm warnings are not covered
  with a cut-in

20
Preemptive/Ongoing Tornado Coverage

• Just using AE in 2D with Level II data is a huge
  improvement!!
• In 3D, features such as BWERs are plain to see
• What about the tornado finger? (fickle finger
  of fate)
• AE definitely aids the decision making process

21
Noteworthy 3D Features

• Tornado tube
• Hail cores
• Bounded Weak Echo Regions (BWERs)
• Overhangs
• Triple Backscatter
• Overshooting Tops

22
An Example of a Three Body Scatter Spike (TBSS)
23
Non-Tornadic Storms

• Cut-in decision based on general storm intensity,
  weighed heavily by population density!
• Can AE provide enough detailed storm information
  to justify more cut-ins for non-tornadic events?

24
Finding Hail Cores in 4D

• AE makes it easier to visualize developing and
  descending hail cores using the volume rendering
  engine
• AE also has sophisticated hail probability and
  estimated hail size algorithms

25
Extreme Hail Cores
26
Hail Size - MEHS
Tennis Ball (2.5) sized hail near Moody, MO AE
estimated 2.76 4 minutes before the reported
time of the hail
27
Using AE On-Air

• It should first be stated that AE in its present
  form was not designed specifically for on-air use
• If future builds lean in this direction, there
  are only two considerations
• Would AE add meteorological value?
• How does it look? Is it understandable?

28
Just the Facts

• I tend to lean toward the Joe Friday approach
  to live cut-ins meaning I believe the public is
  best served by clear graphics which state what,
  where and when
• On the other hand, this is TV and where would we
  be without a certain level of enthusiasm for new
  products and visualization techniques?

29
How Does it Look? Is it Understandable?

• AE has done a great job giving the user graphical
  options to make the product look fantastic!
• Will viewers understand what they are looking at?
  Perhaps.
• Need accurate geographical reference points
• Must be selective about what to show and careful
  in your explanation
• For stations already committed to 3D radar views,
  AE is an improvement!

30
Would AE Add Meteorological Value?

• This is a tougher question
• A few candidates
• Timing of hail core descent
• Tornadic signatures
• Other undiscovered signatures

31
Future Investigations and Projects

• Database of hail size verification
• New 3D structures or signatures?
• New 3D velocity structures or signatures
• Convincing management to invest in a stand alone
  computer for proper on-air testing
• Establishing a radar resource web site

32
Helical Flow

• Example of twisted inbound/outbound couplet in 3D
  velocity data
• New signatures here? I dont know, Ive never
  seen images like this before, real-time or
  otherwise.

33
Level 2 Radar Data(not a comprehensive list!)

• Allison House (placefiles and data)
• University of Iowa (non-commercial)
• National Climate Data Center (archive only)