# Presentation: 861672

## Electron observations in the magnetotail in response to a series of substorms:

** ****17-18 September 2003**
**J.A. Davies (J.A.Davies@rl.ac.uk), **
- M. Lockwood,M.W. Dunlop, C.H. Perry,
- I. Alexeev, M.G.G.T. Taylor, A.N. Fazakerley, C.J. Owen, A. Marchaudon, R.H.W. Friedel
- and P.W. Daly

**Notes:**
Title slide

## ACE5 UT, 17 September - 8 UT, 18 September 2003

**SWEPAM**

**MAG/GSM**

-  High speed (700 km/s) solar wind stream
-  Intervals of southward IMF up to 10 nT in magnitude
-  Results in particularly geoeffective solar wind conditions

**Notes:**
High speed solar wind stream preceded by a co-rotating interaction region

## Auroral Electrojet Indices17 September 2003 		18 September 2003

**DST****September 2003**

**Notes:**
DST shows that we are in the recovery phase of a minor storm
AE active substorm intervals

## LANL Geosynchronous Energetic Protons17 September 2003 		18 September 2003

**Notes:**
LANL electrons for the whole interval various enhancements and particle drop-outs observed

## LANL Geosynchronous Energetic Electrons17 September 2003 		18 September 2003

**Notes:**
LANL electrons for the whole interval various enhancements and particle drop-outs observed

## Cluster & Polar Orbits (GSE)5 UT, 17 September - 8 UT, 18 September 2003

-  Polar moves northward through the tail (twice during interval).
-  The thick lines indicate the interval used for more detailed 	study: 17 - 22 UT on 17 September 2003.

**Cluster & Polar Orbits (GSE)****5 UT, 17 September - 8 UT, 18 September 2003**

**Notes:**
Orbits (GSE) for interval – note that cluster is going north-south through the tail while Polar is going south-north, also note that during this interval Polar makes two traversals of the region to Cluster’s single pass.

## Cluster/RAPID-IES & -IIMS (spin-averaged flux)

**IES electrons****IIMS protons****IIMS H****e**** ions****IIMS C/N/O ions**

**Notes:**
Spin averaged energetic electron and ion flux – enhancements seen in both electrons and ions though some of the fine structure differs

## Polar/CEPPAD & Cluster/RAPID, PEACE and FGM

**CEPPAD-IES****RAPID-IES****PEACE-HEEA****FGM B-components****FGM B-magnitude**

**Notes:**
Combined plot of Polar energetic electrons and Cluster electrons and mag field for the full interval under investigation – note the high intensity bands seen in Polar correspond to the two dayside perigee passes during this interval.

## Polar/CEPPAD & Cluster/RAPID, PEACE and FGM

**Notes:**
Combined plot of Polar energetic electrons and Cluster electrons and mag field for the full interval under investigation – note the high intensity bands seen in Polar correspond to the two dayside perigee passes during this interval.

## Polar/CEPPAD & Cluster/RAPID and PEACE PADs

**Polar-IES: 50 keV****RAPID-IES: 50 keV****PEACE-HEEA: 10 keV****PEACE-HEEA: 5 keV****PEACE-HEEA: 2 keV**

**Polar/CEPPAD & Cluster/RAPID and PEACE PADs**

**Notes:**
Combined plot of Polar energetic electrons and Cluster electrons and mag field for the full interval under investigation – note the high intensity bands seen in Polar correspond to the two dayside perigee passes during this interval.

## Polar and Cluster Energetic Particle 

**Signatures: Timing Analysis**

| Time atPolar | Polar
Dipole L | Polar Dist from Model NS |  | Time at Cluster | Cluster
Dipole L | Cluster Dist from 
Model NS |
| --- | --- | --- | --- | --- | --- | --- |
| Polar at perigee |  |  |  | 06:20 | 17.8 | 5.93 |
| 10:10 | 18.1 |  | -5.28 | 09:20 | 16.4 | 3.09 |
| 12:25 | 15.7 |  | -5.67 | 11:10 | 16.6 | 1.22 |
| 14:30 | 14.3 |  | -5.21 | 14:00 | 18.2 | -1.36 |
| 17:52 | 10.5 |  | -2.73 | 18:20 | 20.8 | -3.82 |
| 20:50 | 7.6 |  | 0.38 | 21:55 | 20.9 | -4.74 |
| 02:45 | 27 |  | -3.85 | 02:40 | 20.6 | -6.35 |
| 05:50 | 11.4 |  | -4.35 | 06:30 | 22.2 | -8.67 |

