A tool for improved space weather predictions: the CME expansion speed. Max-Planck-Institut für Aeronomie Katlenburg-Lindau Germany Instituto Nacional de Pesquisas Espacia Sao Jose dos Campos - SP Brazil A. Dal Lago , R. Schwenn Sept. , 2001
Jan 19, 2016
A tool for improved space weather predictions:the CME expansion speed.
Max-Planck-Institut für AeronomieKatlenburg-LindauGermany
Instituto Nacional de Pesquisas EspaciaisSao Jose dos Campos - SPBrazil
A. Dal Lago, R. Schwenn
Sept. , 2001
Space Weather
Geophysical Research Letters / 15 July 1998
Space Weather
Shock
Space Weather
-100
-50
0
Dst
(n
T)
0,00,10,20,30,4 static pressure
plus. rel. dyn. pressure
300
400
500
600
21201918
Oct., 1995
P (
nP
a)
V (
km/s
)N
(cm
-3)
T (
K)
Bz
(nT
)B
(n
T)
0204060
01x1052x1053x1054x1055x105
-20-10
01020
0
10
20
30
CLOUD
Shock
Sun:EIT / CME
Earth:geomagnetic storm
L1:shock - sheath - magnetic cloud
Coronal Mass Ejections - CME
Limb
Halo
LASCO C2 LASCO C3EIT 195 LASCO C2 LASCO C3EIT 195
Coronal Mass Ejections - CME
Limb CME
Halo CME
LASCO C2 LASCO C3
Acceleration/Deceleration of CMEsSept. 28, 1997
LASCO C2
Acceleration/Deceleration of CMEsSept. 28, 1997
LASCO C3
Acceleration/Deceleration of CMEsS85W
Acceleration/Deceleration of CMEsJuly 25, 1999
S85W
S75ES85E S70W S55W
LASCO C3
Halo CMEs from Jan. 1997 to Apr. 2001
Halo CMEs seen at the suntotal full partial
Front side 157 81 76Back side 41* 26* 15*Limb 23 4 19Not clear** 59 4 55total 280 115 165
* not all included** no (no unique) disk information available
Halo CMEs and Interplanetary association
Sun:EIT / CME
Earth:geomagnetic storm
L1:shock - sheath - magnetic cloud
Halo CME and Interplanetary associationtotal Clear IP
association*Possible IPassociation**
No IPassociation
full 81 50 27 4Front sidepartial 76 42 15 19full 4 3 0 1Limbpartial 19 7 6 6
totals 180 102 48 30* unique and clear CME-Interplanetary association** CME-Interplanetary association is not unique or not sure, but not discarded
Interplanetary signatures and CME association
Sun:EIT / CME
Earth:geomagnetic storm
L1:shock - sheath - magnetic cloud
Interplanetary signatures and its possible causestotal Clear
associationwith CME
Possibleassociationwith CME
Associationwith CIR
No association
Cloud or blob 35 15 19 0 1shock 148 87 47 2 12other 6 - - 6 -
Halo CMEs and geomagnetic storms
Sun:EIT / CME
Earth:geomagnetic storm
L1:shock - sheath - magnetic cloud
Intensity of the storm (Dst) total Caused by CIR Related to CMEs Not related-50 > Dst > -100 nT 84 6 74 4-100 > Dst > -200 nT 32 2 29 1 (Oct 28th 2000)Dst < -200 nT 8 0 8 0
CME expansion speed
Vexp
Vexp VexpVrad
Vpr Vpr
LASCO C3 LASCO C3 LASCO C3
Vexp
Vrad
Limb CMEs
57 events from 1997 to 2001Criterion: EIT 195 activity closeto the limb (maximum 30 deg.).
0 500 1000 1500 2000200
400
600
800
1000
1200
1400
1600
1800
2000 less than 40 deg. between 40 and 80 deg. more than 80 deg.
