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IPS tomography IPS-MHD tomography. Since Hewish et al. reported the discovery of the interplanetary scintillation (IPS) phenomena in 1964, the IPS method.

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Presentation on theme: "IPS tomography IPS-MHD tomography. Since Hewish et al. reported the discovery of the interplanetary scintillation (IPS) phenomena in 1964, the IPS method."— Presentation transcript:

1 IPS tomography IPS-MHD tomography

2 Since Hewish et al. reported the discovery of the interplanetary scintillation (IPS) phenomena in 1964, the IPS method has been one of the few devices which can observe solar wind in three-dimensional space. Although the solar wind is extended radio scattering medium, old IPS analysis method assumed that the IPS observes the solar wind at a P-point where radio scattering is mostly weighted. However because of the line-of-sight integration effect of IPS, solar wind had to be studied with blurred images. In order to deconvolve the line-of-sight integration effect, Computer Assisted Tomographic (CAT) method was developed.

3 EISCAT 900 MH z 1420 MHz Long base line 90 km

4 After Breen et al., 1996 Baseline length 189 km Fresnel radius 90km

5 After Breen et al., 1996 Baseline length 239 km Fresnel radius 90km

6 Sun Earth ★ High-speed SW Low-speed SW

7 Lag time 0 Cross correlation Long base line observation Resolve into fast and slow winds

8 STELab 327MHz R F =150 km base line =100km EISCAT 930MHz R F= 90km base line = 380 km Since the baselines of STELab system are as short as Fresnel radius, STELab cannot resolve solar wind structure. However …..

9 Both solar rotation and solar wind outward motion provide us a large number of lines of sight, with which we can obtain perspective views of three dimensional solar wind structures. Using these large number of lines of sight, we can apply Computer Assisted Tomography for IPS analysis. This technique can retrieve not only unbiased solar wind parameters but also provides high spatial resolution.

10 Born 近似 SW In conditions of weak scattering, the IPS observations can be mathematically represented using the Born approximation in which the observed diffraction pattern is regarded as a weighted sum of contributions from each thin scattering layer perpendicular to the line of sight.

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12 Corotating tomography Time sequence tomography Two-spheres tomography MHD-IPS tomography Time-dependent tomography

13 Corotating tomography Synoptic map of one rotation Stable solar wind structure

14 Corotating tomography longitude

15 CT Analysis Corotating tomography

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17 Time sequence tomography Continuous synoptic map through a year Metastable solar wind

18 Time sequence tomography

19 Comparison of Ulysses and IPS Observations Red: IPS Black: Ulysses 1995 2001 Time sequence tomography

20 Two-spheres tomography R dependence of SW structure

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22 0.1 - 0.3 AU 0.3 - 0.9 AU 80 o 50 o 80 o 50 o

23 80 o 50 o 80 o

24 14 data sets

25 MHD-IPS tomography IPS observations are used as outer boundary conditions. Not only V and N but also T and B are obtained. Stream-stream interaction is considered. The analysis can be made beyond 1 AU even to heliospheric boundary.

26 5AU IPS CAT from SS to 1AU IPS-MHD CAT from SS to 5AU by Keiji Hayashi @ Stanford Univ. 1AU Time-dependent MHD simulation from 5 to 900AU by Haruichi Washimi @ CSPAR, Alabama Univ.

27 MHD-IPS CAT Simulation is started from the distance where the SW gets a final cruising velocity such as R>10 Rs. Inner boundary conditions T from an empirical relation with V, N from an empirical relation with V, B from observation and potential field model, V is determined by MHD-IPS CAT. Outer boundary condition IPS observations

28 Advantages for MHD simulation to collaborate with IPS. Simulation can starts from distance where SW acceleration is almost completed. Simulation can use IPS observations as outer boundary conditions.

29 MHD simulation Hayashi et al.

30 0.25AU 1 AU NV Hayashi et al.

31 3 D MHD Tomography

32 IPS-MHD Tomography Spacecraft observations

33 Ulysses IPS- MHD B T N V MHD-IPS CAT can obtain solar wind structure at any distance form the sun. Comparison with Ulysses observations in1995 ~ 1998 Hayashi et al.

34 Time-Dependent MHD Simulation By Hayashi and Washimi  Period: 2001.1.1-2009.12.31  Simulation Box: 5-900AU  Inner boundary: IPS-MHD tomography map at 5AU by Hayashi  outer boundary(LISM): N p =0.061/cc N H =0.176/cc T=6300 K B LISM =4.8μG (distance of TS crossed by V1) B LISM =(225 o,45 o ) in ecliptic coordinate V LISM =26.3km/s  Solar Wind: Density variation of SW: 5.0/cc (2005)  3.5/cc (2008) linear interpolation  Mutual charge exchange (PUI)

35 km/s Global Picture Of Heliosphere boundary of Flow 2009/12/31 LISM Turbulent flow B LIS

36 Time-dependent tomography ICME

37

38

39 Weighting = IPS weighting x estimation error x angular distance

40 LOS Sun slow fast slow fast V V Longitude


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