Fate of outflowing ions from the Earth's ionosphere: current knowledge and remaining questions Part 2 M. Yamauchi

Summarizing ion dynamics Leak (magnetopause shadowing)

Summarizing ion escape route

Main escape mechanisms for present Earth Where? Jeans escape exobase (M, ancient E?) Hydrodynamic blow off near exobase (ancient) Momentum exchange above exobase (M, ancient E/V?) Photochemical energization exosphere (M, ancient) Charge-exchange above mirror altitude (E) Atmospheric sputtering around and above exobase (M, V>E) Ion pickup outer exosphere (M>V, ancient E?) Ions accelerated by field reach SW ionosphere & magnetosphere (E>M>V?) Large-scale momentum transfer & instabilities magnetospheric boundary and tail (E>M, V) Magnetopause shadowing (ions) inner magnetosphere (E) Plasmaspheric wind and plumes plasmasphere (E) neutrals both mixed ions

Main escape mechanisms for present Earth skip? mechanism explanation determining factors Jeans escape Thermal tail exceeds the escape velocity T, n, and height of exobase Hydrodynamic blow off Massive escape when thermal energy exceeds escape energy Momentum exchange Light neutrals collide with heavy molecules Outflow H flux & ambient O density along this path Photochemical energization Recombination etc. supply the escape energy Charge-exchange Trapped ion with escape velocity strives an electron from neutral trapped O+ flux & ambient O density near mirror altitude Atmospheric sputtering Precipitating heavy ions (pickup or trapped ones) impact the atmosphere Precipitating ion flux into the exobase Ion pickup Cold ions that are newly exposed to solar wind are removed by the solar wind ExB n of cold ions outside the magnetopause Ions accelerated by field reach SW E// acceleration (DC field) and wave-particle interactions (AC field). DC and AC field and background ion (n, T, V) Large-scale momentum transfer & instabilities Solar wind PDynamic and EM forces push the planetary plasma anti-sunward. solar wind n, V, B, solar UV, & magnetopause size Magnetopause shadowing (ions) The drifting ions overshoot the magnetospheric boundary. inner magnetospheric E Plasmaspheric wind and plumes Detachment or expansion of cold plasma by instability or pressure T, n and E in the plasmasphere neutrals both mixed ions

Known escape rate with Cluster (a) polar outflow of hot O+ (x 1025 s-1) magnetosheath O+ (escape) ~ 0.7 plasma mantle O+ (mostly escape) ~ 2 (Nilsson et al. 2012, Slapak et al., 2017a) (b) magnetotail hot O+ (x 1025 s-1) tailward O+ (escape) ~ 0.5 earthward O+ ~ 0.6 ⇒ roughly half escapes later (Slapak et al., 2017b) (c) plasma sheet cold H+ (x 1025 s-1, with O/H ratio < 10-2 ?) 3 ~ 10 (for H+) ⇒ more than half escapes (Eriksson et al. 2006, Engwall et al., 2009) (d) plasmaspheric cold H+ and He+ (x 1025 s-1, with O/H ratio ~ 10-2) Plume : peak 100 (for H+) Wind : 50 (for H+) (Darrouzet et al. 2009, 2013)

Ion loss rate: Earth > Mars, Venus skip? because of size cf. Mars cf. Venus Earth Cluster@>4 Re@2001-2005 (Nilsson et al., 2011, 2012)

Nilsson et al. 2012 Slapak et al. 2017 Known escape rate: x 1025 s-1 skip? (a) polar outflow Satellite R (Re) Energy Range keV Outflow Rate (1025 s-1) References H+ O+ Cluster (CIS) > 8 0.028-40 escape ~ 2 Nilsson et al. 2012 Slapak et al. 2017 Cluster (EFW) > 10 supersonic tail ~ 10 Engwall et al. 2009 Polar (Apogee) 8.5 0.015–33 1 outflow ~ 1.5 Lennartsson et al. 2004 DE–1 4 0.010–17 outflow ~ 0.7 Yau et al. 1986 Collin et al. 1988 Polar (Perigee) 2-2.3 0.3 outflow ~ 0.3 Peterson et al. 2001 Akebono 2.3 < 0.07 2 outflow ~ 0.2 Cully et al. 2003a FAST 1.4 0.003–12 - Andersson et al. 2005 (b) magnetotail (x 1025 s-1) tailward O+ (escape) ~ 0.5 earthward O+ ~ 0.6 ⇒ roughly half with escape (Slapak et al., 2017b) (c) plasmasphere / Cluster (x 1025 s-1, only H+ and He+, with O/H ratio ~ 10-2) Plume (H+): peak 100 (Darrouzet et al. 2009) Wind (H+) : 50 (Darrouzet et al. 2013)

