Decadal Variations of Solar Magnetic Field, Heliosphere
and the Cosmic Rays,
and their Impact on Climate Change
Hiroko MIYAHARA,
Institute for Cosmic Ray Research,
The University of Tokyo, Japan
hmiya@icrr.u-tokyo.ac.jp
Collaborators
Yusuke Yokoyama (ORI, The Univ. of Tokyo)
Yasuhiko T. Yamaguchi (ORI, The Univ. of Tokyo)
Takeshi Nakatsuka (Nagoya University)
Hong K. Peng (The Univ. of Tokyo)
Yukihiro Takahashi (Hokkaido University)
Mitsuteru Sato (Hokkaido University)
Hiroyuki Matsuzaki (MALT, The Univ. of Tokyo)
Solar modulation of Galactic Cosmic Rays (GCRs)
・Charged particles (mainly protons)
・Accelerated at supernova remnant
@ ~ edge of the heliosphere
Heliosphere
@Earth
B
GCR
Webber & Higbie 2010
・diffusion
・advection by solar wind
・drift
Solar wind
CME
Parker spiral
(Wavy current sheet)
Cosmic ray variation & Solar magnetic polarity
Gradient B drift
Ｓ
Ｎ
Ｓ
Ｎ
Ｎ
Ｓ
Ｎ
Ｓ
v =B×∇B
Positive
polarity
Earth
Heliosphere
4000
300
3500
Cosmic rays
200
Sunspot number
3000
100
2500
2000
0
1950
Negative
polarity
Gradient B drift
v =B×∇B
400
1960
1970 1980
Year AD
1990
2000
1. Magnetic polarity
Ｎ
Sun
Ｓ
or
Ｓ
Ｎ
Earth
2. Tilt angle
Solar cycle minimum
Heliosphere
Jokipii&Kota 2007
Solar cycle maximum
.
Sunspot Number
Sunspot
number
Sun
at Climax
Fluxrays
Neutron
Cosmic
4500
Variable “22-year” variation of cosmic rays
Modern: 5-75 degrees
Expected cosmic rays
Solar min
1. Solar polarity
Solar max
(degree)
2. Tilt angle
Kota&Jokipii, 2003
If 30-75 degrees
Solar min
If 0-75 degrees
Solar min
Solar max
Solar max
Miyahara et al.,2009
Reconstructed solar decadal cycles in the past
Maunder Minimum
250
200
150
100
50
0
1600
~11 yrs ~10 yrs
~10.5 yrs
~12 yrs
~13.5 yrs
14C
(permil)
30
Spoerer
10
1800 1900
Year AD
2000
Sunspot Number
（Usoskin, 2004）
Actual mean length
over the shaded
~9 yrs
period
1700
~11 yrs
~14 yrs
~13 yrs
(+/- 1yr)
Dacadal:
Stuiver et al., 1998
Maunder
Dalton
Wolf
(Decadal)
Oort
Annual:
Miyahara et al.,
2004, 2006,
2007, 2008
-10
-30
800
1100
1400
Year AD
1700
2000
Variable “22-year” variation of cosmic rays
Modern: 5-75 degrees
Expected cosmic rays
Solar min
1. Solar polarity
Solar max
(degree)
2. Tilt angle
Kota&Jokipii, 2003
If 30-75 degrees
Solar min
If 0-75 degrees
Solar min
Solar max
Solar max
Miyahara et al.,2009
Pattern of cosmic ray variation at the Maunder Minimum and present
(a)
Based on
Kota&Jokipii, 1983; 2003
GCRs
The Sun
Earth
(a) 0 deg. at cycle min
(b) 5 degs. at cycle min
(b)
GCRs
The Sun
Earth
“Flattened current sheet
model” reproduces
10Be variation
10Be flux
Heliospheric
Magnetic field
0.02
0.015
0.01
0.005
Berggren et al., 2009
1620
1640
1660
1680
Year AD
1700
1720
1740
1760
Cosmic-ray “22-year (28-year)” variation at the Maunder Minimum
Maunder Minimum
14C (inverted)
Solar cycle
Miyahara et al., 2004; 2008
－ ＋
－
－
＋
＋ － ＋
Filtered 14C
Cosmic rays
10Be
Ice core:
a few years of dating errors
Berggren et al.,
2009
GSN
10Be flux
Tree ring: No dating error
14-year cycle
0.02
0.015
0.01
0.005
1620
1640
1660
1680
1700
1720
1740
1760
Year AD
Features of cosmic-ray variation
・ Periodic cosmic ray enhancements, but only at the negative polarity
(~28-year periodicity)
・ 1-year scale enhancement, 30-50% higher than those for positive polarity
・ Significant manifestation of drift effect
Miyahara et al., IAU proc., 2009, Yamaguchi et al., PNAS, 2010
Climate response to cosmic-ray spikes during the Maunder Minimum
Temperature index
－ ＋
Warm
Cold
－
＋ － ＋ － ＋
Yamaguchii, Miyahara et al., PNAS, 2010
Vinther, 2003
Temperature in Greenland
（Vinther et al., 2003）
Maunder Minimum
Dry
Humid
RH anomaly
20
Our results
Humidity in Japan
10
around June
0
(Yamaguchi, Miyahara et al., 2010)
-10
Errors =0.2%
-20
High
10Be flux
Low
0.02
（Berggren et al.,
2009 ）
GCR flux
(Berggren et al., 2009)
0.015
0.01
0.005
1620
1640
1660
1680
Year AD
1700
1720
1740
1760
These spikes can be utilized to trace
GCR effect on climate system
Humidity anomaly
~4 sigma
GCR anomaly
No time lag!
Yamaguchi, Miyahara et al., PNAS, 2010
Possible influence of solar rotation on clouds?
Takahashi et al., ACP, 2010
Hong, Miyahara et al., JASTP, 2010
(OLR)
27-day signal in solar related parameters
Sunspot
Num ber
250
Frequency spectrum of cloud height variation
120-140 E, 0-20 N
54-days
200
54-days
150
27-days
100
F10.7 cm flux
(10-22 W /m 2・Hz)
50
0
1999
1999.4
250
1999.
1999.
26
1999.
1999.
48
1999.
2000
6
1999.8
1999.
1999.
26
1999.
1999.
48
1999.
2000
6
1999.8
1999.
1999.
26
1999.
1999.
48
1999.
2000
6
1999.8
200
150
100
1999
1999.4
6400
G C R flux
2000
6200
2000
－Solar
max
－Solar min
6000
5800
5600
1999
1999.4
Year AYear
D AD
2000
Year A D
Unsolved periods with 30-60 days in tropical clouds
(Madden-Julian Oscillation) may be under the influence
of solar rotation
Possible influence of solar rotation on clouds?
Hong, Miyahara et al., JASTP, 2010
F10.7
Solar rotational signals are
imprinted on to Madden-Julian Oscillation
(only at solar cycle maxima)
Cloud height
Influence of QBO on 27-day signal at solar max
Hong, Miyahara et al., JASTP, 2010
QBO East/ Solar Max
QBO East/ Solar Min
QBO West/ Solar Max
QBO East/ Solar Min
> QBO influence on tropospheric cloud activity
> Stronger Stratosphere-Troposphere interaction at solar max?
Summary
• Solar magnetic properties (polarity, structure, cycle lengths)
are also important in understanding climate pattern
• Madden-Julian Oscillation might be the key for
understanding solar influence
B
GCR
Solar wind
CME
Parker spiral