**Notes:**
Cluster and Polar energetic particle signatures - timing

## Polar and Cluster 

- y = 3.9805x - 0.4845

- R

- 2

-  = 0.8284

- -6.00

- -4.00

- -2.00

- 0.00

- 2.00

- 4.00

- 6.00

- -1.500

- -1.000

- -0.500

- 0.000

- 0.500

- 1.000

- 1.500

**dT, hrs**

**dR (model NS), Re**

- Polar Closer to NS

- Cluster Closer to NS

**Polar and Cluster **
**Energetic Particle Signatures:**
**Timing Analysis**

**Notes:**
Cluster and Polar energetic particle signatures - timing

## Polar and Cluster 

- y = 6.2607x - 6.6326

- R

- 2

-  = 0.9196

- -15

- -10

- -5

- 0

- 5

- 10

- -1.500

- -1.000

- -0.500

- 0.000

- 0.500

- 1.000

- 1.500

**dt, hrs**

**dL**

- Polar Closer to NS

- Cluster Closer to NS

**Polar and Cluster **
**Energetic Particle Signatures:**
**Timing Analysis**

**Notes:**
Cluster and Polar energetic particle signatures - timing

## Ground-based Magnetometer: SAMNET

**Ground-based Magnetometer: SAMNET**
**17 - 22 UT on 17 September 2003**

-  Two energetic particle signatures can be identified in 	the spacecraft data during this interval.
-  Pi2 pulsations from SAMNET indicate corresponding 	substorm onsets at 17:35 (A) and 20:45 UT (B).

- A                         B                         A                         B                        A                          B

**Notes:**
SAMNET Pi-2 pulsations used to determine onset time for the two substorms

## LANL Geosynchronous Energetic Protons

**LANL Geosynchronous Energetic Protons**

**Notes:**
LANL proton data used to help confirm onset time

## LANL Geosynchronous Energetic Electrons

**LANL Geosynchronous Energetic Electrons**

**Notes:**
LANL electron data used to help confirm onset time

## Polar/CEPPAD & Cluster/RAPID, PEACE and FGM

- 17:35 UT

- 20:45 UT

**Polar/CEPPAD & Cluster/RAPID, PEACE and FGM**

**Notes:**
Polar and Cluster results particle and field for expanded period.
Note stalled magnetic field dipolarisation coincident with near earth injection of particles seen by Polar could this correspond to setting up of enhanced ring current? or is it a local current signature (if so no evidence in local particles).

## Polar/CEPPAD & Cluster/RAPID and PEACE PADs

**Polar/CEPPAD & Cluster/RAPID and PEACE PADs**

**Notes:**
As previous slide but for pitch angles. Loss of perpendicular particles 

## Scenario A: X-line formation tailward of Cluster

**Scenario A: X-line formation tailward of Cluster**

-  Tail sheet thinning (i).
-  Tail thinning takes Cluster from the plasma sheet into the lobe (ii).
-  X-line formation tailward of Cluster (iii).
-  Cluster is re-engulfed by the expanding plasma sheet (iv).
-  This is consistent with observations for event A.
-  This is not consistent with B, however, where Cluster exits the plasma sheet after substorm onset.

**Notes:**
Scenario – 1 from ML which is standard picture of thinning and expanding plasma sheet for NENL tailward of Cluster.

## Scenario B: X-line formation Earthward of Cluster

-  X-line formation Earthward of Cluster (vi).
-  Cluster remains in the proto-plasmoid until tailward X-line migration takes it into the lobe (vi).
-  Cluster remains in the lobe as X-line migrates tailward (vii) until being re-engulfed by the plasma sheet (viii).
-  This scenario is consistent with observations for event B (and A).

**Scenario B: X-line formation Earthward of Cluster**

**Notes:**
The alternative scenario that is used to explain event B with NENL forming earthward of Cluster and then migrating tailward.

## Summary

-  Results have been presented for a series of intense energetic particle signatures in the magnetotail.
-  The signatures are considered to be the result of repeated incursions into the tail plasma sheet in response to tail reconfiguration in a series of substorms.
-  Pitch angle distributions are consistent with Fermi acceleration for R > ~10 Re and Betatron for R < ~10 Re (Smets et al, 1999).
-  The particle and field observations are most consistent with a scenario in which the plasma sheet expands tailward over the spacecraft in the wake of a tailward-moving reconnection X-line.

**Notes:**
Conclusions just taken out of the paper