Outline (1) Types of outflow (cold filling, cold/superthermal outflow, hot outflow) and primary destinations (2) Ions that are not directly escaping: Inner Magnetosphere as a zoo of ions time-variable multiple sources time-variable E-field local energization expected/unexpected mass-dependency (3) Amount of ion escape and its consequence: Evolution of the Earth in geological scale (then cannot ignore neutral) If we have time….. (4) Active roles of terrestrial (planetary) ions in local energy conversion through mass-loading in bow shock structure and foreshock formation (5) Ions in the neutral atmosphere: Unique method to monitor ionizing radiation

Scaling to the past : high EUV + PSW Ancient solar forcing (young M-stars) (a) much higher EUV flux than present (b) faster solar wind than present (c) much faster rotation than present ⇒ stronger solar dynamo ⇒ stronger flare / CME / SEP (Solar Energetic Particle) (e.g., Wood, 2006) ⇒ We scale Kp=10 or use extreme events as proxy of the past (Tu et al. 2015, Lammer et al., 2018)

Geological-scale evolution skip? (f) Can we guess the past escape? cf. Sun-in-Time project (e.g., Wood 2006) → higher EUV, faster SW, stronger IMF, stronger CME, → scaling to Kp=10 (Slapak et al., 2017a) or use extreme events as proxy (Krauss et al., 2012; Schillings et al., Thursday 9:00 am), 2003-10-29 event ≈ 2.3 billion y.a. (g) Any effect on atmospheric composition, e.g., O/N ratio? cf. O+/H+ ratio increases with EUV/Kp (e.g., Maes et al., 2015), and N+/O+ ratio also increases with EUV/Kp (Yau et al., 1993). → Billions years ago, N+/O+ ratio might have been ≥ 1. → total loss of hot N+ and hot O+ could be 0.5·1018 kg over4 billions y.a. → Atmospheric O/N ratio was different by ~8% → Escape (only hot component) could have affected the biosphere ! (h) What is missing / Future measurements: include changes in the source cf. Exosphere-Ionosphere-Magnetosphere/Plasmasphere coupling → future missions

Consequence of high EUV + PSW in the past skip? 1026/s 1026/s 1025/s 1025/s 1024/s Loss rate: FO+ µ P2.5 Loss rate : FO+ µ exp(0.45*Kp) PSW Kp=1 Kp=7 1 nPa 10 nPa (Slapak et al., 2017b) Cluster@2001 – 2005 (Schillings et al., 2019) For only direct escape (O+ mixing into the solar wind), we expect 1027 s-1 for Kp=10 ⇒ 1027s-1 x 1 Gyr (3·1016 sec) = 3·1043 = 70% of present atmospheric O2 (15% of N2) ⇒ cannot ignore

Consequence of high EUV + PSW in the past skip? 1026/s (Slapak et al., 2017a) 1025/s 1024/s Loss rate : µ exp(0.45*Kp) Kp=1 Kp=7 For direct escape only (O+ mixing into the solar wind), we expect 1027 s-1 for Kp=10 Cluster@2001 – 2005 (Schillings et al., 2019) ⇒ 1027s-1 x 1 Gyr (3·1016 sec) = 3·1043 = 70% of present atmospheric O2 (15% of N2) ⇒ cannot ignore

Consequence of high EUV + PSW in the past (Slapak et al., 2017a) 1025/s 1024/s Loss rate : µ exp(0.45*Kp) Kp=1 Kp=7 For direct escape only (O+ mixing into the solar wind), we expect 1027 s-1 for Kp=10 Cluster@2001 – 2005 ⇒ 1027s-1 x 1 Gyr (3·1016 sec) = 3·1043 = 70% of present atmospheric O2 (15% of N2) ⇒ cannot ignore

