cusp

O+

H+e-"SPI"

event #1event #2

MLT 11 12 13 14

energy ratio = 15~20O+

H+

68°CGLat 66°CGLat 63°CGLat

#1) Mono-energetic ion injection with O+ faster than H+ (13 LT)VF source > 10 Re (TOF distance ~ 1 Re). From the southern cusp (ionosphere) Mass-filtering mechanism ???

#2) O+ injection (lower energy than H+) adjacent to the cuspOnly this event among > 100 cusp Freja-FAST discrepancyGeneration mechanism ???

1994-2-21 event13 MLT

IMF By ≈ -50 nT Kp=7+Major storm-time

(A) Unusual O+ injection

"wedge" event #3

(1) (2) (3)

9 MLT 10 MLT

O+H+e-e-

60°CGLat 66°CGLat

P/A=0~90°

P/A=90~180°

P/A=40~140°O+O+O+

radiation belt?

63°CGLat

1992-12-28 event9 MLT

Kp=6-Major storm-time

#3) Multiple dispersive O+ injections from a nearby source* In oblique direction * Non-gyrotropic distribution* Sudden localized anisotropic energization at < 1000 km.Generation mechanism is a mystery ???

correlated & anti-correlated

(1) O+ source ≠ H+ source(B) H+/O+ in the major return route

(2) O+ motion ≠ H+ motion

H+

O+

Correlation part means that H+ and O+ has the same bounce-average drift motion. Then, how can we understand the anti-correlation part just 15 minutes later?

O+

O+

H+

H+

O+ appears earlier than H+. Drift of O+ is not bounce-averaged motion seen from pitch angles,

(C) Roles of escaped O+

Earth ?Mars ?Venus ?Io & otherSatellites?

(1)Mass loading at the exterior cusp :

Extra deceleration of SW

(2) Enhanced Hall effect:

Because of quicker O+/e- separation than H+/e- separation Electrons start to divert from the plasma flow at a larger distance for storm time tha non-storm time (critical thickness of the current sheet changes) Storm-time reconnection & current disruption is faster than non-storm-time reconnection & current disruption.

end

Returning O+ from the Magnetosphere to the Ionosphere

M. Yamauchi (Swedish Institute of Space Physics, Kiruna)and

Viking-V3 / Freja-F3 / Cluster-CIS teams(1) We surveyed heavy ion injections at 1700 km (Freja) altitude

* Mostly found in nightside subauroral region. * We show three of them the rare (few %) dayside events

(2) We found O+/H+ difference in the sub-keV ring current plasma* Evidences of source difference between O+ and H+* Drift average for H+ whereas non-drift average for O+

(3) Roles of escaped O+ : cusp mass-loading and tail reconnection

Cross-disciplinary importance of O+ circulation* Evolution of Earth, planets, satellites* Modeling of ancient Earth* Atmospheric environment* Chemistry of reservoir (CO2, SiO2, SO) * Basic plasma physics* Solar-terrestrial physics (energy and mass transfer)* General plasma/neutral circulation in the exosphere

Fact: # O+ escapes a lot (1~10 kg/s from Earth/Mars)

# O+ behaves differently from H+ (for return)

# But O+ return is not well studied

ion escape H+ O+

< 10 eV (2~3 Re) 2~5 1~3> 10 eV (3~4 Re) 2~8 1.5~20

ion precipitation ion electron

> 10 eV (DMSP) 0.2~0.9 9~60in 1025 /s

mass budget H+ O+ meteors

out 0.05~0.2 0.5~5 -

in < 0.02 ??? 0.5in kg/s After Moore et al., 1999

Examples of O+ escape

Phobos-2: O+ escape from Mars [Lundin et al., 1990]. High escape rate : 0.1 ~ 1 kg/s (obs. by Mars Express and Phobos 2)

Cluster: non-thermal O+ escape from the ionosphere [Nilsson et al., 2004].

H+O+

O+H+e-

O+,O2+

O+H+

EM

-matr ix

ET s p ec tr o gr am

Freja: Escape of ions (mostly O+) due to wave-heatings (three types) [Norqvist et al., 1998].

(1) O+ injection eventsO+

H+

e-

O+

H+

e-Commonly-found ion injections near or equatorward of the nightside auroral zone.

