Magnetospheric Interactions with the

Transcription

1 1999 CEDAR Workshop Boulder, Colorado June 13-18,1999 Solar-Terrestrial Coupling Processes Tutorial Lecture II by Larry Lyons University of California in Los Angeles Magnetospheric Interactions with the Solar Wind and Ionosphere

2 Interplanetary Sources for Geomagnetic Activity General Convection: IMF Bz, By effects on strength; response to IMF changes Tail plasma source: dependence on convection strength? Strong convection: Earthward penetration of plasma sheet and resulting large distortion of B Geomagnetic disturbances: Characteristics of, distinctions between types, relations to interplanetary conditions. Poleward boundary intensifications Substorms Convection bays Storms, including newly discovered response to pressure pulses

3 I MAGNETOPAUSE CURRENTLAYER

4 AE-Cl-0 Fig r Vl.lmVmV* Total transpolar voltagelneas'ured by foumow-altitude spacecraft plotted versus simultaneous vbt in the solar wind (from Cowuey, 1984). 8,. fc/> i/* ** ^A

5 Convection Strength Increases as IMF Bz becomes Increasingly negative (well know) Also increases significantly as IMF IBVI increases (not as well studied) AMIE results for GEM stable IMF periods [G. Lu] Bx (nt) Bv(nT) B2 (nt) N. h m. A4> S. hem. AO kv 20 kv kv 80 kv kv 74 kv kv 25 kv

6 sw Width of open region W = A< >/(Vsw x Bimf) ~ 100 kv/(400 km/s-5 nt) -8 Re Length ofopen region L ~ 0/(Bimf#W) Re Open magnetic flux < ~ 7 x 108 T-m2

7 1992 Jan 28 19:05 UT +/- 45 min Bx =7.6 / By = Bz = 6.8 Northern hemisphere &t<»*okv Separatrix Separatrix? Flow direction P3 TOIL 1820 ^ Southern -x hemisphere \i828f10 4+ ~Xo\t.V F9 * i /H1 /1943 Figure 8

8 1992 Jan 27 15:20 UT +/-115 min Bx = 5.1 F11' "* w"' 1403/ By =-19.7 / Bz = 6.5 Northern hemisphere F10\ 1309V 1450V 1630V /1406 '1550 Separatrix Separatrix? F8 y =*r Southern hemisphere 1453 '1633

9 1992 JUL 20 20:15 UT*7*''" Bx,y= 1.9, 13.1 Bz= 1.1 MH I 6 \io 50 y \ ELECTRIC POTENTIAL &$*- si kv * ; - ]bfe 1992 JUL 20 20:15 UT -»** «12 Bx,y= 1.9, 13.1 Bz= 1.1 MH I 6 08/16/94 UTITED) CONTOUR FROM -asaee. to 3eeee. contour interval of tt»t(3.3»<

10 1989 Jan UT Bx~7 By ~0 Bz~0 / / Northern F9 hemisphere P502 s^644 N0320 \0140 &$<*tskv 18 Plasma sheetpolar rain boundary O C Inner edge soft electron zone Plasma sheet-cusp boundary warn Cusp/mantle «ww Soft electron zone &&& Intermittent weakps polar-cap arcs 190J Polar-cap arc / 2051 t60 Southern hemisphere v. 0334V F9 ry2311 r ^

11 BGSM BzGSM ByGSM BxGSM *- OO K> K> O * OO K> K> BGSM BzGSM ByGSM BxGSM ^ "* (* 9

12 1188 GILBERT D. MEAD Z 116**] J 1 L PURE DIPOCE DISTORTED WPOLE Fig. 4. Field line configuration in the noon-midnight meridian plane. With rb = 10 earth radii, the critical latitude is about 83. The dipolc lines are compressed on both the daytime and nighttime side.

13 ?i\ipf> ctw MnCill C117*1 JuLL' St?hcmlat,f J1'?""" f the tran*p0" of mantle plasma onto the plasma sheet under the influence of the largescale convection electric field. The mantle particles disperse and move along the dashed lines. Mantle plasma entering the field reversal region within the neutral point' becomes trapped and forms the plasma sheet. The magnetic field (solid lines) is depicted as an instantaneous snapshot of the quiet time configuration. For average Afaaii - 50 kv ~ 2.7 hrs to move -15 Re from mantle to current sheet (tail width = 50 RE, B 0be = 15 nt) Only particles with V < 67 km/s reach current sheet earthward of X-line (x =-100 RE) Small fraction of mantle particles, since Vmantle ~ 150 km/s ForA< >taii~120kv hrs to reach curent sheet; particles with Vj <160 km/s enter earthward of X-line Much larger fraction of mantle particles have access Potential for greatly enhanced cross-tail current when have strong convection for >~1hrs (storm conditions)

14 (^..!"! 0^or 10- $ 0 Yama»otoetal. P^ ww v GSM-X' Figure 3. Magnitude of magnetic field in the XY plane as a func tion ofx\ The empirical curve by Slavin et ai [1983] is drawn as a reference.

