Measurements of Lightning Parameters Using Correlated Video and NLDN Data E. Philip Krider, Christopher J Biagi, Kenneth L Cummins, Stacy Fleenor, and Kenneth E. Kehoe Institute of Atmospheric Physics, University of Arizona

Video and NLDN Data

NLDN Report Date/Time: 8/05/05 03:39:18.562 Azimuth: 220° Range: 24 km Peak Current: +85.1 kA

The U.S. National Lightning Detection Network (NLDN)

2005, July 3 – 14 Mostly Individual, Short Lived Cells, in the late afternoon hours, a few supercells, and 2 MCS 2003,2004, April Mostly MCS

2003,2004,2005 Monsoon Storms August, September Southern Arizona 2003 – 671 Flashes 2004 – 426 Flashes 2005 – 390 Flashes Total Flashes = 1487

July,

Texas and Oklahoma 2003 – 59 Flashes 2004 – 308 Flashes

The Midwest 2005 – 412 Flashes

Total Flashes = 367

Total Flashes = 412

Lightning Parameters

Estimated Peak Current (Ip) of First Strokes Number of Strokes per Flash (Multiplicity) Number of Ground Contacts per Flash

How do these parameters vary with region?

Regional Comparisons No. of Video Strokes

No. of NLDN Strokes

NLDN Flash DE (%)

NLDN Stroke DE (%)

Mean Ip (SD) (kA)

Median Ip (kA)

94

94

-19.7 (10.5)

-16.9

AZ 2003-2004 First-strokes

1012

953

SS with NGC

444

355

80

-15.0 (11.2)

-15.4

SS in a PEC

1894

1247

67

-14.9 (8.3)

-12.7

86

-19.2 (17.8)

-13.8

TX-OK 2003-2004 First strokes

318

273

92

SS with NGC

126

101

80

-15.6 (8.5)

-13.9

SS in a PEC

338

270

80

-13.9 (8.0)

-12

80

-23.2 (13.6)

-19.5

GP 2005* First-strokes

112

90

91

SS with NGC

61

50

82

-19.4 (8.6)

-17.6

SS in a PEC

130

100

77

-17.5 (11.3)

-13.7

*Flashes not reported by the NLDN were assumed to have a negative polarity if the flash occurred in a negative dominated storm or if the flash had multiple strokes. All other uncorrelated flashes were assumed to be positive.

Peak Current for Negative First Strokes

Peak Current for Negative First Strokes

Peak Current for Negative First Strokes

The mean video multiplicity of negative flashes in AZ, TX-OK, and the GP for low and high |Ip|.

First Stroke Amplitude

No. of Flashes

% Single Stroke

Multiplicity Mean (SD)

AZ 2003-2004 |Ip| ≤ 10 kA

83

45

2.4 (2.0)

|Ip| > 10 kA

893

28

3.6 (2.7)

TX-OK 2003-2004 |Ip| ≤ 10 kA

72

52

2.3 (2.1)

|Ip| > 10 kA

238

32

2.7 (1.9)

GP 2005 |Ip| ≤ 10 kA

8

75

1.6 (1.3)

|Ip| > 10 kA

82

44

2.5 (1.9)

Percentage of negative flashes that produced the number of ground contacts (GC)

No. of GC

AZ (%)

TX-OK (%)

GP (%)

1

68.3

70.0

68.0

2

23.7

22.3

16.1

3

6.0

8.4

10.7

4

1.4

0

6.25

5

0.6

0.3

0

Mean GC per flash

1.42

1.40

1.56

7/10/05 5 pm

7/11/05 9 pm

N = 45, 95% positive

N = 106, 89% positive Tornado Warning

7/7/05 4 pm N = 13, 100% positive

7/05/05 4pm N = 20, 0% positive

7/6/05 5 pm N = 30, 10 % positive

7/5/05 5 pm N = 12, 100% positive 7/13/05 8 pm N = 15, 0% positive 7/03/05 7pm

7/06/05 1pm

N = 34, 0% positive

N = 23, 0% positive

7/4/05 4 pm

7/4/05 9 pm

N = 10, 100% positive

N = 16, 93% positive

Tornado Warning

Tornado Warning

Table 1. Summary of Measurements in the Great Plains in 2005

Date

Recording Interval (min)