O+ = not well-studied

H+ = well-studied

Freja observation of general ion injections in the nightside sectors

(1a) Most injection events occur in the nightside

Freja statistics shows clear nightside preference

Not artifact of 63°inclination

Some in daysideThe total number of traversals with clear injection events in each bin is scaled by the size of the square. The numbers with # are the orbit number.in 1° x 1h bin.

Freja data 1992.10 ~ 1994.10

cusp

O+

H+

e-" SPI "

event #1

event #2

11 MLT 12 MLT 13 MLT 14 MLT

energy ratio = 15~20O+

H+68°CGLat 66°CGLat 63°CGLat

"wedge"

event #3

(1) (2) (3)

9 MLT 10 MLT

O+

H+e-e-

60°CGLat 66°CGLatP/A=0~90°

P/A=90~180°

P/A=40~140°O+

O+

O+

radiation belt?

63°CGLat

(1b) Unusual events in the dayside

#1) Mono-energetic ion injection with O+ faster than H+ (13 LT)VF source > 10 Re (TOF distance ~ 1 Re). From the southern cusp (ionosphere) Mass-filtering mechanism is unknown

IMF By ≈ -50 nT , Kp=7+ Kp=6-

#2) O+ injection (lower energy than H+) adjacent to the cusp* Only this event* Freja-FAST discrepancyGeneration mechanism is unknown

1994-2-21 1992-12-28

#3) Multiple dispersive O+ injections from a nearby source* In oblique direction * Non-gyrotropic distribution* Sudden localized anisotropic energization at < 1000 km.Generation mechanism is a mystery

(2b) O+ motion ≠ H+ motion

H+

O+

H+

O+

H+

O+

H+ obeys bounce-average, whereas O+ shows non-averaged effect

Summary1. There are more mechanism of ion escape/return from/to the ionosphere than a simple thought. Even now, we have many un-understood ion escape/return mechanisms.

Mars: unexpected high loss rate ~ 1 kg/s

vH+

nH+

nO+

nO2+

Even higher flux is observed for the Earth (100~500 ton/day).Lundin et al., 1990

Mars: quick energization of O+ is confirmed

Lundin et al., 2004

Ion heating/escape (Freja example)

[eV]

103

101

103

101

10

0.1

[eV]

O+

H+

Density

e-

Freja orbit 1798 (1993-2-19)

— Transverse Acc. outflow —— Bulk plasma outflow —

O+ injection : it returns (we don't know the amount)

Yamauchi et al., 2005

Budget above the Earth's ionosphereion escape H+ O+

< 10 eV (2~3 Re) 2~5 1~3> 10 eV (3~4 Re) 2~8 1.5~20

ion precipitation ion electron

> 10 eV (DMSP) 0.2~0.9 9~60in 1025 /s

mass budget H+ O+ meteors

out 0.05~0.2 0.5~5 -

in < 0.02 ??? 0.5in kg/s After Moore et al., 1999

Budget above the Earth's ionosphereion escape H+ O+

< 10 eV (2~3 Re) 2~5 1~3> 10 eV (3~4 Re) 2~8 1.5~20

ion precipitation ion electron> 10 eV (DMSP) 0.2~0.9 9~60in 1025 /s

mass budget H+ O+ meteorsout 0.05~0.2 0.5~5 -in < 0.02 ??? 0.5in kg/s

After Moore et al., 1999

We examined all heavy ion data of Freja satellite (1992.10-1994.10)* Most injection events occur in the nightside* Some unusual events in the dayside

(1) Mono-energetic injection with O+ faster than H+ (13 LT)VF source > 10 Re (TOF distance ~ 1 Re). From the southern dayside ionosphere (cusp)Mass-filtering mechanism is unknown

(2) O+ injection (lower energy than H+) adjacent to the cuspFreja-FAST discrepancyGeneration mechanism is unknown

(3) Multiple dispersive O+ injections from a nearby source In oblique direction with non-gyrotropic distribution

Sudden localized anisotropic energization at < 1000 km.Generation mechanism is a mystery

(1) O+ injection events

(2) H+/O+ in major return route

correlated & anti-correlated

(2a) O+ source ≠ H+ source