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Global Properties of Heliospheric Disturbances Observed by Interplanetary Scintillation M. Tokumaru, M. Kojima, K. Fujiki, and M. Yamashita (Solar-Terrestrial.

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Presentation on theme: "Global Properties of Heliospheric Disturbances Observed by Interplanetary Scintillation M. Tokumaru, M. Kojima, K. Fujiki, and M. Yamashita (Solar-Terrestrial."— Presentation transcript:

1 Global Properties of Heliospheric Disturbances Observed by Interplanetary Scintillation M. Tokumaru, M. Kojima, K. Fujiki, and M. Yamashita (Solar-Terrestrial Environment Laboratory, Nagoya University)

2 Interplanetary Scintillation (IPS) Measurements as a Tool for Studying Global Properties of CME in the Solar Wind Sun Earth CME Radio Source Shock IPS observations enable to probe multiple points in the solar wind in a relatively short time. (SOHO/LASCO) 3D structure and propagation dynamics of CMEs between the Sun and the Earth orbit are mostly obscure. Propagation direction?, Angular Extent?, Speed evolution? Sun White Light Image of Solar Corona Coronal Mass Ejection (CME)

3 STEL 327-MHz Four-Station IPS System SWIFT Kiso antenna Fuji antenna Sugadaira antenna Toyokawa antenna Aperture Size: A ~ 2,000 ㎡ N~40 sources/day Measurements Solar wind speed Scintillation disturbance factor (g-value)

4 SOHO/LASCO Projection map of g-values between 2000/7/11:22h UT and 7/12:7h UT Interplanetary CME identified from STEL IPS Measurements g>1 → Excess of ΔNe The g-value represents the relative variation of scintillation level Δ S ; i.e. solar wind density fluctuations ΔNe (Gapper et al., 1982). STEL IPS observations: Frequency: 327 MHz No. Sources: ~40 sources (ε<90 deg) in a day G-value enhancements are ascribed to interplanetary CMEs.

5 IPS Observations of an Earth-Directed CME (the 2000 Jun 6 halo CME event) Observed g-value map LASCO CME Image Earth-directed CME

6 Retrieval of 3D Structure of Interplanetary CME by Model Fitting Analysis Earth Sun ΔNe Model Observed g-map Line-of-Sight ΔNe: Density fluctuations K: Normalizing factor w(z): IPS weightening function z: Distance along los q: Spectral index Ψ: Apparent source size λ RF : Observing wavelength Search for the best-fit parameters Sun Earth (Cf. Tappin, 1987)

7 ΔNe model – Enhancement Component - Ecliptic Plane Enhanced ΔNe region (ICME) EarthSun Radial Distance ΔNe e-folding thickness D θ : Separation Angle T lapse : Lapse Time after Lift-Off V S0 : Ave. Transit Speed C 0 ( ≒ 1) C1C1  Radial Expansion (Const. Speed)  Solar Rotation (Cf. α =2 Smart & Shea, 1985) ΔNe of the ambient solar wind is assumed to distribute as R -2.

8 Global Feature of CMEs in the Solar Wind 1999 Sep 20 event 2000 Jul 10 event 2000 Jun 2 event 1999 Aug 17 event 2000 Jul 14 event 1999 Apr 13 event 2001 Aug 25 event

9 3D Reconstruction from IPS and White-light Observations for 2003 October 28 CME Event 3D Reconstruction from IPS and White-light Observations for 2003 October 28 CME Event Propagation Speed Estimated from IPS: 1,083 AU Cf. Shock Transit Speed: 2,186 STEL IPSSolar Mass Ejection Imager (SMEI) SMEI-IPS Correlation (by B.V. Jackson) Correlation Coefficient

10 Radial Variation of CME Speeds CoronagraphIPS In Situ (M. Yamashita, D. thesis) Propagation speeds of ICME were derived by fitting a shell-shape model to IPS data.

11 Deceleration of Fast CMEs We fit a power law function R a to the deceleration profile of CME speeds in the solar wind frame. We fit a power law function R a to the deceleration profile of CME speeds in the solar wind frame. The slope of radial fall depends on difference between initial CME speed and ambient flow speed. The slope of radial fall depends on difference between initial CME speed and ambient flow speed. Interaction between CME and the ambient SW plays an important role Interaction between CME and the ambient SW plays an important role Cf. Drag force model (Vrsnak & Gopalswamy, 2002). Cf. Drag force model (Vrsnak & Gopalswamy, 2002). M. Yamashita, D. thesis Power-law Index

12 Summary STEL IPS observations were used to study global feature and propagation dynamics of CMEs in the solar wind. STEL IPS observations were used to study global feature and propagation dynamics of CMEs in the solar wind. Our results suggest that Our results suggest that Some CMEs observed in the solar wind exhibited loop-shape distribution, and some had shell-shape distribution. Some CMEs observed in the solar wind exhibited loop-shape distribution, and some had shell-shape distribution. There are two possible origins for g-value enhancements. There are two possible origins for g-value enhancements. Shock compression region and coronal ejecta Shock compression region and coronal ejecta Shell-shape events associated with halo CMEs Shell-shape events associated with halo CMEs Fast (slow) CMEs were decelerated (accelerated) during propagation. Fast (slow) CMEs were decelerated (accelerated) during propagation. Deceleration rates of fast CMEs correlated with speed difference to the ambient solar wind. Deceleration rates of fast CMEs correlated with speed difference to the ambient solar wind. Interaction with the ambient SW plays an important role in evolution of interplanetary CMEs. Interaction with the ambient SW plays an important role in evolution of interplanetary CMEs.

13 Future Subject: New IPS Antenna Aperture Size: A e ~ 3520×cosθ×η( ㎡ ) Efficiency η ~ 90% Meridian Transit Observations Antenna Beam: 1 (Steerable in NS-direction) 327 MHz SWFT (Solar Wind Imaging Facility of Toyokawa) To improve spatial resolution Increase No. of Radio Sources Large Aperture Antenna

14 Existing STEL IPS Antenna SWIFT (New IPS Antenna) Improved Resolution of IPS Mapping Observations


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