Transcript Vistas in Solar Activity Leif Svalgaard Stanford University Brown Bag Lunch, Tucson, Jan.

Vistas in Solar Activity
Leif Svalgaard
Stanford University
Brown Bag Lunch, Tucson, Jan. 2013
1
Indicators of Solar Activity
• Sunspot Number (and Area,
Magnetic Flux)
• Solar Radiation (TSI, UV, …,
F10.7)
• Cosmic Ray Modulation
• Solar Wind
• Geomagnetic Variations
• Aurorae
• Ionospheric Parameters
• Oscillations
• Climate?
• More…
Longest direct
observations
Penumbra
Umbra
After Eddy, 1976
Solar Activity is Magnetic Activity
2
The Sunspot Number(s)
• Wolf Number = KW (10*G + S)
• G = number of groups
• S = number of spots
• Group Number = 12 KG G
Douglas Hoyt and Kenneth
Schatten devised the Group
Sunspot Number using just
the group count (1993).
Unfortunately a K-factor
was also necessary here,
so the result really depends
on how well the K-factor
can be determined
Rudolf Wolf (1816-1893)
Observed 1849-1893
Ken Schatten
3
Waldmeier’s Description of the Weighting
of Sunspots that began in the 1940s
Zürich
Locarno
1968
“A spot like a fine point is counted as one spot; a larger spot, but still without
penumbra, gets the statistical weight 2, a smallish spot with penumbra gets 3,
and a larger one gets 5.” Presumably there would be spots with weight 4, too.
This very important piece of metadata was strongly downplayed and is not generally known
4
Locarno, a week later
No Weight
2
4
4
6
2
4
2
2
1
2
1
SDO AIA 450nm
SDO HMI LOS
Combined Effect
of Weighting and
More Groups is
an Inflation of the
Relative Sunspot
Number by 20+%
I have re-counted
43,000 spots without
weighting for the last
ten years of Locarno
observations.
30
Groups
‘Spots’
10*11+52=162; 10*11+30=140;
162/140=1.16
5
Double-Blind Test of My Re-Count
I proposed to the Locarno
observers that they should
also supply a raw count
without weighting
Marco Cagnotti
For typical number of spots
the weighting increases the
‘count’ of the spots by 3050% (44% on average)
6
Comparison Zurich Sunspot Number and That Derived from Sunspot Areas
300
1000
Monthly Means
Rz
Rz
Rz
250
100
Rc = 0.3244*SA0.732
10
200
1
0.1
1
10
100
1000
10000
SA
SA
0.1
150
100
50
0
1875
1880
1885
1890
1895
1900
1905
1910
1915
1920
1925
1930
1935
1940
1945
Comparison Zurich Sunspot Number and That Derived from Sunspot Areas
300
0.732
RZ /SA
>1000 uH
Monthly Means
0.7
Rz
250
(projected)
0.8
Monthly Means
0.6
0.5
0.732
Rc = 0.3244*SA
0.4
0.3
0.2
200
0.1
Wolfer
Brunner
Waldmeier
SIDC
0
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
150
100
50
0
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
The 20% Inflation Caused by Weighting Spot Counts
2000
7
Correcting for the 20% Inflation
Sunspot Number (Official SIDC View)
200
180
Rcorr = Rofficial * 1.2 before ~1947
160
140
120
100
80
60
40
20
0
1700
1725
1750
1775
1800
1825
1850
1875
1900
1925
1950
1975
2000
This issue is so important that the
official agencies responsible for
producing sunspot number series
have instituted a series of now
ongoing Workshops to, if at all
possible, converge to an agreed
upon, common, corrected series:
http://ssnworkshop.wikia.com/wiki/Home
The inflation due to weighting is now
an established and accepted fact
Modern Grand Max?
GSN
That the corrected sunspot number is so
very different from the Group Sunspot
Number is a problem for assessing past
solar activity and for predicting future
activity. This problem must be resolved.
