Total Lightning Characteristics in Mesoscale Convective Systems

Total Lightning Total Lightning Characteristics in Characteristics in

Mesoscale Convective Mesoscale Convective

SystemsSystems Don MacGormanDon MacGorman

NOAA/NSSLNOAA/NSSL

& Jeff Makowski& Jeff MakowskiOU School of MeteorologyOU School of Meteorology

Data SourcesData Sources LightningLightning

- Oklahoma Lightning Mapping Array (OK-Oklahoma Lightning Mapping Array (OK-LMA)LMA)

- National Lightning Detection Network National Lightning Detection Network (NLDN)(NLDN)

National composite base-scan radar National composite base-scan radar reflectivity reflectivity

Level II base-scan radar reflectivity Level II base-scan radar reflectivity GOES infrared satelliteGOES infrared satellite

From MacGorman et al. (2008)

MethodologyMethodology Studied 30 MCSs which were within the OK-LMA Studied 30 MCSs which were within the OK-LMA

domain for >3 hours and isolated from domain for >3 hours and isolated from neighboring convection between 2003 and 2009neighboring convection between 2003 and 2009

Classified each MCS according to mode of Classified each MCS according to mode of organization organization

Analyzed OK-LMA flash initiations and NLDN CG Analyzed OK-LMA flash initiations and NLDN CG strikes relative to radar reflectivity and IR cloud strikes relative to radar reflectivity and IR cloud shieldshield

Computed cloud shield area < -52, -54, -60, -66, Computed cloud shield area < -52, -54, -60, -66, and and

-72 ˚C and minimum brightness temperature for -72 ˚C and minimum brightness temperature for each infrared satellite scan each infrared satellite scan

Lightning SummaryLightning Summary

21% of all flashes were cloud-to-ground (CG) 21% of all flashes were cloud-to-ground (CG) strikesstrikes

13% of all CGs lowered positive charge to 13% of all CGs lowered positive charge to groundground

Maximum total flash rate (average over 30 min Maximum total flash rate (average over 30 min period) across all cases was 700 flashes per period) across all cases was 700 flashes per minute (fpm) with average maximum flash rate minute (fpm) with average maximum flash rate of 179 fpmof 179 fpm

Maximum CG flash rate (average over 30 min Maximum CG flash rate (average over 30 min period) across all cases was 180 fpm with period) across all cases was 180 fpm with average maximum flash rate of 37 fpmaverage maximum flash rate of 37 fpm

OK -LMA Initiation Points and OK -LMA Initiation Points and Radar Reflectivity for a Radar Reflectivity for a

Symmetric MCSSymmetric MCS

LMA initiation points for 10-min period centered on 0435 UTC, 12 June 2003

CG Flashes and Radar CG Flashes and Radar Reflectivity for 12 June Reflectivity for 12 June

2003 MCS2003 MCS

‘+’ indicates positive ground strike

CG Flashes and Radar CG Flashes and Radar Reflectivity for 14 May 2003 Reflectivity for 14 May 2003

MCSMCS

‘+’ indicates positive ground strike

OK-LMA Initiation Points, OK-LMA Initiation Points, NLDN Ground Strikes and NLDN Ground Strikes and Radar Reflectivity for an Radar Reflectivity for an

Asymmetric MCSAsymmetric MCS

LMA initiation points (white) and NLDN ground strikes (black) for 10-min period centered on 1135 UTC, 6 July 2004

OK-LMA Initiation Points and OK-LMA Initiation Points and Radar Reflectivity for an Radar Reflectivity for an

Unclassifiable MCSUnclassifiable MCS

LMA initiation points for 10-min period centered on 0805 UTC, 22 August 2005

OK-LMA Initiation Points OK-LMA Initiation Points and Radar Reflectivity for 1 and Radar Reflectivity for 1

July 2004 MCSJuly 2004 MCS0405 UTC

0605 UTC

0805 UTC

Composite Mean of Total Composite Mean of Total and CG Flash Ratesand CG Flash Rates

Total Lightning CG Lightning

0.00

0.20

0.40

0.60

0.80

1.00

-400 -200 0 200 400 600

Time Relative to Peak (min)

Per

cen

t o

f P

eak

6/3/2003

6/4/2003

6/19/2004

6/17/2004

7/1/2004

7/4/2005

7/5/2005

8/21/2005

8/22/2005

8/29/2005

5/8/2007

5/9/2007

6/24/2007

8/19/2007

6/3/2009

5/27/2008

Mean

0.00

0.20

0.40

0.60

0.80

1.00

-400 -200 0 200 400 600

Time Relative to Peak (min)

