TLE Corte June 2008 BALLOON BORNE DC AND AC ELECTRIC MEASUREMENTS IN THE VICINTY OF TROPICAL...
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Transcript of TLE Corte June 2008 BALLOON BORNE DC AND AC ELECTRIC MEASUREMENTS IN THE VICINTY OF TROPICAL...
TLE Corte June 2008
BALLOON BORNE DC AND AC ELECTRIC MEASUREMENTSIN THE VICINTY OF TROPICAL CONVECTIVE CLOUDS.
J.J. BERTHELIER 1, F. SIMOES 1, J.P. POMMEREAU 2
1 CETP/IPSL, 2 SERVICE D’AÉRONOMIE/IPSL
TLE Corte June 2008
Overview of the presentation
1- Objectives and description of the HV-AIRS experiment
2- Meteorological conditions during flight
3- Global parameters of atmospheric electricity, EDC and σ
4- Small scale features and electric turbulence in clouds
5- Lightning and atmospheric electric fields- Lightning detection- EDC and EAC variations associated with lightning
6- Summary and conclusions
TLE Corte June 2008
HV-AIRS, Instrumentation
Double-Probe Electric Field Instrument
Vertical component of Electric Field, DC to 4 kHz - Large signal « DC channel » DC to 2 kHz from ~ ± 50 mV/m to ± 200 V/m(up to ± 10 kV/m in special mode)- Small signal « AC channel » 4 Hz to 4 kHz noise level ~ 30 µV/m. Hz1/2
Conductivity measurements relaxation method
Optical sensors
- lightning detectors upward and downard fast light detectors - ODS sensor (not used in this study)
Flight : August 7, 2006 16.45-20.00 UT from Niamey
TLE Corte June 2008
18.01 19.31 19.0118.31
HV-AIRS, Local meteorological conditions during flight
18 km
Balloon position
Courtesy E. Williams, MIT
20.01
TLE Corte June 2008
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000-8000
-6000
-4000
-2000
0
2000
4000
Time [s]
Ele
ctric
Fie
ld [1
]
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000
5
10
15
20
25
Alti
tude
[km
]
DC Field 1
DC Field 2
DC1-DC2
HVAIRS DC Electric Field
E ~ - 2.5 V/m
Conductivity at ceiling altitudes
- ~ 310-13 Sm-1+ ~ 210-13 Sm-1
Ceiling altitude ~ 22.5 km Sunset at balloon altitude
DC2 lower electrode
DC1 upper electrode
Max E -25V/m at 6 km
EDC = DC1 – DC2
TLE Corte June 2008
5 10 15 20 25 30 35
1
2
3
4
5
6
7
8
9
10x 10
6
Fréquence [Hz]
ampl
itude
du c
ham
p
Intégration des FFT de chaque page des fichiers 4 à 12 (divion 15)
fichier4
fichier5fichier6
fichier7
fichier8
fichier9
fichier10fichier11
fichier12
Power (au)
HVAIRS_AMMA AC ELECTRIC FIELDSBackground noise during ascent and Schumann resonnances
0 5 10 15 20 25 30 35 400
0.5
1
1.5
2
2.5x 10
6
Fréquence [Hz]
Am
plit
ude d
u c
ham
p
Intégration des fft de chaque page des fichiers 12 à 21 (division 15)
fichier12fichier13
fichier14
fichier15
fichier16fichier17
fichier18
fichier19
fichier20fichier21
Ascent 0- 20 km
Ascent 20 – 22.5 kmand ceiling
8
1420 26.5 32.5 38.5
TLE Corte June 2008
700 800 900 1000 1100 1200 1300 1400 1500 16000
5
10
15
20
25
Integrated power in the range 0-20 Hz
Alti
tude