15 GEOTAIL

16 November 27, MLtV> t UT 700 M &SM -4-9 Dst CO -20 r Q-40 i- :...,... i.. -6Q Day, November i... = 30

17 IMF effects strength of convection and probably solar wind plasma access How does this lead to geomagnetic activity? Get enhanced'«me within tail andlonosphere High (3 of plasma sheet greatly modifies B Get enhanced plasma and magnetic energies Largest plasma pressure and B changes at r ~ 6-10 RE Due to earthward motion of plasma sheet driven by enhanced E

18 20 M*V/G (-20 kev r = 7 Re) Equatorial Proton Trajectories Magnatopausa -A4 ~ 100 kv A< > - 30 kv 12MLT 24MLT 10 18MLT RE

19 Ion Energy (kev) o Electron Energy (kev 73'^pC H Ion Energy (kev) -j o Electron Energy (kev) o _> s*b 8 vc o ^1* O ooi->o en H

20 10 Pre-onset conditions CO Q. c Kistleretal.[1992] CD v- co CO o Q. 'l. o "3 CX LU 0.1 Spence et al. [1989], Kp = Radial Distance, Re

21 5 5: uu> Aa cuo Za

22 Geomagnetic Disturbances: Identification; relation to plasma sheet Plasma sheet ions, electrons pitch-angle scattered and precipitate Resulting auroral emissions excellent for identifying geomagnetic disturbances & determining relation to time evolution of plasma sheet Will use data from CANOPUS meridian scanning photometers. Hp emissions (proton precip.) Identifies & locates ionospheric mapping of inner plasma sheet 6300 A emissions (< ~1 kev else, precip.) Identifies & locates latitude range of plasma sheet electrons Poleward edge locates ionospheric mapping of separatrix (+/-1, Blanchard et al. [1996]) 5577 A emissions (> -1 k V tec. precip.) Identifies & locates auroral disturbances associated with geomagnetic activity

23 o o Q D Eh M O 2 O o O en

24 invariant latitude [6eg\ O) O) O) Nj N Sj Nj ^ O) OJ O M A O) invariant latitude [degj cd cd cd -vj -vj -^j ->j a en a> o m a O) invariant latitude [deg] u ' angstrom intensity [Ra] -^ ro co -t^. CD CD CO 5577 angstrom intensity [Ra] -^ -^ M CO Ol nj cr co» -vj 4^. en ro en 7;.v, -o _l -^ (o O 4> 6300 angstrom intensity [Ra] -> ~* ro ro ^cnrocx-^oioo) oroooco-sicooro

25 18 December :00 04:00 06:00 08:00 10:00 12:00 s 70 6S * ao S H } 6S to 66 * 64 J" 76 =- 7A H 6B «66 = e e to 12 RANK ESKI FCHU BACK GILL ISLL PINA,. AX A }200nT :00 04:00 06:00 08:00 10:00 Universal Time [hr] 12:00

26 12 January 1991 RANK ESKI FCHU BACK GILL ISLL PINA 02:00 04:00 06:00 08:00 10:00 Universal Time [hr] 12:00

27 12 February universal time [h]

28 January 18, A poleward boundary i24 MLT RANK ESKI FCHU GILL AX -1'^_ 124 MLT "_ IL~^- -. ^_y ^^_s~. ^ --_, - - ^ ' " -""" nt I A Pi 2.. rank /yvvvwwmjm/ym jw^ - ~^rv*~»^w<. ~- 25 nt A Q\\ I ^;\/vv-^" '-^ll^v./v/lj,^-/.jvvv^;^m^^^a^\^^^a/^a.^/^-fcv^-.^vv-.' <-._-*-,-"-. -v'-.^v.--^ v _,.-.._-.-^.. ikw^/vs/vv- *<i^^< 67 04:00 05:00 06:00 UT(hr) 7:0 08:00

29 0G20 i r in cnso \\ 1 / //. - i r A \ \ /^ / /0\ \ i / ^ - ^>^ J 1 y ^ ^, _ /X\ i A 1 i 2 L s/udj i < i ' «' 92Z 5 O m oez S 9*ez > 5 o*z<2

30 Poleward Boundary Intensifications (PBIs) Active aurora initiates near separatrix, can then move equatorward. Very common, individual events often <10 min apart. Occur during all levels of geomagnetic activity. Generally brightest feature in auroral zone Associated few min flow bursts Equatorward in ionosphere [Sergeev et al., 1990; de la Beaujardiere et al. 1994] Earthward in tail (i.e., BBFs) [Lyons et a., 1999] PBIs not associated with substorms have clear preference for radial IMF [ZestaetaL, 1998] Related to enhanced magnetosheath turbulence from quasi-parallel bow shock?