Per

cen

t o

f P

eak

4/24/2003

5/14/2003

6/3/2003

4/30/2004

7/1/2004

7/4/2005

7/5/2005

8/21/2005

8/22/2005

8/29/2005

5/8/2007

5/9/2007

8/19/2007

6/2/2009

6/3/2009

Mean

Total and CG Lightning Total and CG Lightning Histograms for 19 August Histograms for 19 August

2007 MCS2007 MCS

0

800

1600

2400

100 300 500 700 900 1100 1300 1500

Time (UTC)

Nu

mb

er o

f T

ota

l Fla

shes

0

200

400

600

Nu

mb

er o

f C

G F

lash

es

Total activity denoted by bars

CG activity denoted by solid line

Total CG and +CG Flash Total CG and +CG Flash Histograms for 19 August Histograms for 19 August

2007 MCS2007 MCS

Total CG activity denoted by bars

+CG activity denoted by bars

0

200

400

600

100 300 500 700 900 1100 1300 1500

Time (UTC)

Nu

mb

er

of

To

tal C

Gs

0

10

20

30

40

Nu

mb

er

of

+C

Gs

Infrared Satellite and Radar Infrared Satellite and Radar Reflectivity Overlaid with OK-Reflectivity Overlaid with OK-LMA Initiation Points for 30 LMA Initiation Points for 30

May 2007 MCSMay 2007 MCS

1105 UTC

Infrared Satellite and Radar Infrared Satellite and Radar Reflectivity Overlaid with OK-Reflectivity Overlaid with OK-LMA Initiation Points for 21 LMA Initiation Points for 21

June 2004 MCSJune 2004 MCS

1105 UTC

Maximum Total and CG Flash Maximum Total and CG Flash Rates vs. Maximum -52 ˚C Rates vs. Maximum -52 ˚C

Cloud Shield AreaCloud Shield Area

Total Lightning CG Lightning

0

2000

4000

6000

8000

10000

0 100000 200000 300000

-52 °C Cloud Shield Area (km2)

Ma

xim

um

10

-min

To

tal F

las

h R

ate

0

500

1000

1500

2000

0 100000 200000 300000

-52 °C Cloud Shield Area (km2)

Max

imu

m 1

0-m

in C

G F

lash

Rat

e

Maximum Total and CG Flash Maximum Total and CG Flash Rates vs. Minimum Cloud Rates vs. Minimum Cloud

Shield TemperatureShield Temperature

Total Lightning CG Lightning

0

2000

4000

6000

-80-70-60-50

Minimum Cloud Shield Temperature (°C)

Ma

xim

um

10

-min

To

tal F

las

h R

ate

0

500

1000

1500

2000

-80-70-60-50

Minimum Cloud Shield Temperature (°C)

Ma

xim

um

10

-min

CG

Fla

sh

Ra

te

Total and CG Flash Rates Total and CG Flash Rates vs. vs.

Maximum -52 ˚C Cloud Maximum -52 ˚C Cloud Shield Growth Rate Shield Growth Rate

Total Lightning CG Lightning

0

2500

5000

7500

0 400 800 1200 1600

Maximum -52 °C Cloud Shield Growth Rate (km2 min-1)

Nu

mb

er

of

To

tal F

las

he

s

0

500

1000

1500

2000

0 400 800 1200 1600

Maximum -52 °C Cloud Shield Growth Rate (km2 min-1)N

um

be

r o

f C

G F

las

he

s

Total Lightning Evolution Total Lightning Evolution Relative to Cloud Shield Area Relative to Cloud Shield Area

for 27 May 2008 MCSfor 27 May 2008 MCS

0

40000

80000

120000

400 600 800

Time (UTC)

Are

a o

f -5

2 °C

Clo

ud

Sh

ield

(km

2 )

0

2000

4000

6000

Nu

mb

er o

f F

lash

es

0

10000

20000

30000

40000

400 500 600 700 800

Time (UTC)

Are

a o

f -6

0 °C

Clo

ud

Sh

ield

(km

2 )

0

2000

4000

6000

Nu

mb

er o

f F

lash

es

0

400

800

1200

400 500 600 700 800

Time (UTC)

Are

a o

f -7

2 °C

Clo

ud

Sh

ield

(km

2 )