Video Flashes

Flashes (%) Reported by NLDN

Video Strokes

Strokes (%) Reported by NLDN

Mean Video Multiplicity

Session Polarity (%)

3 July

60

31

30 (97)

75

61 (81)

2.42

Negative (100)

4 July

28

10

7 (70)

10

7 (70)

1.00

Positive (100)

5 July

72

16

15 (94)

25

18 (72)

1.56

Positive (94)

5 July

41

4

4 (100)

5

5 (100)

1.25

Positive (100)

6 July

18

20

19 (95)

57

46 (81)

2.85

Negative (100)

6 July

23

12

12 (100)

13

12 (92)

1.08

Positive (92)

6 July

104

23

19 (83)

51

40 (78)

2.22

Negative (100)

6 July

6

3

3 (100)

15

10 (67)

5.00

Negative (100)

7 July

103

30

28 (93)

33

31 (94)

1.10

Positive (100)

7 July

31

8

8 (100)

33

26 (79)

4.13

Negative (100)

7 July

14

13

12 (92)

14

13 (93)

1.08

Positive (100)

10 July

18

6

5 (83)

6

5 (83)

1.00

Positive (100)

10 July

83

45

42 (93)

49

43 (88)

1.09

Positive (98)

11 July

84

88

78 (89)

105

93 (89)

1.19

Positive (92)

11 July

11

12

10 (83)

12

10 (83)

1.00

Positive (100)

11 July

10

6

6 (100)

6

6 (100)

1.00

Positive (100)

13 July

60

15

14 (93)

37

32 (86)

2.47

Negative (100)

Positives

227

204 (90)

237

210 (89)

1.04

Negatives

111

104 (94)

300

239 (80)

2.70

Bipolars

4

4 (100)

9

9 (100)

2.25

All Data

342

312 (91)

546

458 (84)

Estimated Peak Current - Negative and Positive First Strokes 14 N Mean Ip Median Ip SD

12

Negative 91 23.3 kA 19.6 kA 13.6 kA

Positive 205 48.7 kA 44.7 kA 24.1 kA

8

6 Negative Positive 4

2

Ip (kA)

10 5 11 0 11 5 12 0 12 5 13 0 13 5 14 0 14 5 15 0

95 10 0

85 90

80

70 75

60 65

50 55

40 45

30 35

20 25

10 15

5

0 0

Number

10

Peak Current for Positive First Strokes

200 45

180 40

N = 104 Flashes Neg. Mean: 2.81 strokes/flash

Number of Flashes

30

25

20

15

Number of Flashes

160 35

N = 204 Flashes Pos. Mean: 1.04 strokes/flash

140 120 100 80 60

10

40

5

20 0

0 1

2

3

4

5

6

7

8

9

10

1

11

2

3

4

5

6

7

8

9

10

Strokes per Flash

Strokes per Flash

200

80

180

70

N = 104 flashes Neg. Mean: 1.58 contacts/flash

50

40

30

Number of Flashes

Number of Flashes

160

60

140

N = 204 flashes Pos. Mean: 1.02 contacts/flash

120 100 80 60

20 40

10

20 0

0 1

2

3

Ground Contacts per Flash

4

1

2

3

Ground Contacts per Flash

4

11

0 ms

277 ms

Estimated Peak Current - Negative Strokes 20 First Strokes 91 N 23.3 kA Mean Ip 19.6 kA Median Ip 13.6 kA SD

18 16

Normal Subsequent 98 17.2 kA 13.7 kA 11.1 kA

14

10 8 First Strokes

6

Normal Sub. 4 2

Ip (kA)

75

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0

0

Number

12

Estimated Peak Current - Negative Strokes 12

N Mean Ip Median Ip SD

10

First Strokes 91 23.3 kA 19.6 kA 13.6 kA

New Contacts 47 18.9 kA 16.7 kA 8.7 kA

6

4 First strokes New Ground Contact 2

Ip (kA)

75

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0 0

Number

8