Upgrade of STEL Multi-Station Interplanetary Scintillation System and Recent Observations of the Solar Wind

Munetoshi Tokumaru, Masayoshi Kojima, Ken’ichi Fujiki, Hiroaki Itoh, and Tomoya Iju

(STEL, Japan).

Given by Mario M. Bisi (CASS-UCSD)

and Periasamy Manoharan (Ooty)

STEL 327-MHz Multi-Station IPS System

SWIFT

Kiso IPS Telescope (KIT)

Fuji IPS Telescope (FIT)

Sugadaira antenna

Toyokawa antenna

Measurements•Solar wind speed •Scintillation level (g-value)~ΔNe

41m(E-W)

106m (N-S)

New IPS Antenna at ToyokawaSWIFT (Solar Wind Imaging FaciliTy)SWIFT (Solar Wind Imaging FaciliTy)

•Meridian Transit Obs.•Beam: 1 (Steerable in NS)•Frequency 327 MHz

Effective Area: Ae ～ 3382 ㎡ ×cosθ×η×D2(θ)η~90% 、 D(θ): directivity of dipole

Receiver Housing

Variations of Scintillation Level and g-value for Source B1730-13 in 2008

IPS level

IPS level

g-value

Time

Time

Radial Distance The g-value represents the relative variation of scintillation level; i.e. solar wind density fluctuations ΔNe (Gapper et al., 1982).

)(RS

Sg

bbRS

All-Sky g-maps2008/11/04

Toyokawa Kiso

Model Fitting Analysis of IPS Power Spectrum

Speed=379km/sAxial Ratio=0.99Spectral Index=3.17

Speed=499km/sAxial Ratio=0.51Spectral Index=4.34

3C48 2009/4/6 3C49 2009/4/6

Further Development of Multi-Station IPS System

Upgrade of Fuji and Kiso IPS Telescopes Dipoles, Antenna Driving System, Receiver Backend, PCs (FY2009-2010) Receiver Frontend (FY2011; not funded yet)

This allows us to take correlation between Toyokawa and Fuji, Kiso to derive the solar wind speed

Fuji IPS Telescope (FIT) Kiso IPS Telescope (KIT)

1991 2000

Solar wind speed maps

Blue= fastRed = slow

1996(Solar Minimum)

Comparison of Solar Wind Speed Maps between CR 1910 and 2070

2008.5.13~6.9

1996.6.1~6.28

Fast winds exist over the poles and equator.Slow winds are in between them. i.e. Non-Dipolar Structure.

The previous minimum data exhibit a Dipolar Structure.

Synoptic Carrington Solar Wind Speed Maps for 2008 (Cycle 23/24) and 1996　（ Cycle 22/23)

1. Equatorial fast wind

2. Rapid evolution of the large-scale structure

3. Larger latitude width of slow wind region

Summary

Upgrade Project of STEL Multi-Station IPS System Development of a New IPS Antenna at Toyokawa

(SWIFT), and Preliminary Observations Improvement of Fuji and Kiso IPS Antennas

Recent STEL Observations Peculiar Aspect of the Current Sunspot Minimum

Ref. Tokumaru et al., GRL, in press, 2009 (doi:10.1029/2009GL037461).

Continuous monitoring of the solar wind is needed.

Toyokawa IPS Workshop2007 October 30-31

A Series of IPS workshops San Diego, US (2004), Push

chino, Russina (2006) Topics

IPS Observations and Space Weather Studies

Collaboration with Spacecraft Mission

Basic Sciences Using Heliospheric Sounding Measurements

IPS World Network and Common Database

22 participants from US, UK, Germany, India, Russia, Mexico, and

Japan

STELMexicoIndia

UCSDUK/EISCAT

Russia

MWA

IPSWLFR