0

2000

4000

6000

Nu

mb

er o

f F

lash

es

-52 ˚C -60 ˚C

-72 ˚C

Time series of total lightning shown in red, with cloud shield area shown in black

Total Lightning Evolution Total Lightning Evolution Relative to Cloud Shield Area Relative to Cloud Shield Area

and Minimum Cloud Top and Minimum Cloud Top Temperature for 1 July 2004 Temperature for 1 July 2004

MCSMCS

0

20000

40000

60000

80000

100 300 500 700 900 1100 1300

Time (UTC)

-52

°C C

lou

d S

hie

ld A

rea

(km

2 )

0

1500

3000

4500

Nu

mb

er o

f F

lash

es

0

1000

2000

3000

100 300 500 700 900 1100 1300

Time (UTC)

-60

°C

Clo

ud

Sh

ield

Are

a

(km

2 )

0

1500

3000

4500

Nu

mb

er o

f F

lash

es

-70

-65

-60

-55

-50

-45

100 300 500 700 900 1100 1300

Time (UTC)

Clo

ud

Sh

ield

T

emp

erat

ure

(°C

)

0

1500

3000

4500

Nu

mb

er o

f F

lash

es

-52 ˚C -60 ˚C

-60 ˚C

Minimum Brightness Temperature

Time Series of total lightning shown in red, with time series of cloud shield area shown in black and minimum brightness temperature shown in gray

Composite Time Series of Composite Time Series of Total Lightning Relative to Total Lightning Relative to

-52 and -66 ˚C Cloud -52 and -66 ˚C Cloud Shield Area Shield Area

-52 ˚C Cloud Shield

0

0.4

0.8

1.2

-600 -400 -200 0 200 400 600

Time Relative to Peak in -52 ˚C Cloud Shield Area (min)

Per

cen

t o

f P

eak

0.0

0.4

0.8

1.2

-600 -400 -200 0 200 400 600

Time Relative to Peak in -66 ˚C Cloud Shield Area (min)

Per

cen

t o

f P

eak

-66 ˚C Cloud Shield

Total lightning evolution shown in red, with black line indicating cloud shield

evolution

SummarySummary CG and total lightning flash rates usually CG and total lightning flash rates usually

evolve similarly, but ground flash fraction evolve similarly, but ground flash fraction tends to increase as deep convection weakenstends to increase as deep convection weakens

Most lightning initiated within deep Most lightning initiated within deep convection; fewer flashes initiated within convection; fewer flashes initiated within stratiform precipitationstratiform precipitation

Timing of evolution of flash rates is most Timing of evolution of flash rates is most similar to timing of evolution of coldest cloud similar to timing of evolution of coldest cloud shieldshield

Flash initiations depict configuration of deep Flash initiations depict configuration of deep convection better than IR cloud shield -- convection better than IR cloud shield -- comparable to depiction by radar reflectivitycomparable to depiction by radar reflectivity

Total and CG Lightning Total and CG Lightning Histograms for 30 April Histograms for 30 April

2004 MCS2004 MCS

0

500

1000

1500

300 400 500 600 700

Time (UTC)

Nu

mb

er

of

To

tal F

las

he

s

0

40

80

120

160

Nu

mb

er

of

CG

Fla

sh

es

Total activity denoted by bars

CG activity denoted by solid line

Ground Flash Fraction for Ground Flash Fraction for 30 April 2004 MCS30 April 2004 MCS

0

0.2

0.4

0.6

0.8

1

300 400 500 600 700

Time (UTC)

Gro

un

d F

las

h F

rac

tio

n

Total Flash Rate vs. Total Flash Rate vs. Ground Flash PercentageGround Flash Percentage

0

200

400

600

800

0 20 40 60

Ground Flash Percentage

Ma

xim

um

To

tal F

las

h R

ate

(fp

m)

Ground Flash Fraction for Ground Flash Fraction for 19 August 2007 MCS19 August 2007 MCS

0

0.2

0.4

0.6

0.8

1

100 300 500 700 900 1100 1300 1500

Time (UTC)

Gro

un

d F

las

h F

rac

tio

n

Positive Ground Flash Positive Ground Flash Fraction for Fraction for

19 August 200719 August 2007

0

0.25

0.5

0.75

1

100 300 500 700 900 1100 1300 1500

Time (UTC)

Po

sit

ive

Gro

un

d F

las

h F

rac

tio

n