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) Time lag Good Points of IPS Observations Global coverage Long-term monitoring Interplanetary Scintillation; IPS

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

4. STEL IPS Antennas as Viewed in Google Earth Fuji IPS Telescope E-W 100m, N-S 20m Solar Wind Imaging Facility Telescope; SWIFT (Toyokawa) N-S 106m, E-W 41m Kiso IPS Telescope E-W 75m, N-S 27m 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 Spectrum Fitting Method (Single-station meas.) Speed V 1st. =459km/s Axial Ratio=1.07 Spectral Index=3.8 3C273 2012/9/3 Cross Correlation Method (3-station meas.) Speed V 3st. = 457±13 km/s from IPS obs. for 3C273 in 2012 V3st. (km/s) V1st. (km/s) Correlation ~0.47 V 1st /V 3st =1.04±0.24

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

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

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 All Lat. High Lat. >70° Low Lat. <10° Speed V Steady decrease (increase) in high (low) ΔNe area Marked growth of low ΔNe region at low latitudes Note that observation coverage is poor for 2010 SC23 SC24 Density fluctuations ΔNe(~Ne)

11. North-South Asymmetry of Solar Wind Speed Distribution over Poles (1985 ～ 2012) North Pole South Pole 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.

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.

14. 327-MHz Radio Sky Observed by SWIFT 408MHz Radio Sky (Haslam et al., 1982) Note: The system temperature increases at low elevation

15. 41m(E-W) 106m (N-S) Solar Wind Imaging Facility Telescope (SWIFT) Frontend and signal combiners Cylindrical parabolic reflector Dipole antennas 7.2m

16. 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

17. Specifications of STEL IPS Radiotelescopes Toyokawa (SWIFT) Fuji (FIT) Kiso (KIT) Sugadaira Tsys (K)146151221229 NF0.720.871.610.75 Pre-amplifierHEMTGa-As FETTransisterGa-As FET Ae ( ㎡ ) 1970 (@zenith) 150014091120 Beam Cont. N- S ElectronicalMechanical Beam Cont. E- W (Fixed)Electronical Physical Aperture 108 m NS × 40 m EW 20 m NS × 100 m EW 27 m NS × 75 m EW 20 m NS × 100 m EW

18. Comparison between New and Old IPS System Specifications NewOld A/D Resolution16 bits13 bits Sampling Period20 ms (median mean of 10kHz sampling data) 50 ms Start/End Time Resolution Every 0 secondsEvery 0 minutes Observation TimeJST (UT)Sidereal Time Duration of IPS Obs~2.7 min7.5 – 15 min 1 Block for FFT Analysis512 points1024 points Automatic Gain Cont. (H/W) NoneYes High-Pass Filtering for IPS Data (H/W) NoneYes PCWin-XP (samba/nfs)Win95/MS-DOS (nfs)

19. Strong Source Observations

20. IPS Power Spectra Noise level