The Integration of Total Lightning into NCAR

1
The Integration of Total Lightning into NCARs
Auto-nowcaster A Status Report

• Nic Wilson
• University of Oklahoma, Vaisala and NCAR-RAL
• Southern Thunder Workshop
• Ft. Worth, TX
• 26 July 2005

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Todays Topics

• Introduction to the Research Project
• Observations from Dallas-Ft. Worth Spring/Summer
  2005
• The Application of Total Lightning Toward the
  Auto-Nowcaster
• Comments and Future Work

3
Southern Thunder
The Band
The Book
4
Southern Thunder
The Tattoo Parlor
The T-shirt
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Research Introduction

• A partnership between the University of Oklahoma,
  Vaisala and NCAR-RAL
• Masters of Science in Professional Meteorology
  Degree Path
• Topic Exploring the application of total
  lightning data toward convective storm nowcasting

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Research Introduction Cont

• NCARs Auto-nowcaster (ANC) was chosen as the
  most advanced nowcasting software package in
  existence today
• Natural relationship existed with Vaisalas LDAR
  II and NCARs ANC both running operationally
  within NWS Ft. Worth
• RAL has research funding from ATEC for eventual
  implementation into the WSMR ANC

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Total Lightning Storm Observations from
Dallas-Ft. Worth Spring/Summer 2005
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LDAR II Products 25 April 2005
2-min. Flash Extent Density
2-min VHF Source Points
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LDAR II Products 25 April 2005
2-min. Flash Initiation Points
4-min. Flash Extent Density
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Why Use Flash Extent Density?

• Very limited research has been done to evaluate
  its effectiveness at lightning cell
  identification and attribute trend analysis
• FED data is gridded and offers more consistency
  than traditional VHF source points, making it
  advantageous for cell identification and
  nowcasting purposes

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What Does FED Represent?

• Maximum FED activity is located downshear from
  the main convective updraft within areas of
  reflectivity gradient greater than 20 dBZ
• The downshear reflectivity contains the largest
  vertical velocity gradients, which enhance charge
  separation
• FED supports non-inductive charging mechanisms

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FED and NIC Mechanisms at Work
On this day -10 C was at 5.5 km and -20 C was at
7 km
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FED and NIC Mechanisms at Work
Significant amounts of ice, graupel and
supercooled water droplets are now suspended
aloft at 5.5 km and above, creating cloud flashes
extending thru the anvil
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Supercell Flash Interaction
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Supercell Flash Interaction
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Splitting Cell FED 2024 UTC
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Splitting Cell 2038 UTC
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Splitting Cell FED 2036 UTC
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Splitting Cell 2043 UTC
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Splitting Cell Cross Section
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Maximum Flash Extent Density Trends Related to
Severe Weather Events
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Maximum Flash Extent Density Trends Related to
Severe Weather Events
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The Application of Total Lightning to Nowcasting
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The Auto-nowcaster
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Auto-nowcaster Background

• An interactive software package that integrates
  multiple meteorological data sets in real-time
  and uses fuzzy logic to combine them and create a
  60-minute convective forecast every 5 minutes
• Currently run over four domains
• 1.) Illinois/Indiana T-Storm Operational
  Research Project (THOR)
• 2.) White Sands Missile Range, NM
• 3.) Beijing, China
• 4.) Dallas-Ft. Worth, TX

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ANCs Products for Ft. Worth

• 60-minute Initiation Likelihood Field
• 60-minute Nowcast Field
• Interactive display systems at NWS Ft. Worth and
  NCARs Aviation Weather Development Laboratory

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KFWS WSR-88D 13 July 2005 2038 UTC
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60-minute Initiation Likelihood Field
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60-minute Nowcast Field
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TITAN Cell Identification

• The thunderstorm, identification, tracking,
  analysis and nowcasting (TITAN) software package
  is used in the ANC to grow, maintain and decay
  ongoing convection
• LDAR II data can supplement the radar data used
  by TITAN to identify storms using certain size
  and intensity thresholds

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TITAN Identification of Cells

• 35 dBZ Cell

• 0.25 FED Cell

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Application of LDAR II Data

• Case study analysis shows that TITAN identifies
  35 dBZ reflectivity cells before 0.25 FED cells
  in DFW
• Total lightning is not effective at assisting
  with initiation forecasts in this region
• However, LDAR II data can complement and improve
  upon the reflectivity-derived attributes
  currently used to forecast storm size and
  intensity

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Total Lightning Latency

• 25 April 2005 Supercell Event
• 23 mins. before the 1st VHF source
• 42 mins. before the 1st 0.25 FED cell
• Total lightning cell identification ineffective
  during warm precipitation processes
• All Other Cases
• 18 mins. before the 1st 0.25 FED cell

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Auto-nowcaster Growth/Decay

• The ANC currently combines four membership
  functions to grow, maintain or dissipate ongoing
  convection. These three are derived from 2.5
  km.-to-troposphere composite reflectivity
• 1.) 35 dBZ TITAN Normalized Area Growth Rate A
  history-weighted normalized trend of the storms
  area greater than 35 dBZ
• 2.) 45 dBZ TITAN Normalized Area Growth Rate
  Same as above but encompasses only the most
  intense convection of a storm
• 3.) Maximum dBZ Ensures that intense convection
  isnt dissipated

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Reflectivity Membership Functions
Wt 0.30
Wt 0.15
Wt 0.20
Wt 0.21
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Ongoing Research at NCAR

• Main Research Thrust Develop LDAR II-based
  membership functions that compliment the current
  reflectivity-derived fields and improve the ANCs
  overall performance
• Secondary Thrusts
• 1.) Evaluate the effectiveness of flash extent
  density
• 2.) Identify underlying physical relationships
  between reflectivity and total lightning
• 3.) Identify the temporal and spatial limits for
  the use of LDAR II data as a nowcasting tool

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TITAN-Derived Cell Attributes to Predict
Growth/Decay
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60-min Area Correlation
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FED Membership Functions
0.25 FED Normalized growth rate emulates the 35
dBZ field
FED max emulates the dBZ max membership function
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ANC Membership Function Performance
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Growth Forecast Performance
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Growth Forecast Performance
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Decay Forecast Performance
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Decay Forecast Performance
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Decay Forecast Performance
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Forecasting Storm Intensity Using Total Lightning
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60-min Max dBZ Correlation
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Intensity Membership Functions
Reflectivity derived membership function
FED derived membership function
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Hypothetical ANC Membership Function Performance
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ANC Growth/Decay Problems
LDAR II Range Issues
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ANC Growth/Decay Problems
Assigning Attributes to Storm Cells
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Future Research

• Statistical forecast verification using the newly
  created total lightning membership functions
  within the Ft. Worth ANC
• Look at how the FED TITAN storm motion vectors
  compare to dBZ cross-correlation
• Possible adjustments to how growth/decay is
  handled within the ANC?
• Implementation of the total lightning fields
  operationally in Ft. Worth and WSMR

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Future Presentations

• AMS Radar Conference Albuquerque, NM Wed. Oct.
  26th , 2005 Session 6R 1145am
• The Complementary Use of TITAN-derived
  reflectivity and total lightning thunderstorm
  cells
• AMS Meteorological Applications of Lightning
  Conference Atlanta, GA Jan. 2006
• Nic Wilsons Contact Information
• Email nwilson_at_ou.edu
• Project Website http//weather.ou.edu/nwilson/pr
  oject.html