REPRESENTATION OF PLASMA TEMPERATURES IN IRI Vladimir Truhlik

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 REPRESENTATION OF PLASMA TEMPERATURES IN IRI Vladimir Truhlik Department of the Upper Atmosphere

REPRESENTATION OF PLASMA TEMPERATURES IN IRI Vladimir Truhlik Department of the Upper Atmosphere Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic Praha, Czech Republic Email : vtr@ufa. cas. cz

Outline • Introduction • Tools – Data – Theoretical model • Plasma temperatures –

Outline • Introduction • Tools – Data – Theoretical model • Plasma temperatures – Theory and basic processes – Representation in IRI • Electron temperature • Ion temperature • Swarm, LP data, access • Conclusions COSPAR CBW 2

Introduction • Knowledge of characteristics of ionized part in the Earth‘s outer atmosphere is

Introduction • Knowledge of characteristics of ionized part in the Earth‘s outer atmosphere is important for studying of many phenomena especially propagation of electromagnetic signals (artificial – GPS; natural - VLF - whistlers, emissions etc. ) • Most important parameters which we study: – Electron density (Ne) (propagation of radio waves) – Ion composition (e. g. , waves - whistler mode – LHR Lower Hybrid Resonance – important mean ion mass) – Plasma temperatures (thermal balance, important for transfer of energy, scale height etc. ) • Electron temperature (Te) • Ion temperature (Ti) – Drifts etc. COSPAR CBW 3

IRI model • Ne electron density – parameter of prime interest • Electron temperature,

IRI model • Ne electron density – parameter of prime interest • Electron temperature, ion composition (O+, He+, molecular ions), drifts, ionospheric electron content (TEC), F 1 and spread-F probability COSPAR CBW 4

Tools – data Data base – satellite data All available Te satellite data (source

Tools – data Data base – satellite data All available Te satellite data (source mainly NSSDC, ISAS, and PIs of individual experiments) Year-altitude coverage of the data sets include in our data base. The curve at the top shows the solar 10. 7 cm radio flux (F 10. 7 index – 3 months average). COSPAR CBW 5

Tools – model Field Line Interhemispheric Plasma (FLIP) flow model (e. g. Richards, 2001;

Tools – model Field Line Interhemispheric Plasma (FLIP) flow model (e. g. Richards, 2001; Richards, 2002) Includes: -Continuity and momentum equations along the field line for O+, He+, and N+. -Energy balance equations for electrons and ions. Geometry of tilted offset dipole -Two stream photoelectron model -Photochemical equilibrium below 500 km for ions NO+, O 2+, N 2+, O+(2 P), and O+(2 D) - Continuity and momentum equations for minor neutral species NO, O(1 D), N(2 D), and N(4 S) from 100 to 500 km in each hemisphere -Ex. B drift Inputs: -EUV from EUVAC model -Horizontal winds from HWM model or from equivalent winds obtained from measured hm. F 2 -Neutral densities and temperature from the MSIS model -Equatorial drift from e. g. , Fejer-Scherliess model COSPAR CBW 6

Ionospheric plasma Ionosphere-plasmaphere system, part of the inner magnetosphere (interacts with regions below and

Ionospheric plasma Ionosphere-plasmaphere system, part of the inner magnetosphere (interacts with regions below and above) • Ionization of neutral atmosphere by solar EUV or energetic particles precipitation • Energy of particles<1 e. V, high density (up to 1013 m-3) • Quasi-neutrality • Strong solar control, transport along magnetic field lines (upper ionosphere F 2 region, topside ionosphere, plasmasphere, high latitude region) • Ex. B drifts (equatorial region, high latitudes) COSPAR CBW 7

Plasma temperatures • Thermal motion of particles (electrons and ions) E=3/2 k. T •

Plasma temperatures • Thermal motion of particles (electrons and ions) E=3/2 k. T • Electron temperature (Te) • Ion temperature(s) • Temperature of neutral particles – important (Tn) up to >500 km COSPAR CBW 8

Plasma temperatures • Equation of energy balance (for particle i – ions or electrons)

Plasma temperatures • Equation of energy balance (for particle i – ions or electrons) n-density T-temperature k-Boltzmann constant κ- (kappa) thermal conductivity Q-source and loss of energy A – cross section of the flux tube COSPAR CBW 9

Electron temperature Equation of thermal balance (day, night – steady state - neglect changes

