Extremely intense ionospheric ion escape during severe ICMEs:

Transcription

1 Extremely intense ionospheric ion escape during severe ICMEs: Space Weather Events triggers massive escape more than any empirical model predicts M. Yamauchi 1, A. Schillings 1,2, R. Slapak 2, H. Nilsson 1, I. Dandouras 3 1. IRF, 2. LTU, 3. IRAP, U. Toulouse/CNRS, Toulouse, France 1

2 Key Point (1) Slapak et al. (2017): Ion Loss Rate from the Earth for Kp < 7 : F µ exp(0.45*kp) Þ F kg atmospheric O 2 (2) Yamauchi and Slapak (2017): Extraction of Solar Wind kinetic energy by mass loading : E µ F v SW 2 (3) Schillings et al. (2017): However, for large Kp 7+, F (and E) >> prediction by exp(0.45*kp) Þ Space Weather Events plays some role in O+ escape 2

3 (1) O + escape vs. Kp: low-altitudes Suprathermal H + & O + < 70 (Akebono) Highest flux = polar region Þ might mix with the solar wind (Cully et al., 2003) 3

4 (1) O + escape vs. Kp: Cluster/CIS Cluster could distinguish (a) and (b) 4

5 Cluster/CIS hot O + obs. of direct escape 10 26??? Kp ~ 0.7x10 25 s -1 R ~ 2x10 25 s Ion Loss Rate : F µ exp(0.45*kp) Cluster/CIS: (Slapak et al., 2017) Kp # samples X 5

6 (2) Feedback from escaping ions total velocity V [km/s] Total velocity along the flow O + H + O+ escape rate: F µ exp(0.45*kp) (Cluster data: ) (dayside) Latitude (nightside) V Parallel velocity along the flow O+ increases while V H+ decreases Þ Mass loading Þ inelastic momentum conservation Þ Extraction of kinetic energy 6

7 (2) Feedback from escaping ions MHD dynamo during deceleration (1) Amount is substantial: n O+ /n SW ~0.01 Þ r O+ /r SW ~0.16 Þ extract 7% of kinetic energy Þ W to J // through B 7 without outflow Solar Wind Z ξ exterior cusp proton electron J // η B E with outflow final + + E + J // B B Ionosphere

8 (2) Feedback from escaping ions Extraction of kinetic energy: E Simple conservation laws: Þ E µ F v SW2, but nothing else Since F µ ionospheric current µ E Þ Positive feedback between E µ F v SW2 & F µ exp(0.45*kp) MHD dynamo during deceleration without outflow Solar Wind Z ξ η exterior cusp proton electron J // B E with outflow final + + E + J // B B Ionosphere 8

9 (2) Feedback from escaping ions Extraction of kinetic energy: E Simple conservation laws: Þ E µ F v SW2, but nothing else 10 4 Kp vs. energy extraction rate ( K) enhanced positive feedback? Since F µ ionospheric current µ E Þ Positive feedback between E µ F v SW2 & F µ exp(0.45*kp) Þ E µ Kp 2 exp(0.45*kp), for Kp<6 We expect nearly linear relation between Kp and log( E) But, reality for Kp>7 is. 9 K (relative value) Kp estimate by mass-load model

10 (3) Non-linearity for Kp>7 example: Halloween event ( ) O + energy H + pitch angle O + (>0.3 kev) O + (<0.3 kev) 10

11 (3) Non-linearity for Kp>7 Shift of median flux example: Halloween event ( ) entire Flux after scaling to the ionosphere Reference: 1-year data in the same region 11

12 (3) Non-linearity for Kp>7 Examined total 6 extreme events Dates V SW (km/s) N SW (cm -3 ) Dst [nt] Kp ~ ~ ~ (2000?) ~ ~

13 (3) Non-linearity for Kp>7 Shift of median flux (a) Southern hemisphere x 47 x 50 x 10 x 18 13

14 (3) Non-linearity for Kp>7 Shift of median flux (b) Northern hemisphere x 20 x 6 x 9 x 60 x 83 x 18 14