8
The Ratio between the Group Sunspot
Number and the [corrected] Sunspot number
Shows that the significant discrepancy is largely due to data from the 1880s
9
Building Backbones
Building a long time series from observations made over
time by several observers can be done in two ways:
• Daisy-chaining: successively joining
observers to the ‘end’ of the series,
based on overlap with the series as it
extends so far [accumulates errors]
• Back-boning: find a primary observer
for a certain [long] interval and
normalize all other observers
individually to the primary based on
overlap with only the primary [no
accumulation of errors]
When several backbones have been constructed we can
join [daisy-chain] the backbones. Each backbone can be
improved individually without impacting other backbones
Chinese Whispers
Carbon Backbone 10
The Wolfer Backbone
Alfred Wolfer observed 1876-1928 with the ‘standard’ 80 mm telescope
1928
1876
Rudolf Wolf from 1860 on
mainly used smaller 37
mm telescope(s) so those
observations are used for
the Wolfer Backbone
80 mm X64
37 mm X20
11
Normalization Procedure
Number of Groups
Number of Groups: Wolfer vs. Wolf
12
9
Wolfer
8
Yearly Means 1876-1893
10
Wolf*1.653
7
8
Wolfer = 1.653±0.047 Wolf
6
2
R = 0.9868
5
Wolfer
6
4
4
3
Wolf
2
2
1
Wolf
0
1860
F = 1202
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
1865
1870
1875
1880
1885
1890
1895
Number of Groups
Number of Groups: Wolfer vs. Winkler
9
9
Wolfer
8
Yearly Means 1882-1910
8
Winkler*1.311
7
7
Wolfer = 1.311±0.035 Winkler
6
5
5
4
4
3
3
2
2
1
0
1
2
3
4
5
6
Winkler
1
Winkler
0
Wolfer
6
2
R = 0.9753
7
0
1880
1885
1890
1895
1900
1905
1910
12
The Schwabe Backbone
Schwabe received a 50 mm telescope from Fraunhofer in 1826 Jan 22. This
telescope was used for the vast majority of full-disk drawings made 1826–1867.
For this backbone
we use Wolf’s
observations with
the large 80mm
standard telescope
?
Schwabe’s House
13
The Wolfer & Schwabe Backbones
Wolfer Group Backbone
14
14
Wolfer Backbone Groups
12
Number of Observers
12
Standard Deviation
10
10
8
8
6
6
4
4
2
2
0
1840
0
1850
1860
1870
1880
1890
1900
1910
1920
1930
1940
Schwabe Group Backbone
8
7
10
Number of Observers
Schwabe Backbone Groups
9
8
6
Standard Deviation
7
5
6
4
5
4
3
3
2
2
1
0
1790
1
1795
1800
1805
1810
1815
1820
1825
1830
1835
1840
1845
1850
1855
1860
1865
1870
1875
1880
0
1885
14
Joining two Backbones
Comparing Schwabe with Wolfer backbones over 1860-1883 we find a normalizing factor of 1.55
Comparing Overlapping Backbones
Reducing Schwabe Backbone to Wolfer Backbone
12
12
10
10
1860-1883
Wolfer
1.55
8
6
6
4
4
2
0
1860
Wolfer = 1.55±0.05 Schwabe
8
Schwabe
R2 = 0.9771
2
Wolfer
Schwabe
0
1865
1870
1875
1880
1885
1890
1895
1900
0
1
2
3
4
5
The Group Sunspot Number is now defined as 12 * Number of Groups
6
7
15
8
The corrected Sunspot Number Series [no Modern Grand Maximum]
16
Wolf’s Discovery: rD = a + b RW
.
North X
rY
Morning
H
rD
Evening
D
East Y
Y = H sin(D)
dY = H cos(D) dD
For small D, dD and dH
A current system in the ionosphere [E-layer] is
created and maintained by solar FUV radiation.
