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M. Tokumaru , K. Fujiki, and T. Iju (STEL, Nagoya University)

Interplanetary Scintillation Observations of the Solar Wind Using SWIFT and Upgraded STEL Multi-station System. M. Tokumaru , K. Fujiki, and T. Iju (STEL, Nagoya University). Interplanetary Scintillation Measurements of the Solar Wind.

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M. Tokumaru , K. Fujiki, and T. Iju (STEL, Nagoya University)

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  1. Interplanetary Scintillation Observations of the Solar Wind Using SWIFT and Upgraded STEL Multi-station System M. Tokumaru, K. Fujiki, and T. Iju (STEL, Nagoya University)

  2. Interplanetary Scintillation Measurements of the Solar Wind • Time Delay between IPS patterns at separated antennas → Solar wind speed V • Strength of IPS → Density Fluctuations ΔNe (~Ne) Interplanetary Scintillation; IPS • Good Points of IPS Observations • Global coverage • Long-term monitoring Time lag

  3. STEL Radiotelescope Array dedicated for IPS Observations Sugadaira Kiso • Data • Solar Wind Speed • Scintillation level (g-value) Aperture Size = ~ 2000or ~ 3400㎡ Frequency 327MHz Toyokawa Fuji

  4. STEL IPS Antennas as Viewed in Google Earth Kiso IPS Telescope E-W 75m, N-S 27m Solar Wind Imaging Facility Telescope; SWIFT (Toyokawa) N-S 106m, E-W 41m Fuji IPS Telescope E-W 100m, N-S 20m A new system for observation control and data acquisition has been developed in 2010 to collect IPS data simultaneously at three stations. This system enables to determine the solar wind speed from the cross correlation analysis. SWIFT-type low-noise amplifiers will be installed for Fuji and Kiso stations in this winter to improve sensitivity. Development of SWIFT in 2006-2008. Highest Sensitivity among the array

  5. Cross Correlation Analysis with Upgraded STEL IPS System Solid lines: Cross Correlation Dashed/Dotted lines: Auto Correlation Taking account of the baseline geometry, we determine the solar wind speed. For this case, we obtain V=522+/-3 km/s. Here, we assume the radial flow and the anisotropy.

  6. Comparison between Spectrum Fitting and Cross Correlation Methods from IPS obs. for 3C273 in 2012 3C273 2012/9/3 Correlation ~0.47 V1st/V3st=1.04±0.24 V1st. (km/s) V3st. (km/s) Cross Correlation Method (3-station meas.) Speed V3st.= 457±13 km/s Spectrum Fitting Method (Single-station meas.) Speed V1st.=459km/s Axial Ratio=1.07 Spectral Index=3.8

  7. 1996(Cycle 22/23 Minimum) 2000 1991 (Cycle 23 Maximum) (Cyclel 22 Maximum) Blue=Fast wind Red=Slow wind

  8. Year-by-Year Variations in Source Surface Area of Fast, Slow and Intermediate Speed Winds during 1985-2012 from STEL IPS observations Deficit of Slow Wind All Lat. High Lat. >70° Excess of Fast Wind Particularly at Low Lat. Low Lat. <10° Peculiar dynamo activity is going on. SC24 SC22 SC23

  9. Solar Maximum of Cycle 24:the smallest in last 100 years SC24 max

  10. Year-by-Year Variations of V (left) and ΔNe (right) Distribution on the Source Surface during 1997-2012 Density fluctuations ΔNe(~Ne) Speed V Steady decrease (increase) in high (low) ΔNe area All Lat. Note that observation coverage is poor for 2010 High Lat. >70° Marked growth of low ΔNe region at low latitudes Low Lat. <10° SC24 SC23 SC23 SC24

  11. North-South Asymmetry of Solar Wind Speed Distribution over Poles(1985～2012) N-S Difference Blue = Fast wind, Red = Slow wind Large N-S asymmetry in fast wind (blue) is observed in the declining phase of SC23 and SC24. North Pole South Pole

  12. Summary • Global observations of the solar wind have been carried out for more than 3 solar cycles using the multi-station IPS system of STEL. • Some interesting aspects of the solar wind in the cycle 24 are revealed from STEL IPS observations. These are considered as manifestation of peculiar solar dynamo activity in this cycle, and also suggest that a drastic change of global heliosphere is in progress. • We need to elucidate evolution of the solar wind during cycle 24 and beyond in detail.

  13. 327-MHz Radio Sky Observed by SWIFT Note: The system temperature increases at low elevation 408MHz Radio Sky (Haslam et al., 1982)

  14. Solar Wind Imaging Facility Telescope (SWIFT) 41m(E-W) Cylindrical parabolic reflector Dipole antennas 106m (N-S) Frontend and signal combiners 7.2m

  15. Upgrade of Fuji and Kiso IPS Systems • A new system for observation control and data acquisition has been developed for the STEL IPS array. • The new systems enable to collect IPS data simultaneously with the SWIFT and enable to determine the solar wind speed from the cross correlation analysis of 3-station data. • New low-noise amplifiers will be installed for these stations in this winter. Fuji IPS Telescope (FIT) E-W 100m, N-S 20m Kiso IPS Telescope (KIT) E-W 75m, N-S 27m

  16. Specifications of STEL IPS Radiotelescopes

  17. Comparison between New and Old IPS System Specifications

  18. Strong Source Observations

  19. IPS Power Spectra Noise level

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