Lightning ClimatologyOklahoma Lightning Mapping Array

May - September, 2004 - 2005

Paul Krehbiel

New Mexico Tech

September 28, 2005

Lightning Mapping Arrays (LMAs)

● Utilize time-of-arrival technique

● Consist of 10-12 stations over 50-70 km diameter area

● Passive system: locates impulsive radio frequency signals produced by

lightning (radio 'static')

● Listens in a locally unused VHF TV channel (e.g., Ch 3, 5, 8)

● Produce observations in near real-time (1-2 minute delay)

● Provide good spatial accuracy and temporal resolution

Existing systems:

● New Mexico Tech LMAs: Northern Alabama (NASA/Huntsville),

Oklahoma (OU/NSSL), Langmuir Laboratory (NMT), WSMR, ...

● Vaisala (formerly GAI) LDAR II: Dallas/Ft. Worth, Houston

(TAMU),

Kennedy Space Center.

Oklahoma LMA data:

Real time observations:• Cover a large area

(400-500 km diameter)• 3D over 200-300 km

diameter area• Data are simultaneous;

short update times

(2 min)

Useful information:• Plan source densities

(vertically integrated)• Altitude vs. time

source density plots

Lightning activity shows

where strong convection

is occurring, and if

intensifying or weakening

(See lightning.nmt.edu)

Texas

Zoomed-in example:

Density of Points Display

Moore, OK tornadic storm

May 10, 2003

10 min of observations

(NLDN events in green)

-> xlma analysis software

Climatology Data from Oklahoma LMA

The following slides show on a month-by-month basis the number of

located LMA sources as a function of the day of the month and the

hour of each day, in the form of a 3-dimensional bar graph

(generated using the ‘bar3’ plotting tool of Matlab). The vertical bars

indicate the number of sources per hour on a logarithmic scale to

prevent large mesoscale systems from dominating the plots. The units

are kilosources/hour, with a threshold value of 1000 sources/hour

being applied to discriminate against weakly-detected, distant storms

from cluttering up the presentation (any storm of reasonable size and

within range of the LMA will produce several thousand sources/hour).

To determine what the storms look like during an active period, see

http://lightning.nmt.edu/oklma.

(Bar graphs are shown only for April through September but are

available for the entire year.)

Number of located LMA sources, April 2004, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, April 2005, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, May 2004, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, May 2005, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, June 2004, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, June 2005, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, July 2004, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, July 2005, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, Aug. 2004, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, Aug. 2005, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, Sept. 2004, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

Number of located LMA sources, Sept. 2005, Oklahoma

(Daylight ~12-24 UTC; 7 am – 7 pm CDT)

For real-time data plots, archived daily and hourly,

see http://lightning.nmt.edu/oklma

Lightning ClimatologySTEPS 2000 Lightning Mapping Array

(NW Kansas, E Colorado, SW Nebraska)May 24 – August 10, 2000

Two supercell storms in

NW Kansas–SW Nebraska

- June 7, STEPS 2000

-13 station LMA network

- Close storm: Low Precip

- Far storm: High Precip

- 10 min time interval

- ~Continuous IC lightning

- Inverted polarity storms

(deep mid-level + charge)

- Only one NLDN event

- negative CG (real?)

- Major advantage of total

lightning vs. CG only

Note:

Major Ch 3 TV interference,

data processed with auto-

thresholding.

Aircraft track and storms,

May 25, STEPS 2000

(Aircraft being charged

while flying through down-

wind cirrus/anvil cloud)

Height vs Time

Plan View

Height vs E-W

Height vs N-S

Example of Highly Dendritic Negative CG flash

Number of located LMA sources, May 2000, STEPS

(Daylight ~12-02 UTC; 6 am – 8 pm MDT)

Number of located LMA sources, June 2000, STEPS

(Daylight ~12-02 UTC; 6 am – 8 pm MDT)

Number of located LMA sources, July 2000, STEPS

(Daylight ~12-02 UTC; 6 am – 8 pm MDT)

Number of located LMA sources, August 2000, STEPS

(Daylight ~12-02 UTC; 6 am – 8 pm MDT)

(The End)

ti=t xi−x 2y i−y 2zi−z2

c

impulsive lightning event

at (x, y, z; t)

ithstation x i , y i , zi ,signal arrives at time ti

−measure ti at N≥4 50ns accuracy −solve for x , y ,z ;t 4 unknowns

Time-of-Arrival Concept:

xy

z

Oklahoma Lightning Mapping Array11 station network, 50 km diameterReal-time processing & display

University of Oklahoma/National Severe Storms Laboratory

Oklahoma LMA Station

North Alabama Lightning Mapping Array (NASA)

Map (10 stations)

http://branch.nsstc.nasa.gov/

One hour of real-time data

New Mexico LMA Networks

Portable LMA System (Vortex II, DC Network, DC3?)

• Electronics housed in shielded

thermoelectric cooler enclosure• Operate from external 12 VDC battery and/or

power supply. ~12 (+48) watts power• Battery operation: 48+ hours (w/out cooling)

20+ hours (with cooling)• Lightweight (10 lbs)

• ¼ wave ground plane antenna

(Ch. 8 shown; 180-186 MHz)• Connected to receiver in box by

coaxial cable • Other external connectors:

GPS antenna, ethernet, 12 VDC