[km
]
AC Power SpectrumFiltered SpectrumAerosols concentration
HV-AIRS AMMA AC Electric Field power intensity in the frequency range 0-20Hz
and aerosol layers
TLE Corte June 2008
0 50 100 150 200 250 300 350-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Time [s]
AC
Fie
ld [V
m-1
]
File 8
0 50 100 150 200 250 300 350
15
20
25
T0=17:24:49 + Time [s]
DC
Fie
ld [V
m-1
]
0 50 100 150 200 250 300 35011.5
12
12.5
13
13.5
14
14.5
Alti
tude
[km
]
1
12 km 13.5 km0 50 100 150 200 250 300 350-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Time [s]
AC
Fie
ld [
Vm-1
]
File 9
0 50 100 150 200 250 300 350
6
8
10
12
T0=17:31:13 + Time [s]
DC
Fie
ld [
Vm-1
]
0 50 100 150 200 250 300 35014
14.5
15
15.5
16
16.5
Altitude [
km
]
14.2 km
15 km
0 50 100 150 200 250 300 350-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Time [s]
AC
Fie
ld [
Vm
-1]
File 10
0 50 100 150 200 250 300 350
5
10
T0=17:37:37 + Time [s]
DC
Fie
ld [
Vm
-1]
0 50 100 150 200 250 300 35016.5
17
17.5
18
18.5
19
Alti
tude
[km
]
2
17 km
18.3 km
16.2 km
3 and 4
3
HV-AIRS AMMA Quasi DC Electric Field ULF signatures and aerosol layers
TLE Corte June 2008
HV-AIRS AMMA : aerosol profile above 10 km
1 12.5 km
2 15 km
4 18.4 km
5 20 km
6 21.2 km
3 16.8 km
Courtesy G. Di Donfrancesco, ENEA
Aerosol Backcattering, AU
TLE Corte June 2008
H = 30 m ~ 1 V m-1
HVAIRS_AMMA Quasi-DC Electric FieldsModeling ULF signatures associated with clouds
L
Balloon ascent
Δt ~ 50 s
Time and Altitude
Electric field
Δt ~ 6sH ~ 30m
Charged layer
L
TLE Corte June 2008
L = 50 m, H = 30 m, uniform charge density RedL = 50 m, H = 30 m, charge density ~ exp(- z2/2h2) h = H/3 Green L = 100 m, H = 30 m, uniform charge density Blue L = 100 m, H = 30 m, charge density ~ exp(- z2/2h2) h = H/3 Black
3002001000 -100 -200 -300 -0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
Distance [m]
Ele
ctric
Fie
ld [V
m-1
]
Ascent through the center of the volume
Q total ~ + 1.5 µCFor ΔE ~ 0.06 V/m
TLE Corte June 2008
HVAIRS, CHARGED CIRRUS ABOVE THE TROPOPAUSEIMPLICATIONS FOR STRATOSPHERIC WATER
- Electrically charged layers detected above the tropopause (~16.5 to 18 km) horizontal dimensions ~ 40 m, thickness ~ 30 m, total average charge ~+50 µC- Geophysica flight data (courtesy de Reus, MPI Mainz) within ~ 1-2 days Aerosols with average density ~ 0.01/cm3 and effective radius 2-14 µm
- Charged layers identified as stratospheric cirrus with charged ice particles
Charged volume ~ 5 1010 cm3, Number of particles ~ 5 108
Charge on individual ice particles: ~ 10-13 C
- Electric Field above active thunderstorms: 1 to 10 kV/m
- Electric Force: Fe = qE ~ 10-10 to 10-9 N
- Atmospheric drag force: Re < 1 thus Fa ~ 6π.µ.r.V (assuming spheres)
diameter 10 µm Fa ~10-9 N for V ~1 m/s Fa ~ 10-8N for V ~10 m/s
diameter 1 µm Fa ~10-10 N for V ~1 m/s Fa ~ 10-9N for V ~10 m/s
