total lightning activity as diagnostic for severe weather
DESCRIPTION
Total Lightning Activity as Diagnostic for Severe Weather. Earle R. Williams INPE Rio de Janerio, Brazil July 25-28, 2005. Outline. Experience with Thunderstorm Microbursts (Alabama, Florida; 1980s) Experience with Severe Weather (Florida; 1990s) - PowerPoint PPT PresentationTRANSCRIPT
MIT Lincoln Laboratory INPE Rio July 05
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Total Lightning Activity as Diagnostic for Severe Weather
Earle R. Williams
INPE Rio de Janerio, Brazil
July 25-28, 2005
MIT Lincoln Laboratory INPE Rio July 05
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Outline
• Experience with Thunderstorm Microbursts (Alabama, Florida; 1980s)
• Experience with Severe Weather(Florida; 1990s)
• Lightning and Severe Weather over the Continental U.S.(2000+)
MIT Lincoln Laboratory INPE Rio July 05
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Intracloud and Cloud-to-Ground Lightning:A Key Distinction
Cloud-to-GroundLightning
IntracloudLightning
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Behavior of Intracloud and Cloud-to-Ground Lightning
IC/C
G R
atio
105 Flashes/km2/15 min(Ground Flash Rate)
1.0
0.1
100
10
10 100 1000 10000
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Illustration of Microburst Hazardto Aircraft
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Microburst Accidents
Jun 24, 1975 EAL 66 JFK New York
Jun 23, 1976 AL 121 Philadelphia
Jun 03, 1977 CO 63 Tucson
Aug 22, 1979 EAL 693Atlanta (incident)
Jul 09, 1982 PAA 759 New Orleans
May 31, 1984 UA 663Denver (incident)
Aug 02, 1985 DL 191 DFW Dallas
Jul 02, 1994 US 1016 Charlotte
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National Response to Microburst Accidents
1. Regional field experiments to study the problem
Doppler radar measurementsSurface Mesonet arraysCorona point sensorsLightning interferometer system
2. Development and deployment of Terminal Doppler Weather Radars (TDWR)
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Microburst Field ExperimentsMIT Lincoln Laboratory
Huntsville, Alabama 1986 – 1987 C-band Doppler
and ASR-9 radars
Corona Part Array
Denver, Colorado 1987 – 1989 S-band DopplerMesonet
Corona Part Array
Kansas City, Missouri
1990 S-band Doppler
Mesonet
Orlando, Florida 1991 - 1993 Triple Doppler Network
Corona Part NetworkLightning Interferometer
Albuquerque, New Mexico
1994 – 1995 C-band Doppler and ASR-9 radarsLightning Interferometer
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Total Lightning Rate Precedes Microburst Outflow & Cloud-to-Ground Rate Does Not
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Distribution of Orlando Microburst Strength
(Orlando 1990 - 1992)
0
100
200
300
400
500
600
700
800
900
10-14 15-19 20-24 25-29 30-34 35-39 40-44 > = 45
DELTA V (m/s)
NU
MB
ER
OF
MIC
RO
BU
RS
TS
1990 (547, Radar was downfor an extended period)
1991 (1575)
1992 (1660)
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The LISDAD Project (1996 – 1999)
• Integration of multiple observations into one real-time system:
Lincoln Laboratory ITWS Melbourne NEXRAD radar Orlando TDWR radar National Lightning Detection Network Lightning Detection and Ranging System (NASA
KSC)
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Integrated Terminal Weather System (ITWS)
Microburst PredictionGust Front Prediction
Storm Location & MotionStorm Cell Information
Pilots
Controllers
AircraftLightning
ASR-9
LLWAS
ITWSReal-timeProcessor
AWOS/ASOS
TDWR NEXRAD
SupervisorsTraffic Managers – TRACON – ARTCC TMU
CWSUAirlines
– Dispatch– Ramp Tower
TornadoTerminal Winds
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What is ‘Severe’ Weather?
Formal thresholds in the U.S.
