Инжекции плазмы на геостационарную орбиту: зависимость от параметров плазменных струй и состояния магнитосферы. V. A. Sergeev, I. A. Chernyaev, S. V. Dubyagin (SPbU), Y. Miyashita (STEL), V. Angelopoulos(UCLA), P. D. Boakes, R. Nakamura (SRI,Graz) M. Henderson (LANL)

Т Е М А Связь струйных течений в плазменном слое магнитосферы (BBF) с инжекциями энергичных частиц на геостационарную орбиту o Модели и Наблюдения o Модель плазменных струй (“bubble”) o Эксперимент: сравнение BBF  инжекции, роль величины энтропии плазменной трубки o Факторы, контролирующие глубину инжекции, прогноз возможной инжекции для GEO

Transient Injections into the inner magnetosphere - theory/simulations  Subsonic EM pulse model ( Li et al.1998, Zaharia et al., Sarris et al. ) - useful mathematical model, but - EM pulse origin is unclear  Plasma bubble model ( Pontius and Wolf 1990, Chen and Wolf…, MHD simulations Birn et al RiceU group, reviews by Wolf et al.2009, Birn et al )  Bubble =plasma-depleted dipolarized fast-flow channel in closed flux tube region  Origin either (1) Magnetic reconnection  production of low-entropy bubbles ( Birn et al. JGR2011 ), or (2) Interchange instab. in minB configurations (… Pritchett &Coroniti, 2011 )  modest depleted tubes  pV 5/3 in the bubble as important parameter, e.g., injection depth ( Birn et al., 2009 ) Equatorial view (Birn et al., JGR 2011)

Plasma Bubble Scenario  Plasma tube entropy S  P V 5/3 (V=  ds B) - approx. invariant in the moving flux tube (exact in frozen-in plasma, ideal MHD) ??  Polarization/FAC generation if  S  V  0 (from Vasyliunas- Tverskoy theorem), j  i = B i /2B eq z  [  V  P ] eq = B i /(2B eq V 5/3 ) z  [  V   (PV 5/3 )] eq.  S provides integral measure of divergence of perpendicular plasma current  If cross-tail  S exists, polarization  radial interchange motion  Depleted plasma tube (bubble) moves Earthward (BBF)  Generator for MI coupling  R1-type FAC, FA acceleration, streamers …(many evidence…)  Final destination (R 0 ) depends on bubble entropy Sb ( Birn et al., 2009 ) ??

Transient Injections into the inner magnetosphere - observations Observationally the relationship BBF/DIP  injection/DIP is not as obvious:  BBF braking/rebound/diversion is not well understood, but sometimes expected to operate at ~10 Re, e.g. Haerendel, Shiokawa … -. Probability of Earthward flow sharply decreases 9  7Re ( Lee et al., 2011 ) injections to 6.6Re?)  Considerable part of BBFs do not produce injections  2-SC comparison : Low penetration efficiency of BBFs (~30%, CL- TС1, dr~5Re,Takada et al )  Many BBFs do not produce DIP/injection at GEO ( Ohtani et al.2006 )  Many substorm onsets are not accompanied by GEO injections (30% in Boakes et al ). It is not sufficient to create fast flow channel, there should be another factors/processes (another physics) which control the inward penetration of plasma (injections). ROLE of Bubble ENTROPY !

Motivation of this talk  Test observationally two basic predictions of the bubble scenario concerning GEOinjections Penetration distance depends on bubble S b Possibility of injection is controlled by S 0 at destination place  Requirements Registration in 2 points : inside flow burst and at GEO (injection) Computation of S=pV 5/3 at both locations Equatorial view (Birn et al., JGR2011) Tail configuration: stretched quiet

Plasma Bubble Scenario - Validation?Questions  How to evaluate V=  ds B in Flow Burst based on SC observations?  Formula by Wolf et al. (2006) for V (x,y,Br,Bz,P) - by fitting many equilibr. configurations  Tested/validated in 3d MHD simulations Birn et al.(2011)  How to compute V & P, S at GEO??  Using SW-based model (T96), V – directly from T96, P –from integration P GEO =  dx (jxB) x + P 11Re. (Tsyganenko-Mukai 2003 pressure model)  Validity of PV 5/3 =const, esp. in the inner region magnetic drifts?, turbulence?  How does the entropy change during dipolarizations in the inner region?  Entropy (etc) change during dipolarizations in the inner region?