29.08.0157 limb events from 1997 to 2001 (not all!)
linear fit: Vr = 0.87919973 * VexpR = 0.85581399 ; SD = 132.94159
expansion speed (km/s)
radi
al s
peed
(km
/s)
Halo CMEs
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
140
front side halos limb CMEs
10.09.200194 measured points, 102 total, unique CME-IP association
trav
el ti
me
(h)
halo expansion speed (km/s)
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
14095 events, 102 total, unique CME-IP association
trav
el t
ime
(h)
halo front speed (km/s)
Frontal speed x travel time Expansion speed x travel time
Vexp
VprVfr
Halo CMEs
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
140
94 measured points, 102 total, unique CME-IP associationcurve fit: t = -22.75*ln(Vexp) + 220.8R = -0.62 ; SD = 14.61
limb events
03.09.2001
trav
el t
ime
(h)
halo expansion speed (km/s)0 500 1000 1500 2000 2500 3000 3500
0
20
40
60
80
100
120
140
95 events, 102 total, unique CME-IP associationcurve fit: t = -17.85*ln(Vfr) + 181.71R = -0.47 ; SD = 16.21
trav
el t
ime
(h)
halo front speed (km/s)
Frontal speed x travel time Expansion speed x travel time
Vexp
VprVfr
Full halos only
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
140 full halos only travel time at constant speed fitted curve dv/vt = -A*v
03.09.2001
53 measured points, 54 total, unique full halo-IP associationcurve fit: t = -22.85*ln(Vexp)+220.2R = -0.65, SD = 13.0
trav
el ti
me
(h)
halo expansion speed (km/s)
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
140 full halos only travel time at constant speed fitted curve dv/vt = -A*v
03.09.2001
53 measured points, 54 total, unique full halo-IP associationcurve fit: t = -22.85*ln(Vexp)+220.2R = -0.65, SD = 13.0
trav
el t
ime
(h)
halo expansion speed (km/s)
Ago. 25th 2001
Ago. 25th 2001
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
140 full halos only travel time at constant speed fitted curve dv/vt = -A*v
03.09.2001
53 measured points, 54 total, unique full halo-IP associationcurve fit: t = -22.85*ln(Vexp)+220.2R = -0.65, SD = 13.0
tra
vel t
ime
(h)
halo expansion speed (km/s)
Ago. 25th 2001
LASCO C2 LASCO C3EIT 195
Solwind CMEs and Helios 1
Solwind coronagraph
Helios 1+ 32 degr.
Period: 1979 - 198256 events - 45 where Vcme and Vip were possible to be obtained.
0 500 1000 1500 2000 2500 3000 35000
20
40
60
80
100
120
140
94 measured points, 102 total, unique CME-IP associationcurve fit: t = -22.75*ln(Vexp) + 220.8R = -0.62 ; SD = 14.61
limb events Helios CMEs
05.09.2001
trav
el ti
me
(h)
halo expansion speed (km/s)
Solwind and Helios 1
Vexp
Vcme
Helios1
•Solwind: Vcme Vexp•Solwind + Helios: travel time - avg. propagation speed - travel time to 1 AU
1 AU
Expansion speed x shock speed at 1AU
0 500 1000 1500 2000 2500 3000 3500
300
400
500
600
700
800
900
1000
80 measured points, 88 total, unique halo-shock association
03.09.2001
sh
ock
sp
ee
d (
km/s
)
halo expansion speed (km/s)
200 400 600 800 1000 1200 1400 1600200
300
400
500
600
700
800
900
1000
1100
limb events
88 measured points, ?? total, unique halo-shock associationlin fit: Vsh = 0.43*Vpr + 254.97R = 0.67, SD = 106.02 03.09.2001
shoc
k sp
eed
(km
/s)
propagation speed (km/s)
Propagation speed x shock speed at 1AU
Conclusions
• Limb CMEs show a linear relation between Vexp and Vrad• There is a good correlation found between the expansion speed (Vexp) of halo CMEs and the travel time to 1 AU.• The halo expansion speed (Vexp) can now be used to predict thetravel time of CMEs.• There is still substantial uncertainty, indicating that processes occurring during the “trip” of the CMEs from the sun to 1 AU may play an important whole.• 4 out of 81 full front side halo CMEs never reachead the earth - false alarms!• 12 out of 146 transient IP shocks were not related to any CME - prediction missed!• 1 out of 30 intense storms and 4 out of 78 moderate stormswere not related to any CME - storm prediction missed!• All very intense (Dst<-200 nT) were related to halo CMEs.