Electron temperature Equation of thermal balance (day, night – steady state - neglect changes with time) Qe – heating (from photoelectrons) local <350 km non-local plasmaspheric Le – cooling – very complex – energy loss: <350 km neutral particles O, N 2(r, v), O 2 (r, v) topside with ions O+, He+ (Coulomb) Ke – thermal conductivity I – inclination of the geomagnetic field FLIP electron cooling rates in the equtorial region up to 350 km as a function of altitude for various cooling terms (Coulomb —, r. N 2 —, r. O 2 —, v. N 2 —, v. O 2 —, fs. O ……, O 1 D …. . ). Coulomb cooling in the topside is dominant COSPAR CBW 10

Electron temperature – altitude profiles in topside and plasmasphere Thermal conductivity Te profile –

Electron temperature – altitude profiles in topside and plasmasphere Thermal conductivity Te profile – constant heat flux Te 0, G 0 – electron temperature and gradient (e. g. at 500 km) LSA COSPAR CBW HSA 11

Ion temperature Equation (neglect time changes, neglect heat flux) Qi – heating from electrons

Ion temperature Equation (neglect time changes, neglect heat flux) Qi – heating from electrons (Coulomb heating) Li – cooling: neutral particles O, N 2, O 2 and other ions (O+, He+ ) Resonant charge exchange Polarization reactions Rees and Roble, Rev. Geoph. and Sp. Ph. , 1975 COSPAR CBW 12

IRI Te model Bil-1985 - based on Brace and Theis Te maps (JASTP 1981)

IRI Te model Bil-1985 - based on Brace and Theis Te maps (JASTP 1981) – coordinates diplat and solar local time TTSA option (JASR 2001) replaced by new TBT-2012 (EPS, 2012) IRI 2012/IRI 2016 – JF(2)-. true. /. false. - Te, Ti computed/not computed – JF(23)-. true. /. false. -Bil-1985/TBT-2012 Ne/Te correlation (Brace and Theis, 1978) - JF(10) -. true. /. false. -Te – Standard /Te - Using Te/Ne correlation COSPAR CBW 13

Ne/Te correlation Brace and Theis, 1978 IRI 300 and 400 km COSPAR CBW 14

Ne/Te correlation Brace and Theis, 1978 IRI 300 and 400 km COSPAR CBW 14

Ne/Te correlation validity? Hinotori, daytime, equatorial latitudes Kakinami et al. , JGR 2011 “U”

Ne/Te correlation validity? Hinotori, daytime, equatorial latitudes Kakinami et al. , JGR 2011 “U” shape COSPAR CBW 15

TBT-2012 Te model Employs the all available satellite Te data Include solar activity variation

TBT-2012 Te model Employs the all available satellite Te data Include solar activity variation for day and night - an example for 550 km and equinox: Te PF 10. 7=90 16 Te PF 10. 7=200 Te PF 10. 7=150 Corrected Te model Data empirical profile Employs minimum of independent coordinates – to solve problem of limited data coverage Longitudinal structure neglected when it is used latitude coordinate based on the configuration of the real magnetic field – coordinates invdip and magnetic local time COSPAR CBW

Magnetic latitude coordinates diplat: where I is the dip angle or magnetic inclination -longitudinal

Magnetic latitude coordinates diplat: where I is the dip angle or magnetic inclination -longitudinal variation of Te reduced in equatorial latitudes Invariant latitude – invl (e. g. Roederer 1970): where the invariant radius R and the Mc. Ilwain L parameter obey -longitudinal variation of Te reduced at mid-latitudes (Smilauer and Afonin, ASR 1985) – plasma distributed along magnetic field lines invdip – combination of diplat and invl (Truhlik et al. 2001): COSPAR CBW 17

invdip (or invdiplat) magnetic local time (MLT) modified latitude – invdip (ASR Vol. 27,

invdip (or invdiplat) magnetic local time (MLT) modified latitude – invdip (ASR Vol. 27, No. 1, 101, 2001) longitudinal variation reduced to a second order effect ____ invdip _ _ _ dip latitude ____ invdip _ _ _ invariant latitude Configuration of the real geomagnetic field (IGRF 1990 at 600 km) in different latitude coordinates in steps of 10° COSPAR CBW 18

Data base – satellite data All available Te satellite data (source mainly NSSDC, ISAS,

Data base – satellite data All available Te satellite data (source mainly NSSDC, ISAS, and PIs of individual experiments) Year-altitude coverage of the data sets include in our data base. The curve at the top shows the solar 10. 7 cm radio flux (F 10. 7 index – 3 months average). COSPAR CBW 19

