Global Properties of Global Properties of Heliospheric Heliospheric Disturbances Disturbances Observed by Observed by

Interplanetary Interplanetary ScintillationScintillationM. TokumaruM. Tokumaru, M. Kojima, K. , M. Kojima, K. Fujiki, and M. YamashitaFujiki, and M. Yamashita

(Solar-Terrestrial Environment (Solar-Terrestrial Environment Laboratory, Nagoya University) Laboratory, Nagoya University)

Interplanetary Scintillation (IPS) Measurements as Interplanetary Scintillation (IPS) Measurements as a Tool for Studying Global Properties of CME in the a Tool for Studying Global Properties of CME in the

Solar Wind 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)

STEL 327-MHz Four-Station IPS STEL 327-MHz Four-Station IPS SystemSystem

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)

SOHO/LASCO Projection map of g-values between2000/7/11:22h 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 ΔＳ ; 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.

IPS Observations of an Earth-Directed CMEIPS Observations of an Earth-Directed CME(the 2000 Jun 6 halo CME event)(the 2000 Jun 6 halo CME event)

Observed g-value mapLASCO CME ImageEarth-directed CME

Retrieval of 3D Structure of Interplanetary CME by Retrieval of 3D Structure of Interplanetary CME by Model Fitting AnalysisModel Fitting Analysis

2 1 2( ) ( )cal eg K N w z dz

Earth

Sun

2 2

1

| | / minN

obs cal cali

g g g

ΔNe ModelObserved 　 g-map

Line-of-Sight

ΔNe: Density fluctuationsK: Normalizing factorw(z): IPS weightening functionz: Distance along los

q: Spectral indexΨ: Apparent source sizeλRF: Observing wavelength

Search for the best-fit parameters

dkzkzkkzw RFq

2exp

4sin)(

222

0

221

Sun

Earth

(Cf. Tappin, 1987)

ΔNe model ΔNe model – Enhancement Component -– Enhancement Component -

lapseSpeak TVR )2/(cos0

Ecliptic Plane

Enhanced ΔNe region (ICME)

EarthSun

Radial Distance

ΔNee-folding thickness D

θ : Separation AngleTlapse: Lapse Time after Lift-OffVS0 : Ave. Transit Speed

C0( 1)≒

C1

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.

Global Feature of CMEs in the Global Feature of CMEs in the Solar WindSolar Wind

1999 Sep 20 event 2000 Jul 10 event 2000 Jun 2 event

1999 Aug 17 event 2000 Jul 14 event1999 Apr 13 event2001 Aug 25 event

3D Reconstruction from IPS and 3D Reconstruction from IPS and White-light Observations for 2003 White-light Observations for 2003

October 28 CME EventOctober 28 CME Event

Propagation Speed Estimated from IPS: 1,083 km/s @0.42 AU Cf. Shock Transit Speed: 2,186 km/s @1AU

STEL IPS Solar Mass Ejection Imager (SMEI)SMEI-IPS Correlation(by B.V. Jackson)

Correlation Coefficient

Radial Variation of CME Radial Variation of CME SpeedsSpeeds

Coronagraph IPS

In Situ

(M. Yamashita, D. thesis)

Propagation speeds of ICME were derived by fitting a shell-shape model to IPS data.

Deceleration of Fast Deceleration of Fast CMEsCMEs

We fit a power law functioWe fit a power law function n RRaa to the deceleration pr to the deceleration profile of CME speeds in thofile of CME speeds in the solar wind frame.e solar wind frame.

The slope of radial fall deThe slope of radial fall depends on pends on difference betwdifference between initial CME speed and een initial CME speed and ambient flow speedambient flow speed..

Interaction between CME Interaction between CME and the ambient SW plays and the ambient SW plays an important rolean important role Cf. Drag force model (VrsnaCf. Drag force model (Vrsna

k & Gopalswamy, 2002).k & Gopalswamy, 2002).

aSWCME RVV

M. Yamashita, D. thesis

Pow

er-l

aw

Inde

x

a

Summary Summary STEL IPS observations were used to study global feSTEL IPS observations were used to study global fe

ature and propagation dynamics of CMEs in the solaature and propagation dynamics of CMEs in the solar wind.r wind.

Our results suggest thatOur results suggest that Some CMEs observed in the solar wind exhibited loop-shaSome CMEs observed in the solar wind exhibited loop-sha

pe distribution, and some had shell-shape distribution.pe 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 CMEsShell-shape events associated with halo CMEs Fast (slow) CMEs were decelerated (accelerated) during propagatiFast (slow) CMEs were decelerated (accelerated) during propagati

on.on. Deceleration rates of fast CMEs correlated with speed difference Deceleration rates of fast CMEs correlated with speed difference

to the ambient solar wind. to the ambient solar wind. Interaction with the ambient SW plays an important role in evolutiInteraction with the ambient SW plays an important role in evoluti

on of interplanetary CMEs.on of interplanetary CMEs.

Future Subject: New IPS AntennaFuture Subject: New IPS Antenna

Aperture Size: Ae ～ 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)SWFT (Solar Wind Imaging Facility of Toyokawa)

To improve spatial resolution

Increase No. of Radio Sources

Large Aperture Antenna

Existing STEL IPS Antenna

SWIFT　 (New IPS Antenna)

Improved Resolution of IPS Mapping Observations