Hail diameter > ¾ inch
or, Wind speed > 50 knots
or, Tornado on the ground
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Fallspeed of Hail vs. Size
100
Par
ticl
e F
all S
pee
d (
m/s
ec)
50
20
10
5
2
1
Non-Severe Severe
Particle Diameter (mm)
1 2 5 10 20 50 100
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Updraft Strength is the Key Quality
• Supplier of super-cooled water
• Driver of cloud electrification and lightning
• Origin of hail growth and the thunderstorm ice factory
• Source of vortex stretching and tornado genesis
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Schematic Evolution of Total Lightning and Severe Weather
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Processes Aloft Naturally Precede Events at the Surface
• Accretion of supercooled water in updraft precedes arrival of large hail at the surface
• Active intracloud lightning aloft precedes cloud-to-ground lightning at the surface
• Mesocyclonic rotation aloft precedes the tornado at the surface
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22 May 1997Isolated Severe Storm1-inch HailOrlando, Florida
1-inch DiameterHail on Ground
0
50
100
150
200
250
300
350
Lig
htn
ing
(L
DA
R)
Fla
sh
Ra
te (
min
-1)
0
10
20
30
40
50
60
70
Dif
fere
nti
al
Ve
loc
ity
(k
no
ts)
Time (UT)
1810 19301830 19101850
Total Lightning Precursor to 1” Hailand Strong Outflow
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Histogram of Total LDAR flash rate
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Severe Storm Cases in LISDAD
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From Mesocyclone to Tornado
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Total Lightning Precursor to a Tornado
Goodman (2004)
LMA Flash trends Nov. 10-11, 2002 Cell e
0
5
10
15
20
25
23:49:30
23:54:29
23:59:29
0:04:28
0:09:27
0:15:31
0:20:30
0:25:32
0:30:31
0:35:30
0:40:29
0:45:29
0:50:28
UTC
Flash Rate/(5 minutes)
1 KM 2 KM 4 KM 8 KM F2 Tornado
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Global Lightning Based on the NASA LIS
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Dynamic Effect of Cloud Base Height on Updraft Intensity and Lightning Activity
Effect of cloud-base height on updraft width
Less dilution by mixing
High Cloud BaseLow Cloud Base
W
W
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Updraft Widths in Cumulonimbi
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Flash Rate / Thermodynamic Comparison
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Storm Flash Rate vs. Cloud Base Height
500 1000 1500 2000 2500 3000
0.81
2
4
6
810
20
40
Cloud Base Height, m
Total FR vs. CBH (Tropics,Jan-Jun 2000)Fl
ash
Rat
e, 1
/min
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Clustered Positive Ground Flashes in Severe Weather
Curran and Rust (1992)
Branick and Doswell (1992)
Seimon (1993)
Stolzenburg (1994)
MacGorman and Burgess (1994)
Knapp (1994)
Later work in STEPS (2000) provided strong evidence
that such storms were inverted in polarity relative to
ordinary thunderclouds.
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Important Advances in Steps in 2000
• Development and implementation of VHF lightning mapping techniques for identifying the polarity of the lightning ‘tree’ (New Mexico Tech)
• Inverted polarity storms characterized by large dew point depressions / low relative humidity
Rust and MacGorman (2002) Wiens et. al. (2003) Lang et. al. (2004)
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Laboratory Simulations Temperature / Cloud Water Diagrams
Takahashi (1978)
Saunders et al (1991)
Pereyra et al (2000)
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Microphysical Effect of Cloud Base Height onLiquid Water Content Aloft
Cloud water loss by coalescence
Superadiabatic loading in warm rain region
High Cloud BaseLow Cloud Base
0° C
W
W
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Extreme Weather in the Conus
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4” and Larger Hail Events(1955 – 1994)
(Polston, 1996)
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Climatology of Wet Bulb Potential Temperature (Noontime – July)
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Climatology of Cloud Base Height(Noontime – July)
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Inverted Polarity CloudsIs it Aerosol, or is it Hot, Dry Conditions?
(Lyons et al, 1998) (Smith et al, 2003)
May, 1998
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Conclusions
• Total lightning activity (dominated by intracloud lightning) is a natural precursor to microbursts and severe weather at the surface
• Cloud to ground lightning has relatively little benefit to this endeavor
• Recipe for inverted polarity and extraordinary total lightning activity: High cloud base height AND appreciable instability
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Slide left intentionally blank.
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Pre-Squall Line Soundings in Great Plains: CAPE vs. θw
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Storm Flash Rate vs. Dry Bulb Temperature
26 28 30 32 34 36 38 40
0.6
0.8
1
2
4
6
8
10
20
Maximum Dry Bulb Temperature, C
Total FR vs. DBT (Tropics,Jan-Jun 2000)Fl
ash
Rat
e, 1
/min
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Thermal Width/Updraft Width Scaling with Boundary Layer Depth?
OceanRH = 80%
Rondonia Wet SeasonRH = 70%
Rondonia PremonsoonRH = 60%
500 m
1000 m
1500 m
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The Role of Strong Instability in Promoting High Liquid Water Content
Large CapeStrong UpdraftBounded Weak Echo RegionVHF Radiation “Holes”
0° C
CapeW
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Cross-section of Dryline
Ziegler and Rasmussen, (1998)
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Delay of First NLDN Ground Flashfrom First LDAR Lightning in Storm
Nu
mb
er o
f O
bse
rvat
ion
s
Delay (min)
20
10
15
10
5
00 20 30 40 50 60
Mean Delay = 11 minutes
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Microburst Accidents Prompting Attention
• New Orleans, Louisiana – July 9, 1982
• Dallas / Ft. Worth, Texas – August 2, 1985
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Classic Microburst Image
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14 16 18 20 22 24 26 28 30
26
28
30
32
34
36
38
40
42
Dew Point Temperature, C
Dry
Bul
b T
empe
ratu
re, C
FR vs. Temperatures and CBH (Jan-Jun 2000)
Lightning Flash Rate vs Thermodynamics(Tropical Afternoon Storms Over Land)
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FAA Wind Shear Detection Systems