太阳活动周的3个参量：AS,BT和BW

通过对１２－２２周（（１８７８－１９９５年）太阳大黑子群分布南北半球不对称的整体特征的研究，探讨了太阳活动周的长期演化趋势．约定Ｎ与Ｓ分别表示北南半球大黑子群数之和，ＢＮ与ＢＳ为北南半球大黑子群的纬度和．由这４个物理量定义了太阳活动周的３个参量：（１）太阳活动不对称指数ＡＳ＝（Ｎ－Ｓ）／（Ｎ＋Ｓ）；（２）平均纬度ＢＴ＝（ＢＮ＋ＢＳ）／（Ｎ＋Ｓ），ＢＳ取负值；（３）太阳活动带的宽度ＢＷ＝ＢＮ／Ｎ－ＢＳ／Ｓ．对上述１１个活动周，得到了有关８０年周期的性质及奇偶数周大黑子群数变化的有意义的统计结果．

THREE PARAMETERS OF THE SOLAR CYCLE: A S, B T AND B W

In this paper,the long term evolutionary trend of solar cycles is investigated on the basis of a statistical analysis of the north south asymmetry of the large sunspot groups in solar cycles Nos.12-22(1978-1995).The numbers of large spot groups in northern and southern hemispheres are denoted by N and S ,while the sums of spot groups' latitudes- B N and B S,respectively.Then three parameters are defined with the above four quantities, i.e. (1) the asymmetry index A S= (N-S)/(N S); (2) the average latitude B T=( B N B S)/( N S) ,where B S is negative;(3) the width of activity belt B W= B N/ N - B S/ S . The above mentioned 11 solar cycles yield the following statistical results.(1) The distributions of signs of A S and B T can be divided into three intervals:the 14th-20th cycles fall into positive intervals,while the other 4 cycles-negative ones.(2) When A S and B T are positive,the values of N-S for odd cycles are larger than those of the neighboring even cycles.When A S and B T are negative,the absolute values of N-S of even cycles are larger than those of odd ones.(3) When the absolute value of A S approaches 0.33 ( i.e.N/S or S/N is close to 2), A S changes sign.(4) B W exhibits a systematic evolution from its minimum,increasing at first and decreasing afterwards,in the time interval of 7 cycles. From the evolutionary trend of cycles Nos.12-22,it is speculated that the 23rd cycle would possess a southern hemisphere dominance in large sunspot activity.