Past atmospheric composition fluctuated Observed O/N ratio fluctuate in 0.1 byr : not easy to explain by bioactivity ⇒ escape matters? O2 concentration (Berner, 2006)

Before considering the other escapes Ancient solar forcing (young M-stars) (a) much higher EUV flux than present ⇒ thermosphere expands ⇒ neutral escape becomes large massive escape of O and N starts (x 6 present EUV) for N2 atmosphere (Tian et al., 2008) height 500 km 2000 km 10000 km veloicity 10.8 km/s 9.8 km/s 7.0 km/s O 9.7 eV 8.0 eV 4.1 eV N 8.5 eV 7.0 eV 3.6 eV before   after extra energy O2+ + e- ⇒ 2O 1–7 eV N2+ + e- 2N 3–6 eV boundary = "exobase"

In fact, exosphere drastically responds to EUV Newly-formed cold ions (pickup ions) at Mars ⇒ x 10 increase for <50% increase in EUV during 1 Mars year ⇒ expansion of exosphere is much more than any simple models appear for only < 7 hrs (Yamauchi et al., 2015)

Before considering the other escapes Ancient solar forcing (young M-stars) (a) much higher EUV flux than present ⇒ thermosphere expands ⇒ neutral escape (b) higher PSW than present (c) much faster rotation than present ⇒ stronger solar dynamo ⇒ frequent & intense flare/SEP (Solar Energetic Particle) ⇒ ion escape Ancient Earth (d) less geomagnetic field than present ⇒ magnetosphere shrinks Mars like interaction? (Yamauchi and Wahlund, 2007)

Can we "guess" O/H ratio of escape? skip? Was ancient Earth's atmosphere more oxide or reduced than now? Increase in EUV/FUV SWDP IMF (IMF) SEP Jeans & Photo-chemical (H, He) ++ same + Hydrodynamic (all) ++ (regime change) Ion pick-up (H, He) (#1) Wave and E// (all) (cf. Earth) Momentum transfer (all) O/H ratio of escape + (#2) #1) depending on relative extent of ionosphere and exosphere #2) because non-thermal > thermal for Earth-sized planet

Fate of outflowing ions: Summary skip? mechanism explanation determining factors Jeans escape Thermal tail exceeds the escape velocity T, n, and height of exobase Hydrodynamic blow off Massive escape when thermal energy exceeds escape energy Momentum exchange Light neutrals collide with heavy molecules Outflow H flux & ambient O density along this path Photochemical energization Recombination etc. supply the escape energy Charge-exchange Trapped ion with escape velocity strives an electron from neutral trapped O+ flux & ambient O density near mirror altitude Atmospheric sputtering Precipitating heavy ions (pickup or trapped ones) impact the atmosphere Precipitating ion flux into the exobase Ion pickup Cold ions that are newly exposed to solar wind are removed by the solar wind ExB n of cold ions outside the magnetopause Ions accelerated by field reach SW E// acceleration (DC field) and wave-particle interactions (AC field). DC and AC field and background ion (n, T, V) Large-scale momentum transfer & instabilities Solar wind PDynamic and EM forces push the planetary plasma anti-sunward. solar wind n, V, B, solar UV, & magnetopause size Magnetopause shadowing (ions) The drifting ions overshoot the magnetospheric boundary. inner magnetospheric E Plasmaspheric wind and plumes Detachment or expansion of cold plasma by instability or pressure T, n and E in the plasmasphere neutrals both mixed ions