Te model - Data distribution KOMPSAT DMSP ISIS 2 AE ISIS 2 IK 24

Te model - Data distribution KOMPSAT DMSP ISIS 2 AE ISIS 2 IK 24 ISIS 1 Hinotori 9 million points – non-uniform distribution highest population corresponds to circularly orbiting satellites COSPAR CBW 20

350 km equinox Main (core) Te model solstice Data grouped - altitudes: 350, 550,

350 km equinox Main (core) Te model solstice Data grouped - altitudes: 350, 550, 850, 1400 and 2000 km seasons: equinox, solstice A system of associated Legendre polynomials up to the 8 th order was employed. 2000 km 1400 km 850 km 550 km Plm = associated Legendre function θ = invdip colatitude (0. . π) ϕ = magnetic local time (0. . 2π). -Te increases with altitude. - At low latitudes (± 30 invl) during the nighttime the Te altitude gradient is very small. - Morning enhancement (morning overshoot) at equatorial latitudes and at low altitudes (350, 550 to 850 km) - For solstices its maximum is shifted to the winter hemisphere - Dependence on invariant latitude is more prominent at lower altitudes (350 to 850 km). - Generally the lowest electron temperature is observed close to the equator and increases with increasing invariant latitude. 21

Model of the solar activity variation Solar activity variation of Te Qe and Le

Model of the solar activity variation Solar activity variation of Te Qe and Le depend on solar activity – increase with increasing solar activity => Te can increase, decrease or stay constant with increasing solar activity depending on altitude, latitude, local time and season COSPAR CBW 22

Model of the solar activity variation Driven by PF 10. 7 index PF 10.

Model of the solar activity variation Driven by PF 10. 7 index PF 10. 7=(F 107 A+F 107 D)/2 Normalized latitude profiles of Te for 3 levels of solar activity for day (13 h MLT) and night (1 h MLT): a) low PF 10. 7 < 110 b) medium 110 <= PF 10. 7 < 180 c) high F 10. 7=>180) – Quadratic fit inside 110 <= PF 10. 7 < 180; Outside linear extrapolation – Local time dependence approximated by a harmonic function – Obtain a correction function Te. PF 107(mlt, invdip, PF 107) For fixed altitude and local time Te(mlt, invdip, PF 107)=Te(mlt, invdip)+Te. PF 107(mlt, invdip, PF 107) COSPAR CBW 23

Solar activity correction function – example for 550 km equinox ∆Te/K PF 10. 7=(F

Solar activity correction function – example for 550 km equinox ∆Te/K PF 10. 7=(F 10. 7 D+F 10. 781)/2 Solar activity correction function—an example for 550 km equinox. * represent the normalized values from the normalized latitudinal profiles for low, medium and high solar activity. The dashed line represents a mathematical interpolation/extrapolation in solar activity using the three values. COSPAR CBW 24

Model of the solar activity variation of Te • • To include solar activity

Model of the solar activity variation of Te • • To include solar activity variation instead of Ti data use FLIP simulated values and the similar way as for TBT-2012 to use following approach: Driven by PF 10. 7 index PF 10. 7=(F 107 A+F 107 D)/2 Normalized latitude profiles of Ti for 3 levels of solar activity for day (13 h MLT) and night (1 h MLT) and also dawn (6 h MLT) and dusk (18 h MLT): a) low PF 10. 7 < 110 b) medium 110 <= PF 10. 7 < 180 c) high F 10. 7=>180) -Quadratic fit inside 110 <= PF 10. 7 < 180; Outside linear extrapolation -Local time dependence approximated by a smooth function -Obtain a correction function Te. PF 107(mlt, invdip, PF 107) For fixed altitude and local time Ti(mlt, invdip, PF 107)=Ti(mlt, invdip)+Ti. PF 107(mlt, invdip, PF 107)

Latitude profiles of Te high medium low solar activity 26

Latitude profiles of Te high medium low solar activity 26

Solar activity correction function – example for 550 km equinox ∆T/K PF 10. 7

Solar activity correction function – example for 550 km equinox ∆T/K PF 10. 7

IRI Ti representation IRI-2012 or IRI-2016 Altitude profiles (e. g. Bilitza, 1990): - at

IRI Ti representation IRI-2012 or IRI-2016 Altitude profiles (e. g. Bilitza, 1990): - at the altitude of 200 km Ti = Tn - Tn from MSIS(86) – includes solar activity variation 430 km Ti from the AEROS A model (latitudinal profiles for day and night, Bilitza 1981) Ti <= Te in topside Tn <=Te COSPAR CBW Tn Ti Te 28

Ion temperature - proposed model Data altitudes: 350 km, 550 km, 850 km, 1000

Ion temperature - proposed model Data altitudes: 350 km, 550 km, 850 km, 1000 km Latitude (invdip) and MLT 2 seasons, equinox no hemispheric differences Modeling grid 9 x 18=162 bins Spherical harmonics (orthogonal system) up to 8 th order Plm = associated Legendre function θ = invdip colatitude (0. . π) ϕ = magnetic local time (0. . 2π).

