紫金山天文台55 yr手绘黑子数据系统差分析

对紫金山天文台(简称紫台)自1954年至2011年共55 yr的手描黑子图进行了数字化.将紫台太阳黑子相对数(PRSN)和黑子群数(PGSN)与国际太阳影响数据分析中心(SIDC)中的对应数据(月平均太阳黑子相对数(IRSN)和月平均黑子群数(IGSN))进行对比研究,发现:(1)紫台黑子数据与SIDC黑子数据有很强的正相关性,说明紫台黑子数据的可靠性;(2) PRSN和IRSN、PGSN和IGSN的系统偏差分别处于7%左右、5%左右,紫台数据与SIDC数据在活动周的极小期的差异性显著大于极大期;(3)紫台的视宁度从1995年开始变差,直接导致了PRSN (PGSN)与IRSN (IGSN)的比值明显变大,表明视宁度的变化影响了紫台黑子的观测质量.

System Difference Analysis for the 55 Years' Hand-drawing Sunspot Data of Purple Mountain Observatory

The hand-drawing sunspot records of the Purple Mountain Observatory(PMO)from March 1954 to December 2011 are digitized completely.In this paper,we compare relative sunspot number(PRSN)and group sunspot number(PGSN)of the PMO with the corresponding data from Solar Influences Data Analysis Center(SIDC),namely the relative sunspot number of SIDC(IRSN)and the group sunspot number of SIDC(IGSN),respectively.It is found that there is a strong positive correlation between the sunspot data of the PMO and the SIDC,which indicates the reliability of the PMO sunspot data.When comparing PRSN with IRSN and contrasting PGSN with IGSN,the system difference is about 7 percent and 5 percent,respectively.The difference in the minimal period of solar active circle of the PMO and SIDC sunspot data is significantly greater than that in the maximal period.The visibility of the PMO became worse since 1995,which directly leads to a significant increase in the ratio of PRSN(PGSN)to the IRSN(IGSN).It indicates that the change of visibility affects the observation quality of the PMO sunspot data.