1. Solar Wind Propagation Tool Chihiro Tao 1,2, Nicolas Andre 1, Vincent Génot 1, Alexis P. Rouillard 1, Elena Budnik 1, Arnaud Biegun 1, Andrei Fedorov 1 1. IRAP, Univ. de Toulouse/UPS-OMP/CNRS 2. Now at NICT (chihiro.tao@nict.go.jp) Journée scientifique Juno/JUICE, IRAP, Toulouse, 13-14 October 2015 Session 5 : utilisation et développement des outils du CDPP pour Jupiter

2. Approaches BEST: direct solar wind monitor by a spacecraft (best, while it is not available at Jupiter) BETTER: direct solar wind monitor in cruising phase by Juno  comparison with remote observations. USUALLY: No solar wind monitor e.g., after Juno’s insertion into the magnetosphere  solar wind information predicted from models So far, main methods for predicting solar wind at planets are 0) Timing shift: 1) 1D MHD (HD) models: mSWiM, Our Model, … 2) 3D MHD models: ENLIL, SUSANOO, … Note that there is limitations/ambiguities in the solar wind models. Different weakness for 1D and 3D models.

3. Contents 1. Brief introduction of data-driven 1D and 3D models for solar wind prediction at planetary position 2. Recent updates in our models 3. Contribution and plan for JUNO

4. Solar Wind 1D Model OMNI (WIND) data input Inner boundary 1AU 5.2 (or 9.55) AU Outer boundary 8 (or 12) AU Spatial resolution ： 0.0033AU calc. time step:60-300 sec Sun Earth Jupiter/Saturn Data output 1) Input solar wind variation observed 2) Propagate the variation and output

5. Solar Wind 1D Model OMNI (WIND) data input 5.2 (or 9.55) AU Sun Earth Data output Jupiter/Saturn ESJ-angle ΔΦ Shift the time of solar wind output data for Δt = ΔΦ/Ωsun ΔΦ: ESJ-angle between Earth’s longitude at input time and Planet’s longitude at output time, Ωsun: solar rotation angular velocity. Assumption: Solar wind structure is conserved during solar rotation Weak for longitudinal limited structure as (i) short-time variation or (ii) CME, and also affected by (iii) off-equatorial structure Jupiter/Saturn Ωsun 1) Input solar wind variation observed 2) Propagate the variation and output 3) Correct ESJ-angle

6. SW1D Model Evaluation 1 Dynamic pressure [nPa] Ulysses obs. MHD output Good / Bad estimation events 1996 1997 × Caution!

7. SW1D Model Evaluation 2 time dynamics pressure Difference in arrival timing MHD Obs. Jupiter-Sun-Earth angle Δ Φ [deg] time difference [hours] Sun Earth Jupiter Ω 4.2AU ΔΦΔΦ

8. Solar Wind 3D Model 3D MHD model for space weather (ENLIL, SUSANOO, …) Input parameter *Solar surface magnetic field observation +Empirical models (B  V, T, N) @ ～ 25 Rsun [e.g., Arge and Pizzo, 2001; Hayashi et al., 2003] *Coronagraph observation  CME input Sun Solar wind Acceleration, heating MHD region Fig. V-N ＠ 50R sun, V-T relation taken by Helios observation [Hayashi et al., 2003] magnetogram CME Refers magnetic field at solar surface with empirical models.  They does not refer to solar wind observations

9. ENLIL Model Evaluation High stream enhancements predicted by WSA-ENLIL (note that no-CME model) output at 1 AU [McGregor et al. 2011] Hits: 155 Misses: 102 False HSEs: 38 Maybe more difficulty in density estimation, which affects dynamic pressure Good Bad Caution!

10. 3D (SUSANOO) Model Evaluation Comparison between modeled and observed SW at Earth  Less dependence on separation longitude Φ

11. Comparison between 1D and 3D Solar wind at Jupiter estimated by 1D (our) and 3D (SUSANOO) models, ~40 days

12. Solar Wind Models Strong: Direct input using solar wind data Weak: Bz and Bx estimation, longitudinal limited structure as (i) short-time variation or (ii) CME, and also affected by (iii) off-equatorial structure Strong: Longitudinal coverage Weak: Density estimation accuracy (which affect largely on dynamic pressure at Jupiter/Saturn)? Even difficulty in Bz estimation.

13. Recent Updates 1: Angle Correction 5.2 AU Sun Earth Jupiter ΔΦ Jupiter Ωsun *Calculate the propagation along the Sun-Earth line *Since both Earth and Jupiter move, estimation of ΔΦ = Φ(Earth, t_in)- Φ(Jupiter, t_out) contains assumption, we used ballistic propagation  larger error for longer propagation (i.e., beyond Saturn) *This correction sometime causes temporal reversal at fast-slow stream interaction  smooth-out with assumption BEFORE

14. Recent Updates 1: Angle Correction AFTER 5.2 AU Sun Earth Jupiter ΔΦ t_in Jupiter Ωsun ΔΦ t_out *Calculate the propagation along a reference longitude *Estimate longitudinal difference at input and output time separately ΔΦ = ΔΦ t_in +ΔΦ t_out 0 =Φ(Earth, t_in) -Φ(ref., t_in)+Φ(ref., t_out) -Φ(Jupiter, t_out) which does not require assumption to obtain time variation. *This does not bring temporal reversal Now we are evaluating this method and will reflect data in AMDA “reference longitude”

15. Dynamic pressure Radial velocity Plasma density Before / After This update does not change main profiles but arrival time ~ hours, under checking.

16. Recent Updates 2: Flexible Input/Output 5.2 AU Sun Earth Jupiter “reference longitude” STEREO In addition to OMNI  Jupiter propagation, Stereo  Jupiter/Juno Juno  Jupiter OMNI  Juno Solar surface  Jupiter/Juno … would be applicable. Juno

17. Contribution and Plan for Juno Juno’s cruising phase: *Propagate solar wind from Juno to Jupiter  [ADVANCED] Find/establish good indicator of solar wind in the Jupiter phenomena *Evaluate solar wind model Juno’s exploration in the magnetosphere: *Provide solar wind information for a reference