1

“Does the Sun Vary Enough?”

Leif Svalgaard

Stanford University, CA, USAleif@leif.org

http://www.leif.org/research

Eddy Symposium, Oct. 22, 2010

2

Was the Little Ice Age Global?

Sun that gives all things birth

Shine on everything on earth!

If that's too much to demand

Shine at least on this our land

If even that's too much for thee

Shine at any rate on me

Piet Hein (Danish Poet, 1905-1996)

3

Craig Loehle: Global Temperature Reconstruction [non-tree ring].

Range ~1ºC

Little Ice Age

Medieval Warm Period

4

Measurement of TSI by spacecraft

0.1%

Annual Variation (due to variation of solar distance) is 70 times larger than solar cycle variation:

Solar activity

Several cavities

5

TSI is the combined effect of sunspot dimming and facular brightening (2x)

Faculae are areas with significant magnetic fields near sunspotsdifference

6

Degradation of Active Cavity Instruments due to Harsh Space Environment

y = 1.00328899316e-0.00001268600x

1360

1361

1362

1363

1364

1365

1366

1367

0 1 2 3 4 5 6 7

1.003050

1.003100

1.003150

1.003200

1.003250

1.003300

1.003350

1.003400

1.003450

1.003500

2004.0

PMOD

SORCE

Ratio

Comparison PMOD and SORCE-TIM

2005.0 2006.0 2010.02009.02008.02007.0 2011.0

SOHO Keyholes

In an ideal world the ratio [or difference] between PMOD TSI (SOHO at L1) and SORCE TIM TSI (LEO) should be constant. This is not the case. The ratio PMOD/SORCE is slowly decreasing exponentially:

Sometime in 2003 the azimuth drive of the high gain antenna (on SOHO) got stuck. The operations people were able to move to a position which was ok for most of the halo orbit (±30 degrees seen from Earth). As the antenna is locked at one azimuthal angle, SOHO is turned around its solar axis by 180 deg for the East or West legs of the orbit, respectively. So in this context, the ’keyhole’ is when low emission in the antenna pattern close to extremes of the halo orbit are encountered. The different orientation of the spacecraft may have thermal effects.

7

Reconstructions of TSI often use the Sunspot Number [going back 400 years]

Different series of sunspot numbers are in use, according to what fits your pet theory the best

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Early Reconstructions TSI ~ TSI0 +a·SSN + b·<SSN>11yr

Now

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Solar Magnetic Field Heliospheric Magnetic Field Geomagnetic Activity:Centennial Secular Increase ?

Lockwood et al., 1999 Aa-index and Method Wrong

10

HMF from Geomagnetism

y = 1.4771x0.6444

R2 = 0.8898

y = 0.4077x + 2.3957

R2 = 0.8637

0

2

4

6

8

10

0 2 4 6 8 10 12 14 16

IDV

HMF B as a Function of IDV09

B nT 1963-2010

0

2

4

6

8

10

1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

B nT

Year

B (IDV)

B (obs)

Heliospheric Magnetic Field Strength B (at Earth) Inferred from IDV and Observed

13 23

NowThen

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Historical Sunspot Number Records Probably Not Correct

0

10

20

30

40

50

60

70

1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

HLS Helsinki Nine Station Chain NUR Nurmijarvi

Stability of Amplitude of Diurnal Variation of East Component

nT

Year

Current System in Ionosphere Created by UV Radiation Produces Diurnal Magnetic Effect at the Surface (1722)

Morning

Afternoon

12

So, Reconstructions of TSI are converging towards having no ‘background’

13

Global Temp.

Solar Output, TSI

10Be and 14C-based reconstructions are largely in agreement

TSI, Steinhilber et al.

14C10Be

LIA

MWP

+1 W/m2 +0.05ºC

-1 W/m2 - 0.05ºC10Be

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Why Were There No Sunspots During the Maunder Minimum?

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Magnetic Field is decreasing. Intensity is increasing => less contrast

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The F10.7 cm Microwave Flux Also Shows that Lately Sunspots are Harder to See

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

?

Ratio of Observed Sunspot Number to Simulated SSN

Zurich SIDC

+12% correction

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