15 (3) Non-linearity for Kp>7 The O + outflow during major storms is 1 to 2 orders of magnitude higher than during less disturbed time 15

16 Summary and Conclusion (1) Slapak et al. (2017): Ion Loss Rate from the Earth for Kp < 7 : F µ exp(0.45*kp) Þ F kg atmospheric O 2 (2) Yamauchi and Slapak (2017): Extraction of Solar Wind kinetic energy by mass loading : E µ F v SW 2 Þ E µ Kp 2 exp(0.45*kp), for Kp < 7 (3) Schillings et al. (2017): However, for large Kp 7+, F (and E) >> prediction by exp(0.45*kp) Þ Space Weather Events plays some role in O+ escape & F >> kg (atmospheric O 2 ) Þ Space Weather Events plays important role in atmospheric evolution 16

17 Future direction Need to understand neutral escape too. Þ ESCAPE mission (oral later) 17

18 End / extra slides 18

19 (2) Feedback from escaping ions Extraction of kinetic energy: E Simple conservation laws: Þ E µ F v SW2, but nothing else Since F µ ionospheric current µ E Þ Positive feedback between E µ F v SW2 & F µ exp(0.45*kp) Þ E µ Kp 2 exp(0.45*kp), for Kp<6 & IMF B Y effect can be explained 19 (a) B Z <0, B Y =0 10 MLT O + R1-sense O + H + O + O+ O + 12 MLT O + O + O + Mantle e - O + ξ=x Z O + O + 14 MLT η=y R1-sense (b) B Z <B Y 10 MLT 12 MLT H + 14 MLT e - magnetopause R1-sense O + Mantle/Lobe O + O + O + O + O + O + R0-sense O + O + O + O + Z ξ X magnetopause η Y

20 (2) Feedback from escaping ions # data points total velocity V [km/s] Since F µ ionospheric current µ E Þ Positive feedback between E µ F v SW2 & F µ exp(0.45*kp) Þ E µ Kp 2 exp(0.45*kp), for Kp< x x x Total velocity vs Kp in the outflow path (Cluster data: ) plasma mantle Kp O + H + 20 K (relative value) Kp vs. energy extraction rate ( K) enhanced positive feedback? estimate by mass-load model Kp

21 Method-2 29-Oct-2003 (sc4) 2 nd step: Plot the boxes and look at the plasma beta 29 Oct 2003 Halloween event GSM Z [R E ] Col. sc.: Log 10 plasma beta Col. sc.: Log 10 O + total flux GSM Y [R E ] GSM X [R E ] GSM X [R E ] 8 A.Schillings 21

22 Method-3 Year 2003 Scaled O + flux log 10 m -2 s -1 Number of data points 3 rd step: Check the plasma beta parameter for the O + outflow during the year A.Schillings Log 10 plasma beta GSM R [R E ] Colour scale: Log 10 plasma beta (sc4) GSM X [R E ] Log 10 22

23 (1) Slapak et al. (2017) Cluster observations in the magnetosheath and plasma mantle show, Ion Loss Rate from the Earth : F µ exp(0.45*kp), for Kp<7 Þ This already gives total escape over past 4 billion years F kg present atmospheric O 2 (2) Yamauchi and Slapak (2017) Inelastic mixing of escaping ions with the solar wind (i.e., massloading) converts solar wind kinetic energy to electric potential energy, which is consumed in the ionosphere because of direct geomagnetic connection. Conservation laws predicts, Energy extraction (total) : E µ F v SW2, but nothing else. Þ Positive feedback between the ion escape and energy extraction transfers the non-linearity (to Kp) from F to E, Ionospheric/Ground current µ E µ Kp 2 exp(0.45*kp), for Kp<6 (3) Schillings et al. (2017) However, for large Kp, the flux values F is much higher than the prediction by (1), but more than one order of magnitude. F >> kg present atmospheric O 2 Key Point Þ Space Weather Events plays some role in atmospheric evolusion 23

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