Additional escapes for ancient Earth skip? mechanism explanation Where? Jeans escape Thermal tail exceeds the escape velocity exobase (M, ancient E?) Hydrodynamic blow off Massive escape when thermal energy exceeds escape energy near exobase (ancient) Momentum exchange Light neutrals collide with heavy molecules above exobase (M, ancient E/V?) Photochemical energization Recombination etc. supply the escape energy exosphere (M, ancient) Charge-exchange Trapped ion with escape velocity strives an electron from neutral above mirror altitude (E) Atmospheric sputtering Precipitating heavy ions (pickup or trapped ones) impact the atmosphere around and above exobase (M, V>E) Ion pickup Cold ions that are newly exposed to solar wind are removed by the solar wind ExB outer exosphere (M>V, ancient E?) Ions accelerated by field reach SW E// acceleration (DC field) and wave-particle interactions (AC field). ionosphere & magnetosphere (E>M>V?) Large-scale momentum transfer & instabilities Solar wind PDynamic and EM forces push the planetary plasma anti-sunward. magnetospheric boundary and tail (E>M, V) Magnetopause shadowing (ions) The drifting ions overshoot the magnetospheric boundary. inner magnetosphere (E) Plasmaspheric wind and plumes Detachment or expansion of cold plasma by instability or pressure plasmasphere (E) neutrals both mixed ions

Main escape mechanism for ancient Earth present Earth ancient Earth? Jeans escape - yes? (need to understand present exosphere) Hydrodynamic blow off Momentum exchange Photochemical energization yes Charge-exchange ? (need to understand ring current) Atmospheric sputtering yes? (need to understand past cusp) Ion pickup Ions accelerated by field reach SW YES ! Large-scale momentum transfer & instabilities yes? (need to understand past magnetosphere) Magnetopause shadowing (ions) yes? (need to understand past ring current) Plasmaspheric wind and plumes yes? (need to understand past plasmasphere) neutrals both mixed ions

Outline (1) Types of outflow (cold filling, cold/superthermal outflow, hot outflow) and primary destinations (2) Ions that are not directly escaping: Inner Magnetosphere as a zoo of ions time-variable multiple sources time-variable E-field local energization expected/unexpected mass-dependency (3) Amount of ion escape and its consequence: Evolution of the Earth in geological scale (then cannot ignore neutral) If we have time….. (4) Active roles of terrestrial (planetary) ions in local energy conversion through mass-loading in bow shock structure and foreshock formation (5) Ions in the neutral atmosphere: Unique method to monitor ionizing radiation

O+ inside solar wind = Mass Loading Mass loading = inelastic mixing conserving momentum ⇒ kinetic energy is not conserved (∆K/K = ∆u/u= deceleration rate) example 1: comets and Mars (loading of pickup ions) example 2: cusp & plasma mantle (mixing of escaping O+)

In fact Cluster obs. indicates Mass Loading VO+ increases while VH+ decreases ⇒ Mixing is indeed inelastic toward the common velocity ⇒ ∆K/K = ∆u/u (Yamauchi and Slapak, 2018)

O+ inside solar wind = mass loading skip? Momentum conservation ⇒ kinetic energy extraction e.g., nO+/nSW~0.01 ⇒ rO+/rSW~0.16 ⇒ 7% of kinetic energy (109-10 W) to J// etc. large Kp ⇒ high rO+/rSW ⇒ high VO/VH? Nonstorm Cluster (CIS-4) 2001-2005 Lobe Cluster/CIS (Yamauchi and Slapak, 2018) cusp |V| Storm Lobe cusp Kp extra acceleration! How much does mass-loading increase the escape rate??? (Liao et al., 2015) eV

In fact Cluster obs. indicates Mass Loading Where does ∆K go? Ionosphere! because connected by geomagnetic field (same mechanism as "open" magnetosphere) ⇒ Two type of "open": looking from the Earth (Dungy type), and looking from the solar wind (Vasyliunas type)

Energy conversion by Mass Loading If final VO+ ≈ VH+, ∆K is independent of ionospheric conductivity: ∆K ≈ (-1/4)·u2SW·Fload (where F is O+ mixing rate to the solar wind) (1) ∆K ≈ 109-10 W for Fload ≈ mO*1025-26 s-1 ⇒ Can explain cusp current system (amount + independency) (2) We expect Fload µ ∆K (through ionospheric heating) ⇒ Large uSW increases O+ escape?  YES (3) O+ outflow influence the SW injection? ⇒ Various types of injection? (not all are understood) (Yamauchi and Slapak, 2018) (Schillings et al., 2019)

Variety of Solar Wind injections All are equatorward of the cusp, and some are unexplained (Yamauchi and Lundin, 2001) FTE cusp=heating (Yamauchi et al., 2003)

skip?

