M. Yamauchi1, H. Nilsson1, R. Lundin1, I. Dandouras2, H. Reme2, H. Frey3, P.W. Daly4, E. Kronberg4, P.-A. Lindqvist5, M. Andr6, A. Balogh7

(1) Swedish Institute of Space Physics, Kiruna, Sweden (2) CESR, Universite de Toulouse, Toulouse, France (3) SSL, University of California, Berkeley, CA, USA (4) Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany (5) Alfven Lab., Royal Institute of Technology, Stockholm, Sweden (6) IRF, Uppsala, Sweden (7) Blackett Lab., ICL, London, UK

Inner magnetospheric condition for inbound-outbound asymmetry in the

CIS ion data

They are normally north-south symmetric (except seasonal effect) because these ions are bouncing between southern and northern hemispheres (cf. Cluster inbound & outbound).

(1) However, some Cluster traversals show inbound-outbound asymmetry in the ion data.

How much are they related to substorms?

(2) In addition we found new(probably?) type of low-energy trapped ions near equator. It is similar to radiation contamination, but are different (this is the reason they have been overlooked). It is similar to plasmasphere, but probably(?) different.

We examined all perigee pass during 2001-2006 (with caution on 2006 data).

Sub-to several-keV ion patterns in the inner magnetosphere (near perigee of Cluster)

Hanging stripes = “Sudare” type9 LT

“sudare”

15 hours

AL

AU

1000 nT

-2000 nT

-1000 nT

9 LT

asymmetric “sudare”

At post-midnight to morning: eastward drift ExB drift! strong E

(note “sudare” itself is mainly found in night)

VB energy (mass independent)

VExB = constant (energy mass)

dispersed sub-keV ion = “wedge”

dispersed sub-keV ion = “wedge”

AE=qiuetAE=just diminished

asymmetric “wedge”

At morning to noon: “fossil” of eastward drift may suddenly appear within 1 hour as fixed place.

wedge-like but at several-keV (plasma sheet?) = “PS-wedge” type

“PS-wedge”

15 hours

1000 nT

-2000 nT

-1000 nTAE=1 hour after substorm

asymmetric “PS-wedge”

At post-midnight to morning: eastward drift(This is confirmed from “lower-energy than gap”)

Asymmetry sometimes appears as internal structure (no model yet)

AE=qiuet

AE=qiuetAE=long substorm

no preference of AE = not related to substorm?

Internal structure

At morning to noon: same as “wedge”

AE=after onset

low-energy structures

look at many cases reveals that no preference of AE

asymmetric “low-energy”

signature

Reason of noon peak could be because the other signature does not hide...

(1) Asymmetric “Sudare” (vertical stripes of 1~10 keV ions) postmidnight@substorm onset

(2a) Asymmetric “Wedge” (dispersed stripe at sub-keV)(2b) Asymmetric “PS-wedge” (long stripes of few keV ions)(2c) Asymmetric internal structure of “Wedge”

(2a and 2c) prenoon@some hours after substorm activity (2b) early morning@substorm activity

(3) Asymmetric “Low-energy” (~0.1 keV ions) noon@no preference

Summary of asymmetric cases We examined ion (CIS) data for all Cluster perigee traversals during 2001-2006 when the orbit is relatively north-south symmetric (2006 data is affected by orbit). Except seasonal effect, we found following north-south asymmetry in the inner magnetosphere.

Equatorial trapped 100 eV H+

AE=quietAE=small

Equatorial trapped 100 eV H+

At all LT except night. obvious candidate is plasmaspheric H+, but exists without substorm and in the afternoon.

Summary of 100 eV trapped H+

* Similar to but different from the radiation belt contamination.

* About 100 eV, only H+ without O+

* All LT except night could be “energized” plasmaspheric ions. However,

* Even observed during long quiet period Substorm (electric field) is unlikely related for the transportation to the afternoon. Could directly be supplied from the ionosphere, which has been observed during quiet time.

other substorms

combinations

11 LT 06 LT 08 LT 07 LT

camera’s FOV is not optimum (aurora is active>)

16:28 UT

onset SIE SIEonset

18:28 UT

SIE

02:40 UT

Presented at Chapman Conference on Aurora (Feb 2011)