Its magnetic effect is measured on the ground.
(George Graham, 1722)
17
The Diurnal Variation of the Declination for
Low, Medium, and High Solar Activity
8
6
9
10
Diurnal Variation of Declination at Praha (Pruhonice)
dD'
4
1957-1959
1964-1965
2
0
-2
-4
-6
-8
-10
Jan
Feb
Mar
Apr
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
Diurnal Variation of Declination at Praha
8
6
May
dD'
1840-1849
rD
4
2
0
-2
-4
-6
-8
-10
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Year
18
Wolf’s Original Geomagnetic Data
Wolf and Wolfer's Diurnal Ranges of Declination for their Long-running Stations
14
Wolf found a
very strong
correlation
between his
Wolf number
and the daily
range of the
Declination.
dD'
12
10
8
6
4
Praha (Prague) - Christiania (Oslo) - Milano (Milan) - Wien (Vienna)
2
0
1835
1840
1845
1850
1855
1860
1865
1870
1875
1880
1885
1890
1895
1900
1905
1910
1915
1920
1925
Diurnal Range Compared to Scaled International Sunspot Number
70
RI*
60
rY (nT)
50
40
30
20
10
Today we know that the relevant parameter is the East Component, Y, rather
than the Declination, D. Converting D to Y restores the stable correlation,
especially around the critical time near 1885 where the GSN begins to deviate
0
1835
1840
1845
1850
1855
1860
1865
1870
1875
1880
1885
1890
1895
1900
1905
1910
1915
1920
Wolfer found
the original
correlation was
not stable, but
was drifting
with time and
gave up on it in
1923.
1925
The geomagnetic response is just what we would expect from the Sunspot Number
19
Using rY from nine
station ‘chains’ we
find that the
300
F10.7
250
y = 5.4187x - 129.93
R2 = 0.9815
200
correlation
150
Canonical Relationship SSN and F10.7
250
1952-1990
F10.7
200
100
y = 0.043085x 2.060402
R2 = 0.975948
150
100
50
y = -0.0000114x 3 + 0.0038145x 2 + 0.5439367x + 63.6304010
R2 = 0.9931340
50
SSN
rY
0
0
20
40
60
80
100
120
140
160
180
200
0
30
35
40
45
50
55
60
nT 70
65
between F10.7 and
rY is extremely
good (more than
98% of the
variation is
accounted for)
Solar Activity From Diurnal Variation of Geomagnetic East Component
250
200
Nine Station Chains
F10.7 sfu
F10.7 calc = 5.42 rY - 130
150
100
12
13
14
15
16
17
18
19
20
21
22
23
1980
1990
2000
50
25+Residuals
0
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
2010
2020
So, the geomagnetic diurnal variation is a good proxy for the F10.7 microwave flux
20
24-hour running means of the Horizontal Component of the low- & midlatitude geomagnetic field remove most of local time effects and leaves a
Global imprint of the Ring Current [Van Allen Belts]:
A quantitative measure of the effect can be formed as a series of the unsigned
differences between consecutive days: The InterDiurnal Variability, IDV-index.
21
Similar to Bartels’ u-index and the ‘Nachstörung’ popular a century ago.
