The sunspot activity before 17th century

0 0 8 3 - 6 6 $ 6 / 8 8 $0.00+ .50 Copyright © 1988 Science Press & Pergamon Journals Ltd,

Vlatasin Astronomy, Vol. 31, pp. 119--122, 1988

THE

SUNSPOT

Purple

ACTIVITY

BEFORE

17TH

Xu Zhentao Chen Mountain Observatory~

Dept.

of

Bing Nanjing~

Jiang Yiaotiao Astronomy, Nanjing

The variability of solar activity before interesting problem (Eddy,

CENTURY

Univ.,

China China

17th century has been an

1978). During this historical period,

Chinese ancient sunspot records observed by naked eye were unique direct reflections of solar activity,

so many authors used them to

analyse the periodicity of solar activity (Xu, on theonehandtheir

1983). However,

sunspot catalogs were incomplete,

and on the other

hand the weight of different sunspot records was not considered,

so

these studies could be improved further. We have attempted to overcome these shortcomings, I: Data and Weighting.

and do so as follows: We selected the naked-eye sunspot

catalog presented by Wittmann and Xu (Wittmann and Xu,

1987) which

is the most complete sunspot catalog as a basis for this analysis. According

to descriptive

difference of sunspot size, number and

duration we have given different weight for every sunspot record. Thus we have transformed descriptive

sunspot records into a numerical

time series. 2: Calculation. numerical table

time series of sunspot records and obtained the following

and Fig. l: 2o 28s O. 142

We have done a power spectrum analysis for the

l

516

7s4

lox2

126o

,5os

r

f

,

I

r

175o '

2004

r

Fig. l Periodogr~ o~ time series.

Power Spectrum O. 107

O. 072

0.037

0.002 FREQUENCE(0.000!/YEARS)

119

120

Xu Zhentao et al. Frequence

Period

Phase

Amplitude

(C/Years) 0.0038 0.0047 0.0159 0.0024 0.0942 0.1506 0.0090 0.0114

(Years) 263.16 212.77 62.89 416.67 10.62 6.64 110. 10 86.96

1.3251 0.0267 -0.2926 ~0.7763 -1.5087 -0.8893 -0.0031 0.5784

0.2448 0.2555 0.1352 0.1279 0.1156 0.0858 0.0856 0.0694

3: Discussions.

(I): The

10.62 year cycle actually

is the mean

period of Schwabe's cycle and it accorded with studying results of many authors

(Chernosky,

even if the ancient Schwabe's

1966; Currie,

sunspot records could not be successive,

cycle signal

is quite significant

cal period of nearly two millenia with Schwabe's opinions

1974). This has shown well ~at

solar activity regularly varied

cycle and never stopped.

concerning

and during the histori-

(2): There were two kinds of

the formation of the Maunder

Minimum.

Eddy

(1976) thought that it was caused by the stopping of the magnetohydrodynamical

dynamo of solar activity,

that it was a consequence solar activity.

of the influence

We separately analysed

of every

on the Maunder Minimum

that the Maunder Minimum may be a consequence

superposed variations activity.

claimed

of long term periods of

the influences

long-term period and their combinations and have concluded

but Link(1978)

of

of several long-term periods of solar

The period with mean length equal to 238 year may play an

important role in the formation of the Maunder Minimum ~uring this historical activity separately

(see Fig.2).

(3):

period the two weakest epochs of solar

corresponded

to AD 400 and AD 1170 (see Fig.3).

After comparing with the atmospheric

temperature

curves of China

and Greenland (~u 1973) and the frequency curve of the Oriental aurora, we have found that these t~o epochs just locate in the lowest parts (see Fig.4).

of these curves,

particularly

for the epoch of AD 400

This means that in these two epochs or intervals

solar activity

fell to its lowest minima.

these two epochs is nearly 800 years.

the

The difference between

If this means that there is a

period of solar activity with a length of nearly 800 years, maybe mankindwill century.

face the threat of little ice age in the late twentieth

The Sunspot Activity

~o

213

425

637

i

f

I

849

1061

1273

121

1485

1697

Fig.2 The Superposed variation of two cycle with periods 263 and 212 yrs.

L60

120

4o

i!, .i

o

WAVELENGTH(YEARS)

Fig.3 The solar varia- ~0 tion of near 2000 yrs.

213

425

637

849

1061

{

i

i

+

i

1273

1485

160

120

i

80 I 40

0

1

t

r

,I

l

I

i

WAVELENGTH(YEARS)

+2of i++r pre++emp++j -2"C

I-

l:il

.

_

°. -.~8 ~.. l~J .~

.......... "-It:/ . . . . . . . """

~L

--~.o

..

o

"

~ °

~ o

.. , , !! "-~ "-.-"" ;:: t: "'~: .-~, .:

~

~

:~ :

~

%!

~ ~._

i :

~

~.

;'.:

-.J

";-"-':4 ~.:

~

Fig.4 The World temperature variations of 1700 yr before present (upper: from Chinese Phenology) (lower: from Greenland ice cores)

1897

122

Xu Zhentao et al.

REFERENCES Eddy. J.A., (1978). The New Solar Physics, (Westview Press, Boulder), p.51 XUo Z.T. (1983). Proc. Internat. workshop on Solar Phys. a n d Interplan. Tray. Phen., I, 108 Wittmann, A.D. and Xu, Z.T. (1987), Astron. Astrophys. Suppl. Set., 70, 83 Chernosky,E. J., (1966), J.Geophys. Res., 71, 965 Currie, R. G. (1974), J. Geophys. Res., 79, 5657 Eddy, J.A., (1976), Science, 192, 1189 Link, F., (1978), Solar Physics, 59, 175 Zhu, K. Z. (1973), Scientia Sinica, "16(2), 226