Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space...
-
Upload
norman-bell -
Category
Documents
-
view
219 -
download
0
Transcript of Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space...
![Page 1: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/1.jpg)
Morphology of Inner Magnetospheric
low-energy ions
M. Yamauchi, et al.
Swedish Institute of Space Physics (IRF), Kiruna
![Page 2: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/2.jpg)
Ion drift under strong B-field (e.g. inner magnetosphere)
Magnetic drift (Energy dependent)
* gradient-B drift
* curvature drift
⇒ dominant for > 10 keV
ExB drift (Energy independent)
* co-roration E-field
* external E-field
⇒ dominant for < 0.1 keV
![Page 3: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/3.jpg)
Ion drift
Energy dependent for magnetic drift and Energy independent for ExB drift/corotation
external E-field
![Page 4: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/4.jpg)
Ion drift
Westward drift for high energy/evening and Eastward drift for low-energy/morning
![Page 5: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/5.jpg)
Ion drift
Variation in the source and E-field makes the ion population a zoo of various patterns
![Page 6: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/6.jpg)
Characteristic of Cluster Perigee
* North-South symmetric
* Quick scan of all latitude
![Page 7: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/7.jpg)
![Page 8: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/8.jpg)
The examined ion signatures (1)
(b) Wedge-like energy-latitude dispersed ions at sub-keV range: predominantly found in the morning sector some hours after a substorm. The source population is much colder than the plasma sheet. (both symmetric/asymmetric)
(e) Internal asymmetry of (b)
![Page 9: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/9.jpg)
(c) Vertical stripes: similar to the wedge-like structure but dispersion is weak (nearly vertical in the spectrogram). The energy extends from the about 10 keV to sub-keV. (both symmetric/asymmetric)
The examined ion signatures (2)
![Page 10: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/10.jpg)
The examined ion signatures (3)
(d) Short bursts of low-energy ions isolated from the above structures: a peak energy flux less than 100 eV but not thermal. (both symmetric/asymmetric)
![Page 11: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/11.jpg)
The examined ion signatures (4)
(f) Warm trapped ions confined near equator: ~ tens eV to a few hundred eV.
![Page 12: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/12.jpg)
(b) Wedge-like energy-latitude dispersed ions at sub-keV range: predominantly found in the morning sector some hours after a substorm. The source population is much colder than the plasma sheet.
(c) Vertical stripes: similar to the wedge-like structure but dispersion is weak (nearly vertical in the spectrogram). The energy extends from the about 10 keV to sub-keV.
(d) Short bursts of low-energy ions isolated from the above structures: a peak energy flux less than 100 eV but not thermal.
(e) Internal asymmetry of (b)
(f) Warm trapped ions confined near equator: tens eV to a few hundred eV.
The examined ion signatures (1)-(4)
![Page 13: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/13.jpg)
![Page 14: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/14.jpg)
Characteristic of Cluster Perigee
* North-South symmetric
* Quick scan of all latitude
+north-south symmetric nature of trapped ions (due to bouncing) Distribution must be north-south symmetric
![Page 15: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/15.jpg)
Where? Inner Magnetosphere at 4~6 RE (Cluster perigee)
Species? H+ of 10 eV ~ 10 keV (CIS/CODIF energy range)
Distribution? Intense ion population (except plasma sheet)
In this work: (a) Statistics distribution, (b) 1-2 hour scale evolution/decay (using inbound-outbound asymmetry), (c) relation to substorms (using elapsed time from high AE),(d) modeling (using Ebihara’s simulation code).
We examined all SC-4 perigee pass during 2001-2006 (about 670 traversals, with relatively clean data of 460 traversals).
Analyses
![Page 16: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/16.jpg)
Before analyses, we have to examine possible “biases” such as Instrument Degradation or Solar Cycle phase
Database quality check
We examine both “inbound-outbound” symmetric & asymmetric cases
![Page 17: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/17.jpg)
Decrease of “wedge-like” is not due to solar cycle !
Occurrence of substorm is rather constant
![Page 18: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/18.jpg)
The same for “low-energy burst”
Occurrence of substorm is rather constant
![Page 19: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/19.jpg)
But “vertical stripes” show some solar cycle effect
![Page 20: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/20.jpg)
Rather, the decrease is due to instrumental effect
Rapid degradation of the sensor
Occurrence of substorm is rather constant
![Page 21: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/21.jpg)
Impossible to take statistics during 2003-2004 because of radiation dose. Otherwise large decrease.
How about warmed trapped ions?
Rapid degradation of the sensor
Occurrence of substorm is rather constant
![Page 22: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/22.jpg)
(1) Both 2001-2003 & 2004-2006 show morning peak We can safely use 2001-2006 data together.(2) Very high observation frequency in the morning (> 80%)
Next check:Is Local Time distribution affected by this bias?
![Page 23: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/23.jpg)
![Page 24: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/24.jpg)
Local Time distributionsy
mm
etric
+ a
sym
met
ric
enha
nced
with
in tr
aver
salWedge-like:
high-occurrence (morning) peak is not midnight enhance > symmetric > decay
Vertical stripe: midnight phenomena enhance (midnight) decay ~ enhance (other LT)
Low-energy burst: all local time enhance ~ decay time scale ~ 1 hour
enhance/decay factor 3 change
![Page 25: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/25.jpg)
Is enhancement related to substorm?