IDV is strongly correlated with solar wind
magnetic field B, but is blind to solar wind speed V
nT
10
10
So, from IDV we can
get HMF B
B obs
8
8
B calc from IDV
6
6
B obs median
4
4
B std.dev
2
2
100% =>
18
Coverage
0
0
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
16
IDV vs. Solar Wind Speed V (1963-2010)
IDV
14
HMF B as a Function of IDV09
10
B nT
12
1963-2010
10
8
8
6
6
4
2
4
y = 1.4771x0.6444
2
R = 0.8898
y = 0.4077x + 2.3957
2
R = 0.8637
4
10
0
0
2
6
8
12
14
2
R = 0.0918
2
V km/s
IDV
16
0
350
400
450
500
550
22
The IHV Index gives us BV2
Calculating the variation
(sum of unsigned differences
from one hour to the next) of
the field during the night
hours [red boxes] from
simple hourly means (the
Interhourly Variation) gives
us a quantity that correlates
with BV2 in the solar wind
23
Physical meaning of IHV: the index is directly proportional to
the auroral power input, HP, to the polar regions
POES
24
Polar Cap Diurnal Variation gives us V times B
E=-VxB
This variation has
been known for more
than 125 years
25
Overdetermined
System: 3 Eqs,
2 Unknowns
B
= p (IDV)
BV2 = q (IHV)
Gjøa
VB = r (PCap)
Here is B back to the 1830s:
Heliospheric Magnetic Field at Earth
10
9
B
8
7
6
5
4
3
HMF from IDV-index
2
HMF observed in Space
1
0
1830
1840
1860
1870
1880
1890
1900
1910
1920
1930
1940
Cosmic Ray Modulation Parameter
1400
ϕ
1200
1850
1950
1960
1970
1980
1990
2000
2010
26
Solar Activity 1835-2012
Sunspot Number
Monthly Average Ap Index
60
Ap Geomagnetic Index (mainly solar wind speed)
50
40
30
20
10
B nT
0
1840
Heliospheric Magnetic Field Strength B (at Earth) Inferred from IDV and Observed
1850
1860
1870
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
10
B (IDV)
8
6
13
23
4
0
1830
B (obs)
Heliospheric Magnetic Field at Earth
2
1840
1850
1860
1870
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
Activity now is similar to what it was a century ago
1990
2000
2010
Year
27
The Cosmic Ray Record is also a Proxy for
Solar Activity, but there are Problems
17 pounds/yr
2 oz/year
Steinhilber et al. 2012
28
Cosmic Ray Modulation as Governed by
Strength of Magnetic Field in Heliosphere
Heliospheric Magnetic Field at Earth
10
B
9
8
7
6
5
4
3
HMF Observed in Space
HMF deduced from Geomagnetic Record
2
1
0
1830
1840
1850
1860
1870
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Cosmic Ray Modulation Parameter
1400
ϕ
Problem
1200
Observed Modulation
1000
800
600
400
200
0
1830
HMF scaled to Neutron Monitor Modulation
1840
1850
1860
1870
1880
1890
1900
1910
1920
1930
Ion
1940
Neutron
1950
1960
1970
1980
1990
2000
201029
31
Total Solar Irradiance at 1 AU
M.M.
GSN
Cosmic Ray Proxy [Berggren et al.]
30
NGRIP is better than Dye-3
NGRIP
Unreliable
Dye-3
Note scale difference by factor of 5. Dye-3 has problems between 1680-1770.
The Figures show the Flux of the 10Be atoms, not the Concentration.
31
‘Burning Prairie’ => Magnetism
Foukal & Eddy, Solar Phys. 2007, 245, 247-249
32
Removing the discrepancy between the Group
Number and the Wolf Number removes the
‘background’ rise in reconstructed TSI
I expect a strong reaction against ‘fixing’ the GSN from people that ‘explain’
climate change as a secular rise of TSI and other related solar variables
33
Kopp/LASP
Some More TSI
Reconstructions
Crucial question: is there a slowly
varying background? I think not.
34
Who Cares?
The Public cares!
35
Predictions of SC24
Prediction of Solar Cycles
North - South Solar Polar fields [microTesla]
We are here now
State of the Art
From NOAA-NASA Panel
400
WSO
MSO*
300
200
100
0
1965
-100
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
-200
Polar Field Reversal
at Solar Maximum
-300
-400
Solar Dipole Divided by Sunspot Number for Following Maximum
4.0
3.5
3.0
Polar Field Precursor Method
WSO
R24
2.5
45
2.0
1.5
20
21
22
23
24
72
1.0
Min
0.5
0.0
1965
1970
1975
1980
1985
1990
1995
165
2000
2005
2010
2015
36
Polar Concentrations in 17 GHz
Radioflux from Nobeyama
Rotate and long-lived
North - South Solar Polar fields [microTesla]
400
WSO
MSO*
300
200
100
0
1965
-100
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
-200
-300
-400
37
Evolution of Patches over the Cycle
W
S
Reversal
E
N
Reversal
W
38
Polar Magnetic Landscape
Tsuneta et al. ApJ, 2008
39
How is Cycle 24 Evolving? As Predicted!
