Cloud Flash Evaluation Issues and Progress Report

Don MacGorman, NOAA/NSSL

Al Nierow, FAA

Dennis Boccippio, NASA/MSFC

Evaluation of NLDN Cloud Flashes

• Compare times and reliability of first storm detection (various definitions of detection)

• Compare with higher cloud flash detection efficiency

• Determine whether NLDN cloud flash detection is biased

• Develop prototype cloud flash products for AWIPS and WDSSII

PROGRESS

• Improved OK-LMA network- added station and real-time link to old station

- improved real-time data retrieval

• Collected LMA data and NLDN cloud flash data for May – data collection continuing

• Set up real-time OK-LMA data feed to NSSL and to Norman NWSFO (AWIPS and WDSSII)

• Generation of real-time LMA products for WDSSII and AWIPS ready to begin

• FSL’s development of prototype AWIPS NLDN cloud flash products to begin in June

Real-time Datafrom

OK-LMA06-13-05

Comparisonof CG versusAll Lightning

21 June 2000

15-min accumulationsending at

0015 UTC & 0300 UTC

10 km X 10 km grid

Ground Strike Points Only All Lightning

ConvectiveRegionFlash

TELEXMesoscale Convective

System19 June 2004

Modeled CLD DE: NLDN-based Test Network – Spring 2004

Lightning Comparisons 0141:49 - 0200:07 UTC 1 May

2004• Fort Worth WSR-88D Base Reflectivity Image from 0204 UTC 13 October 2001

DFW LDAR II SourcesDFW LDAR II Flash

Initiation Points

LF Cloud Sources (Red), High DE Poly (Blue), Low DE Poly

(Green)

NLDN CG Flashes

LF Cloud Sources (Red) and NLDN CG

Strokes (Green)

Quantitative Determinationof CLD DE

DateLDARFlashes

NLDN CLDFlashes

NLDN CGFlashes

SmallPositive Flashes IC/CG Ratio

LF CLD DE - small posas CLD

ModeledCLD DE

5/1/04 537 50 128 22 4.1 16.7 15-255/13/04 58 9 19 0 2.1 23.1 >25

5/1/04 122 27 39 8 2.9 38.5 >255/1/04 381 72 135 29 2.6 36.7 >25

•Steps:

• Remove all LF CLD events associated with CG (1 sec)

• Determine LDAR flash initiation points

• Remove all except one event LF CLD event per LDAR initiation point (1 sec)

• Move small positives (< 10kA) into LF CLD category

• Compute statistics

“Good” example – Various supercells

October 10, 2001

0

20

40

60

80

100

20:0

0:00

20:3

0:00

21:0

0:00

21:3

0:00

22:0

0:00

22:3

0:00

23:0

0:00

23:3

0:00

0:00

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0:30

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1:00

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1:30

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2:00

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2:30

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3:00

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3:30

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4:00

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4:30

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5:00

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5:30

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6:00

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6:30

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7:00

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7:30

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8:00

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8:30

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9:00

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9:30

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10:0

0:00

10:3

0:00

11:0

0:00

11:3

0:00

12:0

0:00

12:3

0:00

13:0

0:00

LDAR

LF CLD

NLDN CG

The higher performance periods are when the storms are closer to the heart of the network (need to confirm)

“Poor” Example – large squall line

October 12, 2001

050

100150200250300350400450

22:0

0:00

22:2

3:00

22:4

6:00

23:0

9:00

23:3

2:00

23:5

5:00

0:18

:00

0:41

:00

1:04

:00

1:27

:00

1:50

:00

2:13

:00

2:36

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2:59

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3:22

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3:45

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4:08

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4:31

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4:54

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5:17

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5:40

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6:03

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6:26

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6:49

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7:12

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7:35

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7:58

:00

8:21

:00

8:44

:00

LDAR

LF CLD

NLDN CG

We typically see a limit of 50-100 LF CLD events/second from a local region, presumably due to communication rate limitations and the simple location algorithm (non-RPS)

“Good” Example –airmass cells

June 29-30, 2001

05

101520253035404550

23:3

0:00

23:4

0:00

23:5

0:00

0:00

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0:10

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0:30

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0:40

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0:50

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1:00

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1:10

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1:20

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1:30

:00

LDAR

LF CLD

NLDN CG

Climatological differences will affect comparative thunderstorm-detection

performance of using CG only versus using all types of lightning.

CG TIME LAG FOR

OKLAHOMA STORMS

7% had no CG flashes

18% had CG within 1 min

50% had CG within 5 min

75% had CG within 11 min

CG TIME LAG FOR

DFW STORMS

10% had no CG flashes

14% had CG within 1 min

50% had CG within 8 min

74% had CG within 23 min

CG TIME LAG FOR

HIGH PLAINS STORMS

41% had no CG flashes

4% had CG within 1 min

50% had CG within 37 min

59% had CG within 55 min

Cloud Flash to Ground Flash Ratio

from Boccippio et al. (2001)

%

Mapped PointsColor-coded

by Time

Grided PointsColor-codedBy Density

Lightning Comparison 0141:49 - 0200:07 UTC

1 May 2004

• Fort Worth WSR-88D Base Reflectivity Image from 0204 UTC 13 October 2001

DFW LDAR II SourcesDFW LDAR II Flash

Initiation Points

Plan Projection of Lightning Density

29-30 June 2000

Kansas Supercell Storm

8 May 2003

Tornadic Supercell

Lightning density in 5-minute moving interval

NO

RT

H (

km)

-200

200

-200 200EAST (km)

0

20

0

ALT

ITU

DE

(km

)

20ALTITUDE (km)

OvershootingTop

13 June 1998

OklahomaSupercell Storm

EAST

125 km

125

km

NO

RT

H

20 km

ALTITUDE

ALT

ITU

DE

20 k

m

Lightning density for moving 3-minute interval

Courtesy of New Mexico Institute of

Mining and Technology

+CG to All CG Ratio

Orville and Huffines (2001)