31 IMP 8 24 January 1991 At -3 02:00 04:00 06:00 08:00 10:00 12:00 RANK ESKI FCHU BACK GILL ISLL PINA 02:00 04:00 06:00 08:00 10:00 Universal Time [hr] 12:00

32 13 December 1990 RANK ESKI FCHU BACK GILL ISLL PINA 02:00 04:00 06:00 08:00 10:00 Universal Time [hr] 12:00

33 WIND January 10, UT at nose 20

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36 . to i i i i I r i i i 6300 angstrom intensity [R] JWUiO -'to-^cocncdcoo rococnroj^^-cd-ti-cd-nio Inv. Lat. CJ> CJ> CD -vl A en cd o Inv. Lat. O) CO o s ^. CD CO o Inv. Lat. CD CD CD O) -v ~~J --J Inv. Lat. Inv. Lat. O) -i -J CD 01 o 01 o ai en, i i i i i i Inv. Lat. - to f-m I m Ii i i i 4861 angstrom intensity [R] 5577 angstrom intensity [R]^ ** S Q 4». en co o CO -vj -» o 6300 angstrom intensity [R] a co * S <D i> Ui O) ID 4861 angstrom intensity [R] -* -^ ro ro u roiocoj^cdcorocn-'cdo 5577 angstrom intensity [R] -" W U O) -»rococ»ro-icoco MQO)-'On njoo)$(d ocn-fc>.cncd^ro-v4cdcncd

37 MAGNETIC FIELD TOPOLOGY 27 OCTOBER 1992 I,,:A -I -'!.,"f UNCONNECTED OPEN UT CLOSED 0545 UT -30- '"n- Z,RE ~t i i r Y, RE i i i r ~i i i r Y. R, t i i r

38 IMF Measurements with Multiple Monitors Good Correlation i i i i i i i i i I i i i i i I i i i i i I i i i i i I i i i i i : 5/5/96 WIND(66,21,1R.) IMP (1,35,-4 RJ ; j i i i i i i i i i Poor Correlation I I I I I I I I U I I I I I I T I I r 5 7 Est. Magnetopause Contact UT (hr) ' GT (15, 24, 3R,) E IMP (3,-34, 2 R ) - " I IE.. I I li i ^ I i i i i i' 5 7 Est. Magnetopause Contact UT (hr) O.K. Correlation CD 12/19/96 i I i I r Poor Correlation I i i i i} i i i i i i i i i i i i i i H IMP (-4, 26, 29R ) WIND (174, -18,6 R ) : -GT(-18,20,5R.shealh) " i» I i >. I.. 5 I i i I il i i i i I i i i i i i Est. Magnetopause Contact UT (hr) 1.1, i. i,i I. i i i i i I i ni \ I i i i i i I li i i i i i i i i i r 3 5 Est. Magnetopause Contact UT (hr)

39 SUMMARY General Convection IMF Bz and By control strength Response to IMF changes rapid throughout polar cap Tail plasma source Significant dependence on convection strength strongly affects tail? Strong convection Gives earthward penetration of plasma sheet and associated large distortion ofb Of major importance to substorms, convection bays, storms Important consideration for studying interplanetary sources for activity IMF structure in plane perpendicular to Vsw

40 Geomagnetic disturbances: Poleward boundary intensifications (PBIs): All levels ofactivity Associated few min flow bursts (equatorward ionosphere, earthward tail) PBIs not associated with substorms have preference for radial IMF Substorms: Follow > 0.5 hr ofenhanced convection (negative IMF Bz) Growth: earthward plasma sheet penetration, tail energy enhancement Onsets often (at least?) assoc. with IMF changes that reduce convection Initial predictions using such IMF changes successful [Blanchard et al., 1999] Convection bays: Prolonged periods of steady enhanced convection Plasma sheet, tail B like end of substorm growth phase, but -steady state Activity dominated by large PBIs, substorms (if any) much less significant Storms: Prolonged periods of strongly enhanced convection Plasma sheet and geomagnetic activity like during convection bays Also global auroral, current enhancements from interplanetary dynamic pressure enhancements?