Other active effect of planetary ions? Martian bow shock E-field : high enough to reflect the solar wind only when cold ions does not exist Rough survey over 2005-2010: out of phase between foreshock and pick-up ions (Yamauchi et al., 2015a) foreshocks foreshocks foreshocks

Martian bow shock "double" foot skip? BS SW Martian bow shock "double" foot n: BS normal direction.

Martian bow shock "double" foot (Yamauchi et al., 2011) ordinary foot (700 km) Mars Express, 2005-7-12 inner foot (300 km) = heated beam (cold ion origin?)

First guess = size, but (1) size: finite gyroradius effect SW parameter RS (BS radius) MA (n1/2 V/B) c/pi ( n-1/2) & c/piRS rg ( V/B) & rg/RS Venus 1 1 & 1 Earth ~ 5 ~ 1.2 ~ 1.7 & ~ 0.3 ~ 2 & ~ 0.4 Mars ~ 0.5 ~ 1.4 ~ 3 & ~ 5 ~ 4 & ~ 8 For Mars: RS ~ 5000 km for Martian Subsolar 2 keV H+ under 6 nT  rg = 1000 km 5/cm3 H+  c/pi = 100 km (2) cold ions: only Mars has cold ion at bow shock

Two types of quasi-perpendicular bow shock Foreshock + foot morphology ⇒ B-field direction for reflected solar wind is important (1) QL (2) QP type 1 (3) QP type 2 (field-aligned beam) field-aligned beam multiple bounce (Yamauchi et al., 2012)

Reflections at bow shock skip? QT QT QL FS oblique acceleration ^ acceleration ^ & // acceleration // acceleration escape escape (Yamauchi et al., 2012)

High E-field of Martian bow shock Even O+ are accelerated to 1 keV inside bow shock if cold ions is little (Yamauchi et al., 2015b) f=5 f=4 f=3 f=2 Proton f=5 f=4 f=3 f=2 Oxygen

Outline (1) Types of outflow (cold filling, cold/superthermal outflow, hot outflow) and primary destinations (2) Ions that are not directly escaping: Inner Magnetosphere as a zoo of ions time-variable multiple sources time-variable E-field local energization expected/unexpected mass-dependency (3) Amount of ion escape and its consequence: Evolution of the Earth in geological scale (then cannot ignore neutral) If we have time….. (4) Active roles of terrestrial (planetary) ions in local energy conversion through mass-loading in bow shock structure and foreshock formation (5) Ions in the neutral atmosphere: Unique method to monitor ionizing radiation

Finally, ions in the neutral atmosphere E (V/m) s (S/m) 30 km Main ionization source is cosmic ray ~ 3 pA/m2 ground ~ 100 V/m < 10-13 S/m j (pA/m2)

radioactive material increases ion density

Radioactive material increases ion density After Chernobyl accident, 1986 (Tuomi, 1988) vertical E (V/m) Rain 2 weeks After Fukushima accident, 2011: vertical E increase again ! vertical E (V/m) (Takeda et al., 2011)

Radioactive material increases ion density migrate into the soil ⇒ gradual recovery from E=0 attached to surface ⇒ re-suspend by strong wind floating near surface ⇒ easily re-suspend From vertical E-field, we could derive the motion of radioactive materials ⇒ Six period is deduced! (Yamauchi et al., 2012)

Summary (1) Out of three type of outflow (cold filling, cold supersonic outflow, hot outflow), hot O+ alone cause >10 25-26 s-1 mainly though direct entry into the solar wind in the polar region. (2) Inner Magnetosphere is a zoo of "un-understood" ions. (3) Ion escape influences evolution of the Earth in geological scale ⇒ We still need missions to study "escape" (Friday morning) (4) Terrestrial/planetary ions plays active roles in the solar wind interaction with the magnetosphere (5) Knowledge of ion dynamics even allows monitoring radioactive materials

Thank you