基于太阳活动“相似周”的第25太阳周期F_(10.7)预报  

Forecasting the F_(10.7) of solar cycle 25 using a method based on"similar-cycle"

作　　者：李修贤 李敏[1] 蒋科材 LI XiuXian;LI Min;JIANG KeCai(Research Center of GNSS,Wuhan University,Wuhan 430079,China;School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China)

机构地区：[1]武汉大学卫星导航定位技术研究中心,武汉430079 [2]武汉大学测绘学院,武汉430079

出　　处：《地球物理学报》2023年第9期3623-3638,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42074032,42204020);中央高校基本科研业务费专项资金(2042021kf0063);博士后面上基金(2021M702507)资助。

摘　　要：太阳辐射指数F_(10.7)是衡量太阳活动强度的重要参数,在构建高层大气模型、电离层建模、空间通信等方面发挥着重要作用.为满足应用场景对F_(10.7)预报长期性、简便性的要求,本文研究了基于太阳活动“相似周”的F_(10.7)指数长期预报方法.利用历史周期的相似性构造F_(10.7)变化趋势预测线,并对其进行最小二乘拟合得到预报目标周期F_(10.7)长期变化趋势的公式.本文对相似周数据处理过程进行了系统性说明,并通过最小二乘拟合过程将经验公式法可量化、易表达的优势融入到“相似周”法中,建立的预报公式仅有时间参量,可简便而且准确地预报F_(10.7).通过对第24周进行预报实验,得到以下结论:(1)该方法预报结果平均相对误差为12.69%,与现有经验公式62.08%的平均相对误差相比,精度显著提升;(2)在太阳周期内的大部分年份,该方法可较好地满足F_(10.7)长期趋势预报的需求,在太阳活动高峰年平均相对误差为16.82%,较现有经验公式精度提升一倍.进一步地,给出第25太阳周期F_(10.7)的预报公式,截至2022年8月31日,该公式预报平均相对误差为8.77%.The solar radio flux at F_(10.7) is a key indicator of solar activity.It plays an important role in building the upper atmosphere model,ionosphere modeling,and space communication.In order to meet the requirements of the applications for the long-term and simple forecast of F_(10.7),we have established a forecasting method for the daily value of F_(10.7) based on the"similar cycle"of solar activity in this study.With similar characteristics of historical periods,we can construct the F_(10.7) variation trend prediction line,and then fit the parameters of the forecasting formula for the long-term variation trend of F_(10.7) in the target period by the least squares method.In this study,we systematically introduce the processing method for similar cycles,which incorporates the advantages of easy expression and quantification of the empirical formula method.The prediction formula only takes time as the independent variable,which can calculate F_(10.7) values simply and efficiently.Through the experiment in Solar Cycle 24,the formula is tested and the results as follows:(1)The mean relative error of the prediction of this method is 12.69%,which is significantly lower than that of the existing empirical formula with 62.08%;(2)In main years of a solar cycle,this method can meet the needs of F_(10.7) long-term trend forecast with the mean relative error of only 16.82%,even in high solar activity year,which is about twice as accurate as the existing empirical one.Furthermore,we have given the fitting parameters of the prediction formula in Solar Cycle 25 for F_(10.7).As of August 31,2022,the mean relative error of the prediction is only 8.77%.

关 键 词：F_(10.7) 长期预报 相似周 经验公式 

分 类 号：P353[天文地球—空间物理学]