1. Examine solar cycle variations (11/22 yrs.) of DA in SO & SI times.
32nd ICRC (August 15, 2011, Beijing) SH3.3 ID368
Solar cycle dependence of the diurnal anisotropy of 0.6 TeV cosmic ray intensity observed with the Matsushiro underground muon detector
K. Munakata1, C. Kato1, S. Yasue1, S. Mori1, M. Takita2, and J. Kota3
1Shinshu Univ., 2ICRR, 3Univ. of Arizona
Introduction.
Observation with Matsushiro (E-W) over 24 years in TeV.
Examine solar cycle variations (11/22 yrs.) of DA in SO & SI times.
Discussions.
(Munakata et al., ApJ, 712, 1100, 2010)

2. (Planetary and Space Sci., 13, 1965)
W. I. Axford
(Planetary and Space Sci., 13, 1965) SI
(Extragalactic) SO SI
(Galactic)

3. Diurnal anisotropy & harmonic dial
Obs.
Obs. - CG
Active period
Quiet period
00:00
06:00
12:00
18:00
1st harmonic dial
phase
amplitude
Compton-Getting

4. Solar cycle dependence of (by Matsushiro UG- detector in 1985-2008)
0.6 TeV GCR anisotropy
(by Matsushiro UG- detector in )
● SI: sidereal
■ SO: solar
△ ASI: anti-sidereal SI
(366 c/y)
Tibet AS ( )
0 h
18 h
6 h
ASI
(364 c/y)
CG effect
（solar min.） SO
(365 c/y)

5. (400 km/s solar wind travels ~180 AU)
activity
~15:00 LT SO
(CG subtracted)
max＝＋0.74
tCR=+26 months
(400 km/s solar wind travels ~180 AU) SI

6. SO SI max＝＋0.57 tCR=+14 months Solar activity ~03:00 LT
(CG subtracted) SI
~03:00 LT

7. The observed SI daily variation
Similar to the SI daily variation of multi-TeV GCR
except ~1/3 attenuation of amplitude

8. SI Steady increase of amplitude?
No correlation with the solar activity seen by Matsushiro
(3) SI
(Abdo et al., 2009)

9. Small solar cycle variation (if any)
only ~1/6 amplitude changing with the solar cycle
~1/3 attenuation by the solar modulation

10. MHD model heliosphere (Washimi & Tanaka)By z x P N P N
100
200
300 AU
Positive
Negative

11. Summary Additional SO anisotropy (+ CG anisotropy).
Amplitude shows a positive correlation with
the solar activity (max＝＋0.74)
Significant time lag (tCR =+26 months)
The average SI TeV is ~1/3 of the amplitude in multi-TeV region.
Steady increase of SI amplitude by Milagro is NOT caused by the decreasing solar activity.
Only ~1/4 of the SI attenuation varies in a weak correlation with the solar activity cycle.