1000 km 850 km 550 km 350 km Contour plots of Ti – new

1000 km 850 km 550 km 350 km Contour plots of Ti – new Ti equinox solstice model -Ti increases with altitude. - At low latitudes (± 30 deg invl) during the nighttime the Ti altitude gradient is very small. - Morning enhancement (morning overshoot) at equatorial latitudes (550, 850 km) - For solstices its maximum is shifted to the winter hemisphere -Generally the lowest ion temperature is observed close to the equator and increases with increasing invariant latitude.

Relation of Te, Ti and Tn IRI Tn Tn Ti Ti Te COSPAR CBW

Relation of Te, Ti and Tn IRI Tn Tn Ti Ti Te COSPAR CBW 31

New data access - Swarm mission • • Project of ESA Primary purpose –

New data access - Swarm mission • • Project of ESA Primary purpose – monitoring of the geomagnetic field Launch date - 22 November 2013 (almost four years of data) Constellation of three identical satellites – Satellite A (Alpha) + C (Charlie) • • Altitude: ~480 km, inclination: 87. 4° side-by-side flying (Δlon: 1. 4°, ΔLT: 6 min) 160 km distance at equator Orbital delay: 6 s – Satellite B (Bravo) • Altitude: ~520 km, inclination: 88° • All satellites 270 days to cover all LT COSPAR CBW 32

Swarm mission - orbit Satellite local time Orbit altitudes Separation of the satellites -

Swarm mission - orbit Satellite local time Orbit altitudes Separation of the satellites - evolution COSPAR CBW 33

Swarm mission – future plans D. Sieg – Swarm DQW Oct. 2017 Preference -

Swarm mission – future plans D. Sieg – Swarm DQW Oct. 2017 Preference - keep Swarm alive at least one solar cycle COSPAR CBW 34

Swarm mission - experiments • Payload – Vector Field Magnetometer (VFM) – Absolute Scalar

Swarm mission - experiments • Payload – Vector Field Magnetometer (VFM) – Absolute Scalar Magnetometer (ASM) – Electric Field Instrument (EFI) – Accelerometer (ACC) – Laser Range Reflector (LRR) • Electric Field Instrument (EFI) – Measurement of density, temperature, drift velocity and electric field – Thermal ion imager (TII) – Langmuir probes (LP) COSPAR CBW 35

Langmuir probes - Swarm EFI • • • Developped by IRF Uppsala 2 probes:

Langmuir probes - Swarm EFI • • • Developped by IRF Uppsala 2 probes: Probe 1 in high gain, probe 2 in low Probe 1 – nitrated titanium (Ti. N) Probe 2 gold-plated titanium (Au) Data from probes telemetred to ground • • Principle: 128 Hz applied to the I-V characteristics Measure the resulting current “ripple” technique, harmonic (sub)mode – used ~99% 1% classical sweep COSPAR CBW 36

Langmuir probes – access to data • Various products released – 0. 5 s

Langmuir probes – access to data • Various products released – 0. 5 s Ne, Te - Provisional data set “PREL” (ASCII) (until July 2015) (harmonic mode, merged hi and low gain probes) – 0. 5 s Ne, Te – Level 1 b, Operational data set “OPER” (cdf) – (harmonic mode, high gain) from July 2015 – 16 Hz Ne - Faceplate plasma density (limited interval) only for validation – 0. 5 s Extended data set (both hi and low gain separately) only for validation – 128 s Ne, Te sweep mode - only for validation • ftp: //swarm-diss. eo. esa. int/ • Many products still in validation/correction/calibration process but it is already provided for scientific community - after registration COSPAR CBW 37

Conclusions • Global models of electron and ion temperatures are included in IRI •

Conclusions • Global models of electron and ion temperatures are included in IRI • These models include most important dependencies (on latitude, altitude, local time, and solar activity) • Only limited spatial resolution - up to the 8 th order of spherical harmonics • More data is needed to better describe small scale features (anomalies, enhancements, troughs, longitudinal dependency etc. ) • Better description of parameters depending on solar/magnetic activity variation especially during period of current very different solar cycles from those which were known during previous decades • It is important task to include independent Ti model COSPAR CBW 38