Plasmasphere Modeling

Shigeto Watanabe Hokkaido University http://www.ep.sci.hokudai.ac.jp/~shw/lecture/PlasmasphereModeling.pdf Why do we research Plasmasphere?

For TEC users, FORMOSAT ~800 km GPS ~20,000 km Galileo ~23,000 km GLONASS ~19,000 km BeiDou ~21,000 km NAVIC ~36,000 km Michibiki ~42,000 km IRI 2,000 km Photochemistry in the Earth’s Thermosphere

Photoionization Dissociative recombination O + hν → O + + e NO + + e → N + O + ν → + + + + → + O 2 h O 2 e O 2 e O O + ν → + + + + → + N 2 h N 2 e N 2 e N N Radiative recombination Charge exchange reactions + + → + ν + + → + + O e O h O N 2 NO N + + → + + O O 2 O 2 O + + → + + O 2 N 2 NO NO + + → + + N 2 O NO N + + → + + N 2 O 2 N 2 O 2 Earth’s Ionosphere and Thermosphere Photochemistry in the Earth’s Upper Thermosphere (Plasmasphere) Photoionization Charge exchange reactions + + + → + + + H + hν → H + e He N 2 N N He + + + → + + He + hν → He + e He N 2 N 2 He + + → + + + Charge exchange reactions He O 2 O O He O + H + ⇔ O + + H Radiative recombination H + + e → H + hν He + + e → He + hν

Gusev et al., 2003 Earth’s Ionosphere and Plasmsphere

Plasmasphere

Transition height

Ionosphere Plasmapause The location of the Corcuff et al., 1972 plasmapause depends on the magnetospheric Ne (cm-3) disturbance. Wave-like irregularity in the plasmapause results from transient, localized processes associated with substorms.

Plasmasphere Plasmapause Plasma is supplied continuously from Carpenter and Park, 1973 ionosphere. = − L pp 5.7 0.47 K p (Refilling) Magnetospheric Convection Solar wind

Velocity = 0 Plasmasphere corotates with the Earth. Plasmapause Magnetospheric convection Plasmaspheric erosion (plasma tail) is the result of enhanced magnetospheric convection. Magnetospheric Convection

= − × ( + ) E = − v × B E conv v sw B IMF B pol rot cor

Superimpose Plasmasphere and Plasma Tail The Earth’s plasmasphere is a torus of cold (~1eV) and dense (~10 3cm-3) plasma in the region of the inner magnetosphere. H+ is the principal ion with ~20% He +. From dusk From north cusp

plasmasphere

plasmapause IMAGE He+ (30.4 nm) Ion Composition

O+ ion density reaches values comparable to the H+ density in the region L=3-4. (Horwitz et al., 1984) Plasmapause

Ap (27) Ap (18)

Ap (12) Ap (5)

Spasojevie et al., 2003 Topside Ionosphere

Low latitude

Middle latitude

Why is low H+ density at high latitudes? High latitude (outside plasmasphere) Banks et al., 1976 Polar Wind Axford [1968] pointed out that the lighter ions must escape from the earth by the flux of escaping photo-electrons with energies greater than 2.4 eV, and suggested the ion escape speed of ~10 km/sec. This phenomenon is called ‘Polar Wind ’. The polar wind is important as a source of magnetospheric plasma [Shelley et al., 1982; Moore et al., 1986; Chappell et al., 1987].

H+, He+ flow Polar Wind Z Ambipolar Electric Field electron Refilling

O+ N Banks, 1972 Thermal Ion Outflow

Akebono/SMS Near magnetic pole, Abe et al., 1993 all ionospheric ions are flowing to Magnetosphere. Ion Outflow from Topside Ionosphere

Abe Ion Outflow Model from Akebono/SMS 2003/1/25 H+ Kp: 3 F10.7 : 125 Altitude: 6000km He + Northern hemisphere

Dawn

+ O Day Night

Dusk

Ne

Density Velocity Flux Ion Loss from polar ionosphere Suprathermal Ion Mass Spectrometer (SMS)

Watanabe, 2011 Akebono / PWS

Kitamura et al., 2009 Electron Density observed by PWS on Akebono Satellite

4,412,579 Electron Density Data Sets Arase Satellite Example of footprint (August, 2017)

- Launch: December 20, 2016 - Start of observations: end of March, 2017 - Apogee ： 32246 km (~6Re) - Perigee ： > 400 km - Inclination ： 31 deg - Spin Period ： 8sec - Orbital Period 563 min Arase (2017) Akebono (1989-2012) Hinotori satellites (1981-1982) ò Global Core Plasma Models (D.L. Gallagher, P.D. Craven, and R.H. Comfort) Plasmasphere, plasmapause, magnetospheric trough, and IRI model for ionospheric densities Seasonal and solar cycle variations ò Plasmasphere Models (Akebono Model) (Kutiev, I., K.-I. Oyama, S. Watanabe, T. Abe, and A. Kumamoto) Plasmasphere electron temperature ò IMAGE Model [info] (Huang, X., B.W. Reinisch, P. Song, P. Nsumei, J.L. Green, D.L. Gallagher) Empirical Models of the Plasma Density ò IZMIRAN10 (Chasovitin and Gulyaeva) From whistlers and satellites data Electron density smoothly fitted to IRI electron density profile at 1000 - 36,0000 km altitude. Solar activity and magnetic activity ò O'Brian and Moldwin (CRRES observations) Empirical models of the plasmapause location as a function of Kp, AE, and Dst ò European Space Weather Plasmasphere models for density (V. Pierrard & K. Borremans, BISA), density and temperature (V. Pierrard & K. Borremans), and the plasmapause (V. Pierrard) Day North Dusk Dawn Night Day Night South at 400km altitude

2/23 2/26 2/28 There are two approaches to make models, such as Physical model and Empirical model.

• Physical model: Powerful computer and lots of calculation times are needed.

• Empirical model: Lots of data and fitting terms are needed. Empirical Model of Plasmasphere along Local Geomagnetic Field Lines

, log = , , +

; Spherical harmonics , a, b = f ( Total Day, UT, Inv. Latitude, Magnetic Latitude and Longitude, Altitude, 5 days F10.7 and Ap ) Plasmasphere has long memory.

Fitting Parameters are estimated with Lease Square Method Plasmapause location is over 2Re, but density is decrease. Magnetospheric convection electric field may enter into plasmasphere. Deep Learning Model of Plasmasphere

Inputs: Input Satellite Datasets: Total Day Arase 312,599 UT Akebono 4,412,579 Hinotori 183,622 Latitude Longitude Altitude F10.7 ( 5 days data are used ) Ap ( 5 days data are used ) Memory effect is important in the plasmasphere modeling. Neural Network Model: 3 Hidden layers (1024x3 nodes) Total 3126 nodes

Output: Electron Density 2017 May 27 – June 1 TEC of Plasmasphere (>2000km altitude) 2017 Total day 146 147 148 149 150 2017 146 0UT 2017 147 0UT 2017 148 0UT

2017 149 0UT 2017 150 0UT Questions

• What is the detailed generation and loss processes of plasmasphere? • What is the energetics of plasmasphere? • What is the structure of plasmapause? • What is the generation mechanism of plasma density irregularity at plasmapause? • What is the coupling process between plasmasphere and geocorona? • What is the coupling process between plasmasphere and magnetospheric plasma? • What is the coupling process between plasmasphere and radiation belt? • What is the loss rate of the Earth’s plasma and the atmosphere? • Does the plasma loss contribute the evolution of the Earth’s atmosphere?