View
69
Download
0
Category
Tags:
Preview:
DESCRIPTION
Total Lightning Characteristics in Mesoscale Convective Systems. Don MacGorman NOAA/NSSL & Jeff Makowski OU School of Meteorology. Data Sources. Lightning Oklahoma Lightning Mapping Array (OK-LMA) National Lightning Detection Network (NLDN) - PowerPoint PPT Presentation
Citation preview
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
Recommended