So, the polar field precursor method seems to work
Active Region Count
Numbered Active Regions per Month
D. Hathaway
Prediction
21
1980
22
1985
1990
23
1995
2000
24
2005
2010
2015
2020
Cycle 24 is beginning to look like Cycle 14
14
24
Lowest in a 100 years
40
Observed Sunspot Number Divided by Synthetic SSN (1952-1990)
1.4
600
SIDC
1.2
R>10
500
0.655 SWPC
1.0
400
0.8
250
SSN
1952-1990
200
y = 0.000017x3 - 0.008270x2 + 2.367415x - 119.487222
R2 = 0.993433
150
0.6
?
100
1996-2012
300
R
Something is
happening
with the Sun
50
200
F10.7
0
0.4
0
50
100
150
200
250
Observed Sunspot Number Divided by Synthetic SSN (1952-1990)
1.4
Spots per Group for Locarno
600
SIDC
1.2
0.2
0.0
R>10
R
14
500
0.655 SWPC
1.0
100
400
0.8
0.6
19
?
0.2
R
20
100
21
22
1975 1980
1985 1990
23
S/G
21
22
23
10
24
24
0
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
0.0
1950 1955
19
1960 1965
20
1970
12
300
R
200
0.4
(b)
8
0
1995
2000 2005
2010 2015
?
6
4
Spots per Group declining
SSN obs / SSN*
3.0
1975
1980
1985
1990
1995
2000
2005
2010
2
0
2015
SSN* = 54.7 MPSI 1.0089
2.5
2.0
5-month
running average
Magnetic Plage
Strength Index
Umbral Magnetic Field
4000
3500
Livingston & Penn
B
Gauss
3000
1.5
2500
1.0
2000
0.5
?
Year
0.0
1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015
?
1500
1000
1998
No visible spots form
2000
2002
2004
2006
2008
2010
2012 Year
We don’t know what causes this, but sunspots are becoming more difficult to see or not forming as they
used to. There is speculation that this may be what a Maunder-type minimum looks like: magnetic fields
still present [cosmic rays still modulated], but just not forming spots. If so, exciting times are ahead. 41
Normalized to
same maximum
Evolution of
Distribution
of Magnetic
Field
Strengths
Distribution of Sunspot Magnetic Field Strengths
2005-2008
2009-2011
1998-2004
Normalized
to same area
1000
1250
1500
1750
2000
2250
2500
2750
3000
3250
3500
3750
Gauss
Sunspots form by assembly
of smaller patches of
magnetic flux. As more and
more magnetic patches fall
below 1500 G because of the
shift of the distribution, fewer
and fewer visible spots will
form, as observed
42
Small Spots are Disappearing
Percentage Frequency of Small Groups
60
50
60
A+B
When Yearly Number of Groups > 100
A+B
50
40
40
A
A
30
30
20
B
Spots per Group
B
20
10
Percentage Frequency
10
G
S/G
0
1950
G
0
1950
1960
1970
1980
1990
2000
2010
2020
1970
1990
2010
Zurich and Locarno
The occurrence of groups of class A and B is decreasing
as is the number of spots per group
43
Working Hypothesis
• The Maunder Minimum was not a serious
deficit of magnetic flux, but
• A lessening of the efficiency of the process
that compacts magnetic fields into visible
spots
• This may now be happening again
• If so, there is new solar physics to be
learned
44