For small (< 1µ) particles, electric force > vertical updraft force
Upward transport of water to stratosphere above thunderstorms
Atmospheric E-field as efficient as vertical winds for small ice particles
TLE Corte June 2008
6.9 6.95 7 7.05 7.1 7.15 7.2 7.25 7.3 7.35 7.40.9
1
1.1
1.2
1.3
1.4
1.5
1.6
DC
Fie
ld [
Vm
-1]
File:28 Pages:4-4
6.9 6.95 7 7.05 7.1 7.15 7.2 7.25 7.3 7.35 7.40
1
2
3
4
5
Time [s]
Ligh
tnin
g [1
]
precursors Continuing current
HV-AIRS LIGHTNING and E-FIELD ΔE > 0
Precursors and Continuing currents
TLE Corte June 2008
HV-AIRS LIGHTNING and E-FIELDPrecursors and Continuing Currents
Precursors Continuing current
TLE Corte June 2008
21 21.1 21.2 21.3 21.4 21.5 21.6 21.7 21.8 21.9 22
0.6
0.8
1
1.2
1.4
1.6
DC
Fie
ld [
Vm
-1]
File:29 Pages:2-2
21 21.1 21.2 21.3 21.4 21.5 21.6 21.7 21.8 21.9 220
1
2
3
4
5
Time [s]
Ligh
tnin
g [1
]
HV-AIRS LIGHTNING and E-FIELD
Δ E > 0
TLE Corte June 2008
14 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 15-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
DC
Fie
ld [
Vm
-1]
File:29 Pages:5-5
14 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 150
1
2
3
4
5
Time [s]
Ligh
tnin
g [1
]
HV-AIRS LIGHTNING and E-FIELD
Δ E > 0
TLE Corte June 2008
5.55 5.6 5.65 5.7
-0.4
-0.2
0
0.2
AC
Fie
ld [
Vm
-1]
File:28 Pages:9-9
5.55 5.6 5.65 5.70
0.5
1
DC
Fie
ld [
Vm
-1]
5.55 5.6 5.65 5.70
1
2
3
4
5
Time [s]
Ligh
tnin
g [1
]
HV-AIRS LIGHTNING and E-FIELD
Δ E > 0
TLE Corte June 2008
20 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 21-0.2
0
0.2
0.4
0.6
0.8
AC
Fie
ld [
Vm
-1]
File:25 Pages:7-7
20 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 210.8
0.9
1
1.1
DC
Fie
ld [
Vm
-1]
20 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 210
1
2
3
4
5
Time [s]
Lig
htn
ing [
1]
E AC
E DC
Lightning
HV-AIRS AMMA, LIGHTNING, EM Pulse and Transverse resonance
Freqency ~ 2 kHz
TLE Corte June 2008
0 5 10 15 20 251900
1950
2000
2050
2100
2150
2200
2250
Time - nonlinear scale [1]
Fre
qu
en
cy [H
z]
Transverse Resonance: frequency variation during flight
TLE Corte June 2008
HV-AIRS LIGHTNING AND ELECTRIC FIELDSSUMMARY
AC ELECTRIC FIELDS
- EM pulse followed by oscillations at frequency ~ 2 kHz, Transverse Resonance
Quasi DC ELECTRIC FIELDS- Main Lightning: Step-like variation of the vertical electric field
- average ampltude ~ 0.1-0.2 V/m- rise time ~ 5 to 10 ms,- recovery time: exponential decay with time constant ~ 0.5 s
- Precursors and Continuing Currents: similar or larger effects- Comparison with Rycroft et al. (JASTP 2007) model
- ΔE > 0 : negative CG lightning, almost all cases- ΔE < 0 : positive CG lightning, a few cases- ΔE = 0 : IC or CC lightning (?)- [recovery time] / [rise time] ~ 20 to 40- measured amplitudes > 100 model amplitudes- measured rise and recovery times ~ 10-3 model times
- Small scale processes vs global model ?- Resistive Ionosphere?