Inner magnetospheric condition for inbound-outbound asymmetry in the CIS ion data 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

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

Hanging stripes = “Sudare” type 9 LT Hanging stripes = “Sudare” type

“sudare” 9 LT 1000 nT AU -1000 nT AL -2000 nT 15 hours

asymmetric “sudare” At post-midnight to morning:  eastward drift  ExB drift!  strong E (note “sudare” itself is mainly found in night)

dispersed sub-keV ion = “wedge” VB  energy (mass independent) VExB = constant (energy  mass)

dispersed sub-keV ion = “wedge” AE=qiuet AE=just diminished dispersed sub-keV ion = “wedge”

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” 1000 nT -1000 nT AE=1 hour after substorm -2000 nT 15 hours

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

no preference of AE = not related to substorm? AE=qiuet AE=long substorm no preference of AE = not related to substorm?

Internal structure At morning to noon:  same as “wedge”

low-energy structures look at many cases reveals that no preference of AE AE=after onset

asymmetric “low-energy” signature Reason of noon peak could be because the other signature does not hide...

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. (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

Equatorial trapped 100 eV H+ AE=quiet AE=small Equatorial trapped 100 eV H+

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

Presented at Chapman Conference on Aurora (Feb 2011) 11 LT 06 LT 08 LT 07 LT onset SIE SIE SIE onset camera’s FOV is not optimum (aurora is active>) 18:28 UT 16:28 UT 02:40 UT Presented at Chapman Conference on Aurora (Feb 2011)