Experimental Setup & Data Base #1 Geotail ( 8-12 R E, +/- 3h MLT )  LANL ( any MLT ): ~60 with definite LANL events Isolated Flow burst/DIP at the tail probe dBz>5 nT,  >1, … #2 THEMIS (~11R E, +/- 3h MLT)  THEMIS (~9R E ) radial pair THEMIS (~11R E, +/- 3h MLT)  LANL (any MLT, blind test)): ~50 events (Dubyagin et al. GRL 2011) same as before at the tail probe  Entropy S at tail probe - use V (p,x,y,Bx,Bz) from Wolf et al 2006  Entropy at 6.6Re, 02 h MLT calculated from SW-based T96 model No injection Injection GEO Tail configuration: stretched quiet

#2 THEMIS pair: Examples, Flow Bursts as the bubbles P3 P5 P3 P5 Injection No injection ~20% 8 events 11Re  ? ~80% 34 events 11  9Re

#2 THEMIS pair : Entropy Test, 11  9 Re peak Vx or  Bz at tail probe are bad predictors Entropy is best predictor of penetration to inner probe, still works in drift-dominating region (Dubyagin et al GRL 2011)

#1 Geotail  LANL : Flow Bursts as the bubbles Superposed Epoch results (1min averages) Common for bubbles/BBFs ( e.g., Ohtani et al 2004 )  Enhanced BZ, flow VX, flux transport Ey O  Depleted pV 5/3 Peculiar at ~9Re are  density/pressure depletion - less clear (1min?)  entropy control works 11  9Re (THEMIS) GEO-penetrating flow bursts  Deeper |  S| depletion and larger dBZ in penetrating FBs  Vx or Ey are bad predictors  Higher pressure before/during penetrating FBs – effect of background configuration

#1 Geotail  LANL : Radial Dependence GEO-penetrating flow bursts have  Deeper |  S| depletion and larger dBZ  Higher pressure before/during penetrating but:  Sb ( r ) ! (drifts?, systematic errors in S-computation?)  Nearest flow bursts are more effective ! %

Does penetration depend on how stretched configuration is? Entropy at 6.6Re, 02 h MLT calculated from SW-based T96 model (+TM03 pressure)  Confirm that injection probabilty strongly depends on how stretched is the local configuration (in agreement with Takada et al. 2006, and Boakes et al.2011 results)  Suggest local entropy S GEO as convenient local parameter controlling the penetration distance (together with bubble entropy Sb)  Confirm the basic predictions of the bubble scenario InjectionNo injection Tail configuration: stretched quiet

CONCLUSIONS Generally confirm flow bursts (BBF) as origin of transient injections to GEO  Direct support of “bubble” model (BBF) Statistically Vx, dBZ   S at ~11Re Injection 11Re  9 Re predicted by S b /S in !!  Conditions for GEO injections Penetrating injections have lower S b Vx or Ey – not important factor Critical dependence on Configuration at destination place ( local S in )!!  Practical way to predict - based on local S in  GEO injections are not a reliable signature of substorm onset

Dec.16, 2006

Interpretation of R2 loop : MHD, RCM R2 R1 Generation of R2 currents during flow braking/diversion Birn et al., JGR 1999, 2011; Yang et al Question to modelers : quantitative relationship I 1 / I 2, its variations Courtesy J.Yang RiceU

BBFs as spatial structures Pre-Cluster view: true convective flows in the CPS (plasma tube motion); time-scale 1- 10min; basic contribution to PS transport; strongly related to SBS; may be MReconnection product cross-tail scale ~2-3 Re – confirmed statistically by Nakamura et al. (2004 GRL, CL) bubbles (turburlence?) Runov et al., GRL 2009; PSS 2010 TH (also Tang et al.,2010) BBF at SBS onset traveling 20Re  11Re ( ) BBF as individual meso-scale structure (not turbulence) conserved/ transported on macro- scales (~10Re, minutes) Generic structural features : laminar compression layer, sharp DIP front, bubble proper (turbulent inside) ;  BZ, (T )  N, P, PV   plasma bubbles; V front ~ V px ~ 300km/s, ?reconnection in embedded TCS? Consistent with statistical BBF properties ( Ohtani et al.,JGR 2004, GT)