Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere
description
Transcript of Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere
![Page 1: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/1.jpg)
Inner Magnetospheric Shielding, Penetration Electric Field, and the
Plasmasphere
GEM (Student) Tutorial June 23, 2002
Jerry Goldstein, Rice University
1
![Page 2: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/2.jpg)
The Plasmasphere
D. L. Carpenter (Stanford)“Whistler” wave studies
(ground-based)
Chappell et al., OGO data
Plasmapause: boundary where dense,
cold plasma ends M-I Coupling: WG-1+2:Ionospheric outflow
Wednesday 10:30-noonChairs: Lotko, Moore, Peterson
Ionospheric outflow: Populates p’sphere
2
![Page 3: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/3.jpg)
Magnetospheric Convection1. Generally sunward in the inner magnetosphere2. Southward IMF
3
![Page 4: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/4.jpg)
Magnetospheric ConvectionExplain sharp ppause:
Boundary between corotation (refilling) and
convection
4
![Page 5: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/5.jpg)
Magnetospheric ConvectionPlasmapause:
Density gradient marking outer boundary of plasmasphere--
does not need to coincide with the instantaneous boundary between
convection and co-rotation, because time scale for p’sphere response is slower than
time scale of convection variations.
M-I Coupling: WG-2:M’spheric convectionTuesday 3:30-5:30pmChair: Ray Greenwald
WARNING: This is a highly oversimplified picture!In reality, convection is
usually very nonuniform and time-dependent
Plasmapause
Conv/corot boundary
5
![Page 6: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/6.jpg)
IMAGE Extreme Ultraviolet Imager (EUV)
REMOTE MEASUREMENTThe Extreme Ultraviolet (EUV) imager
looks at the plasmasphere via
EUV data 6:43-10:04, 5/24
QuickTime™ and a decompressor
are needed to see this picture.
MOVIE
6
![Page 7: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/7.jpg)
Measuring the Plasmasphere
IMAGE EUV
in situCross-Phase
(ground magnetometer)
IM/S: WG-1:Plasmaspheric structure
Monday 3:30-5:30pm (observations)Chair: Dennis Gallagher
Tuesday 10:30-noon (techniques)Chairs: Moldwin, Chi
7
![Page 8: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/8.jpg)
Plasma Tails (“Plumes”)
MI Coupling: WG-1:plasmaspheric tails (“plumes”)
Monday 10:40-noon Chair: Tom Moore
8
![Page 9: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/9.jpg)
The Duskside Bulge?
Plasma Tails
“Detached” plasma
9
![Page 10: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/10.jpg)
Plasma Tails
Space Weather Implications...
As Seen in the Ionosphere
10
![Page 11: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/11.jpg)
Shielding:the plasmasheet,
Westward currents
11
![Page 12: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/12.jpg)
Shielding:Convection increase
due to dawn-dusk E--> creates partial RC
12
![Page 13: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/13.jpg)
Shielding:Partial RC closes in ionosphere via field-
aligned currents
13
![Page 14: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/14.jpg)
Shielding:Field-aligned currents create zonal charging.
14
![Page 15: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/15.jpg)
Shielding:Zonal charging creates
potential drop across IM, creating dusk-dawn E that
opposes/cancels dawn-dusk convection E
15
![Page 16: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/16.jpg)
E-shielding exactly cancels E-convection
IM ShieldingInstead of this...
You get this...
16
![Page 17: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/17.jpg)
E-shielding exactly cancels E-convection
IM Shielding
Shielding: 15 min - 1 hrThus, changes in Solar-wind/IMF conditions that occur more rapidly than the shielding time-scale allow convection field to penetrate past the shielding layer.
Perfect shielding might not occur even if conditions are steady, however. (See Dick Wolf’s tutorial.)
17
![Page 18: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/18.jpg)
E-shielding exactly cancels E-convection
E-conv UP:
Sunward IM
plasma flow
E-conv DOWN
Tailward IM
plasma flow
Penetration E-Fields 18
![Page 19: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/19.jpg)
E-shielding exactly cancels E-convection
E-conv UP:
Sunward IM
plasma flow
E-conv DOWN
Tailward IM
plasma flow
Penetration E-Fields 19
![Page 20: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/20.jpg)
E-shielding exactly cancels E-convection
E-conv UP:
Sunward IM
plasma flow
E-conv DOWN
Tailward IM
plasma flow
Penetration E-Fields 20
![Page 21: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/21.jpg)
Geomagnetic Variation of PlasmapauseSize/Shape of Plasmasphere
Depends on strength of convection
Well-Shielded
Swd IMF
Example: Plasmaspheric Erosion following sudden turn to southward IMF.
21
![Page 22: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/22.jpg)
Geomagnetic (Kp) Variation of Plasmapause
OGO 5 (in situ)
ISEE 1 (in situ)
22
![Page 23: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/23.jpg)
Geomagnetic Variation of Plasmapause
Aug 11, 2000: During/After Strong
Convection
July 9, 2000: Quiet
IMAGE EUV data
QuickTime™ and a decompressor
are needed to see this picture.QuickTime™ and a
decompressorare needed to see this picture.
23
![Page 24: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/24.jpg)
IM E-Fields
IM/S: Tutorial:I.M. E-fields
Monday 9:15-10amDick Wolf
IM/S: WG-1:Near-Earth E-fields
Monday 1:30-3pmChairs: Goldstein, Liemohn
24
![Page 25: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/25.jpg)
Simulated Penetration E-FieldsOvershielding: Shoulder
PDC
25
![Page 26: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/26.jpg)
Simulated Penetration E-FieldsOvershielding: Shoulder
Penetration E needed to explain shoulder
(and other meso-scale plasmaspheric
structure).
26
![Page 27: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/27.jpg)
IMAGE HENA27-39 keV
CRCM Model, 32 keV
Ring-Current and the IM E-field
IM/S: WG-1:RC/PS coupling (observations)
Tuesday 1:30-3pmChairs: C:son Brandt, Gallagher
RC/PS coupling (modeling)
Tuesday 3:30-5:30pmChairs: Liemohn, Reynolds
Penetration E needed to
explain observed
ring-current (RC)
distribution.
27
![Page 28: Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere](https://reader036.fdocuments.in/reader036/viewer/2022062501/56815db6550346895dcbe3ff/html5/thumbnails/28.jpg)
ConclusionsThe plasmasphere is the torus of cold, dense, co-rotating plasma surrounding the Earth out to 3-5 RE, and is populated by ionospheric outflow.
The plasmapause is the outer boundary of the plasmasphere, but does not need to coincide with the instantaneous boundary between convection and co-rotation (the “last closed equipotential” or LCE), because the time scale for plasmaspheric response is slower than the time scale of convection variations.
Plasmaspheric tails form during periods of high activity (Kp high, or Dst low), and extend all the way down to the ionosphere. (They can therefore affect Earth communications.)
The inner magnetosphere tries to shield itself from the convection E-fields, but the buildup of an effective shielding layer takes time. If the convection strength varies faster than the shielding time scale (somewhere between 15 minutes and an hour), E-fields can penetrate past the shielding layer, and into the inner magnetosphere.
Penetration E-fields can affect both plasmaspheric populations (forming meso-scale structure such as tails, shoulders and/or bite-outs), and ring current distributions.
28