AL
AU
AL
AU
![Page 26: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/26.jpg)
eastward drift
Viking 14 MLT
poleward
6 MLT
9 MLT
12 MLT
15 MLT
18 MLT
For the wedge-like dispersion, the relation to substorm has already been studied:
After AE>400 nT activity,
(1) Moves eastward
(2) Decay in time
hr from substorm
cf. Viking
![Page 27: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/27.jpg)
Rel
atio
n to
AE
act
iviti
es
Loc
al T
ime
dist
ribut
ion
* Strong preference during |AL|>300 nT activity* Outstanding at midnight Related to substorm-related injction * Optimum at 300 nT threshold (cf. 200, 400 nT)
Vertical stripes
![Page 28: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/28.jpg)
Rel
atio
n to
AE
act
iviti
es
Loc
al T
ime
dist
ribut
ion
* Same result as Viking (morning~0h, afternoon>5h)* Less enhancement with elapsed time stagnation* Yet, enhancements after 5h & aftrnoon ???
Wedge-like dispersion
![Page 29: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/29.jpg)
Rel
atio
n to
AE
act
iviti
es
Loc
al T
ime
dist
ribut
ion
* slight decrease of “change” with time* but stagnation
Low-energy burst
![Page 30: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/30.jpg)
The inner magnetospheric low-energy ion populations (1)-(3) below show significant changes within 1-2 hours.
(1) Wedge-like energy-latitude dispersed ions (< a few keV),
(2) Vertical stripes (< 10 keV),
(3) Short-lived low-energy ion burst (< few hundred eV).
• For all three patterns, asymmetric cases (large inbound-outbound difference) are found more often than symmetric cases at almost all LT.
• For vertical stripes, majority of local midnight pass show large inbound-outbound difference when AL<300 nT.
• For low-energy burst, the lifetime is estimated as short as 1 hour
Summary 1
![Page 31: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/31.jpg)
Where? Inner Magnetosphere at 4~6 RE (Cluster perigee)
Species? H+ of 10 eV ~ 10 keV (CIS/CODIF energy range)
Distribution? Intense ion population (except plasma sheet)
In this work: (a) Statistics distribution, (b) 1-2 hour scale evolution/decay (using inbound-outbound asymmetry), (c) relation to substorms (using elapsed time from high AE),(d) modeling (using Ebihara’s simulation code).
We examined all SC-4 perigee pass during 2001-2006 (about 670 traversals, with relatively clean data of 460 traversals).
Next
![Page 32: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/32.jpg)
Rel
atio
n to
AE
act
iviti
es
Loc
al T
ime
dist
ribut
ion
* Same result as Viking (morning~0h, afternoon>5h)* Less enhancement with elapsed time stagnation* Yet, enhancements after 5h & aftrnoon ???
Wedge-like dispersion
![Page 33: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/33.jpg)
Why inbound-outbound difference of “wedge” at Noon-Afternoon sector so often?
⇒ We examine using numerical simulation (Ebihara’s code)
![Page 34: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/34.jpg)
The ion drift alone can re-produce significant inbound-outbound difference !
0.1 keV
t ≈ 15 hr
![Page 35: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/35.jpg)
Another example: sub-keV (dispersion asymmetry) and a few keV (ion band)
0.1 keV
t ≈ 6 hr
t ≈ 4 hr
![Page 36: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/36.jpg)
The significant changes of the “ Wedge-like dispersed sub-keV ions within only 1-2 hours can be explained by the drift motion even in the noon-afternoon sector.
But some signatures are yet naturally explained by the local inflow from ionosphere, that also has short time scale.
For both sources, the ion energy is very low (< 0.1 keV) but not cold.
Summary 2
![Page 37: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/37.jpg)
Future work: * Mass dependence* Pitch-angle dependence
![Page 38: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/38.jpg)
note: // >> does not necessarily mean ⊥ionospheric source but mirroring ions
![Page 39: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/39.jpg)
Next
![Page 40: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/40.jpg)
equator
Confined near equator = Only direction
spin axis
12
4
5
78S
C m
otion
sectors ≈ PA
E(H+) << E(He+) : new
![Page 41: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/41.jpg)
equator
equator
equator
All Local time
All AE conditions
Energy-time dispersion = new
Appearing in 40 min = new!
statistics & dynamics
![Page 42: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/42.jpg)
Summary 3We also studied the “equatorially-trapped warm ions” which are basically symmetric between inbound and outbound
• The energy of He+ is often higher than that for H+.
• Some events show a non-thermal ring distribution rather than superthermal pancake distribution.
• Some events show energy-time dispersion, indicating drifts from different local times.
• The time scale of the development is again about 1 hour.
• At about 4-4.5 RE, the observation probability is about 1/3 (night-dawn) to 1/2 (noon-dusk).
• The He+/H+ ratio is variable and is much less than 5% for the majority of the cases.
![Page 43: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/43.jpg)
Future work:
(2) (n+(1/2))fce wave is accompanied
* relation to wave
![Page 44: Morphology of Inner Magnetospheric low-energy ions M. Yamauchi, et al. Swedish Institute of Space Physics (IRF), Kiruna.](https://reader035.fdocuments.in/reader035/viewer/2022062322/56649e9e5503460f94b9f739/html5/thumbnails/44.jpg)
Future work: * relation to wave* compare different SC