Transcript Slide 1

The Functionality of a New
Radar Software Package:
GRLevel2 Analyst Edition
Ted Keller
Senior Meteorologist
KOLR/KSFX-TV
Springfield, Missouri
I’m from Springfield, Missouri
Much of our “skyline” is due to this guy
Missouri State University
Perhaps many of you may be more familiar with Branson, Missouri
This Presentation
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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?)
My Radar Experience
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WSR-57C (first hook echo)
Kavorus RADAC
WSI 1010N (level 3, NIDS)
Baron FasTrac Millennium
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
Why This Talk?
• I’m excited! AE has opened a whole new
world of radar analysis
• I come from background with no live radar
experience
• I’m certainly no radar expert but I believe I
represent many of you with similar
backgrounds and experiences
• AE has improved severe weather
coverage!
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
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
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
AE 2D Fields
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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)
2D Features
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Elevation scan selection
Derived products
Screen markers
Storm motion vector
2D “slice”
Placefiles and shapefiles
Exporting images
Place and Shape Files
Note: the radar data is level 3 in this example
The Volume Rendering Engine
• 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
• Four viewable fields:
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Base reflectivity
Base velocity
Storm relative velocity
Spectrum width
Lit Surface Example
What is this?
• Solid 50 dBZ surface (red)
• Semi-transparent 45 dBZ “shell” (gold)
Isosurface Example
An externally produced animation showing
successive layers of dBZ being stripped away
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
Strong Tornado
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
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
Preemptive/Ongoing Tornado
Coverage
• Just using AE in 2D with Level II data is a
huge improvement!!
• In 3D, features such as BWER’s are plain
to see
• What about the “tornado finger”? (“fickle
finger of fate”)
• AE definitely aids the decision making
process
Noteworthy 3D Features
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Tornado tube
Hail cores
Bounded Weak Echo Regions (BWER’s)
Overhangs
Triple Backscatter
Overshooting Tops
An Example of a
Three Body
Scatter Spike
(TBSS)
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 nontornadic events?
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
Extreme Hail Cores
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
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?
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?
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!
Would AE Add Meteorological Value?
• This is a tougher question
• A few candidates:
– Timing of hail core descent
– Tornadic signatures
– Other undiscovered signatures
Future Investigations and Projects
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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
Helical Flow
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Example of twisted inbound/outbound couplet in 3D velocity data
New signatures here? I don’t know, I’ve never seen images like this before,
real-time or otherwise.
Level 2 Radar Data
(not a comprehensive list!)
• Allison House (placefiles and data)
• University of Iowa (non-commercial)
• National Climate Data Center (archive
only)