[an error occurred while processing this directive] IRFU, Magnetopause

Magnetopause at small scales

Splinter session at the 3rd Cluster Workshop
Rutherford Appleton Laboratory, September 18-20, 2002

Co-chairs IRFU ( Stephan Buchert, Andris Vaivads), SSL (Stuart Bale, Forrest Mozer).

The idea of the session is to look at the magnetopause from small scales (electron gyroradius and electron inertial length) up to mesoscales (ion gyroradius and ion inertial length). The topics of interest could be the structure of the electron (if found) and ion diffusion regions, small scale current sheets, different waves (e.g. broadband, lower hybrid, whistlers) or solitary structures (e.g. electron holes) inside or close to the magnetopause.

We also briefly reviewed study results from the
Magnetopause splinter session from Cluster Workshop I.

Data plots

You are encouraged to present information on

  • Coverage (or lack thereof) for different instruments
  • Comments or plots of relevance for the intervals listed above, in particular for first priority events
  • Other intervals of interest

First priority events

DATE Data Comments
2002 Feb 06 [037]
0810-0815
0850-0900
(0948-0953)
Solar wind: Geotail
Cluster: 6h Quicklook orbit
EBspectra 0810-0815 0850-0900 0948-0953
CIS 07-10 0810-0815 0850-0900
EFW 0810-0815 0850-0900
FGM: 05-10 08-10
PEACE: text, C1234 LEAA 0800-1000
C3 spinpad 0810-0815 0850-0900 0948-0953
3D C4 0948-0953 C2 0854:10-0855:20 C4 0811:25-0812:35
STAFF 06-09
IMAGE: FUV
Page with more details on this event.

During several hours there are multiple crossings of MP and/or PS/BL. From those two intervals have been chosen within which there are also EFW internal burst data available.
1) EFW burst at 0812, outbound crossing of MP or PS/BL.
2) EFW burst at 0854 outbound crossing of MP or PS/BL, electron holes.

Similar ground track as 26 Feb, ground-based coverage.
Can be useful conjunction with Polar.
PEACE, CIS, WHISPER: pleased about burst mode

general sequence: lobe/mantle -> magnetosphere -> sheath

FGM: 8:12 UT v~80 km/s, current layer ~600 km
CIS: dispersed injection signatures, clear crossing into sheath, (magnetic field "strange"/complex)
STAFF: electric and magnetic wave activities not colocated
E waves more on the magnetosphere side
B waves more on the sheath side

FTEs around 8:46-8:55 UT

9:51:31 UT sheath FTE very close to MP
perhaps only reentry into boundary layer, not magnetosphere

WHISPER cannot tell difference between BL and magnetosphere

2002 Mar 02 [061]
0329-0334
Solar wind: ACE
Cluster: 6h Quicklook orbit
EBspectra: 0329-0334
CIS 03-04 0329-0334
EFW: 0329-0334
FGM: 00-05 0320-0355
PEACE: 03-05 0330-0332, spinpad 03-05, text
STAFF 03-06
WHISPER: 0315-0400 0329-0333
Single MP outbound crossing at 0331:08
Also in High altitude cusp session.

general sequence: cusp -> magnetosphere -> sheath
B increase before the crossing, dropout afterwards. V~35km/s and the thickness of current layer ~500km.

CIS: clear boundary layer present for ~ 2min

WHISPER: Langmuire waves, could be due to field-aligned low energy e- beams
Density versus position has been derived.
0329 precursor of MP inside magnetosphere. 
2002 Apr 02 [092]
0029-0033
SW: Wind ACE
Cluster: 6h Quicklook orbit
EBspectra 0029-0033
CIS 00-01 0029-0035
EFW: 0029-0033
FGM: 0014-0044
PEACE: 0029-0033 0030-0031, SPINPAD 01-02 0025-0035 text
STAFF 00-03
WBD: sp. 1t 1f 2t 2f
MP outbound crossing at 0031. EFW internal burst during the crossing, broad band waves, electron holes.
Also in High altitude cusp sessio  n.

CIS: very high velocity ~500 km/s, magnetic compression 00:30, also density jumps up

Lower priority events

2002 Mar 30
1311-1314
1328-1330
Solar wind: ACE Wind
Cluster: 6h Quicklook orbit
EBspectra: 1311-1314 1328-1330
CIS 13-14
EFW: 1311-1314 1328-1330
FGM: 13-14
IMAGE: FUV
MP outbound crossing ~1312UT and inbound crossing ~1313-1315UT.
EFW internal burst during the outbound crossing.
MP outbound crossing at 1328:40.

CIS ~1312 UT crossing without boundary layer

EDI: Integration of normal velocity gives distance to magnetopause
Very rapid entry into sheath, thin magnetopause, about 1 ion gyro radius
13:11 crossing into BL
13:28 crossing into magnetosphere
2002 Jan 11
0500-0750
Solar wind: ACE Geotail
Cluster: 6h Quicklook
CIS 0630-0750
EFW: 0500-0750
WBD: spectra
IMAGE: FUV
Large separation, multiple MP crossings for several hours.
WBD 0404-0615 s/c1.
2002 Feb 25
0822-0832
Solar wind: ACE
Cluster: 6h Quicklook orbit
EBspectra 0822-0832
CIS: 08-09
EFW: 0822-0832
FGM: 0530-1000 08-10 0810-0840
IMAGE: FUV
Inbound crossing between boundary layer and plasma sheet, ~0828.
|B| hole at ~0825:30.
Also in High altitude cusp session.

[A few minutes before interval there are EFW internal bursts in density gradients without current sheets (0813:06-16 s/c3, 0816:54-17:04 s/c 4).]

2002 Apr 18
1724-1732
Solar wind: ACE
Cluster: 6h Quicklook
EBspectra 1724-1734
CIS 17-18
EFW: 1724-1732
outbound crossing of magnetopause, can be cusp region.

Subjects to investigate in the near future

Subjects Investigators Comments
Thin sheets Andris, Mats High E fluctuations, current densities ~0.1 mA/m^2
sheet thickness ~10km, or a few electron gyro radii
Earthward Poynting flux
Field-aligned e- beams consistent with acceleration according potential difference
Ion and Electron diffusion regions Forrest, Stuart ion diffusion regions have a complex 3d structure even in a simple 2d Hall-MHD model
e- diffusion region: E not equal Ve x B, usually inside ion diffusion region
FTE structure near magnetopause Stephan, Malcolm Magnetic structure/topology, electric fields, ion and e- beams
Solitary structures Jolene

https://www.cluster.irfu.se/magnetopause/index.html
last modified on Monday, 03-Feb-2003 15:30:04 CET