Using the paleo-cosmic ray record to compare the solar activity during the sunspot minimum of 2006-2009 with those during the Spoerer, Maunder, and

Dalton Grand Minima

Ken McCracken

IPST, University of Maryland.

jellore@hinet.net.au

NESSC, Boston, 17April, 2014

U. New Hampshire, 14 April, 2014

McCracken and Beer, 2014

GALACTIC COSMIC RADIATION

SPALLATION OF ATMOSPHERICA, N and O.

TIME

1OBe

ICECORE

THE PALEO- COSMIC RADIATION RECORD

TREE RINGS

14C

DIFFERENT ATMOSPHERIC ANDSEQUESTRATION PROCESSES

5730 y 1.5x106 y

36Cl

> 120 investigator years of data

COSMOGENIC NUCLIDE PRODUCTION DURING THE PAST 10,000 YEARS

TWO INDEPENDENT MEASUREMENTS OF THE PAST

Beer et al, ICRC 2007

Steinhilber et al, PNAS (USA), 2012

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PALEO-COSMIC RAYS - A PROXY FOR SPACE CLIMATE

High PCR (“Maunder”) Low PCR (“Modern”)

Low sunspot cycles High sunspot cycles Low solar activity High solar activityLow HMF High HMFHigh radiation environ’t Low radiation environ’t

OTHER SEQUENCES OF GRAND MINIMA- AND >1000 YR LONG INTERVALS BETWEEN

MS

M

M

S M

M

D

D D

McCracken and Beer, JGR, 2014

Dye 3 and North GRIP Annual Data

THE MAUNDER MINIMUM – UP CLOSE.

McCracken and Beer, JGR, 2014

COSMIC RAYS- A COSMIC MAGNETOMETER

After Caballero - Lopez et al, 2004

Modulation Potential (Observed)

Φ = k. VP . B2(t) / ˂(ΔB)2˃

Helio-magnetic field (inferred)

B(t) = B0 . {Φ(t)/ Φ0} 1/α

The HMF (Omni-2) near Earth , 1975-2009

Bmax

BminBmax/ Bmin= (1.31-1.63)Average = 1.52

COMPARING THE SOLAR DYNAMO DURING MAUNDER MINIMUM WITH THE PRESENT

MODERN MAUNDER

Bmax/ Bmin 1.31-1.63 1.30-1.85

Average 1.52 1.54

CONCLUSION- A remarkable similarity- the solar dynamo apparently worked then like now with much weaker magnetic fields.

Name Duration Rise Cycles Peak NM(%) Min.HMF(nT) Spoerer 1440-1540 4 111.3 2.4Maunder 1645-1715 5 117.0 <2.0Dalton 1790-1830 2 110.9 2.6Gleissberg 1880-1910 104.5 3.8

Extended Minimum 2006-9 102.8 3.9

Modern epoch Minima 1954-96 97.7 5.4

Comparison of key features of the Minima

COMPARISON OF EXTENDED SUNSPOT MINIMUM 2006-9 AND GRAND MINIMA, 1400-1850 AD.

- The cosmic ray intensity during 2006-9 was well below those in the Spoerer and Maunder Minimum, while approaching that in the Gleissberg Minimum.

- The cosmic ray intensity increased over 4 to 5 solar cycles at the commencement of the Grand Minima.

- The next solar minimum 2019 will determine whether the Sun is going into another Grand Minimum.

-The solar dynamo operated during the Maunder Minimum as it does today

THANK YOU

Steinhilber et al, PNAS (USA), 2012

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THE SEQUENCE OF GRAND MINIMA-950-2000 AD - OUR CALIBRATION ERA.

In “Grand Minimum” ~40% of time!

Space Era Level