基于IRI-2012模型广州地区f_0F_2实测与预测的对比分析

Comparison of f_0F_2 between Observation and the Prediction Based on IRI-2012 over Guangzhou

利用广州台站(23.2°N,113.3°E)的实测数据和IRI-2012模型提供的预测数据,对比分析了2013年广州地区f_0F2的变化特征.结果表明,IRI-2012模型能够较好预测该地区f_0F_2的变化趋势,并且CCIR参数得到的预测值比URSI参数更接近实测值;预测值与实测值存在系统偏差,在11:00 LT-06:00 LT时段,观测值均比预测值大,其他时段则相反.在日落后至午夜前时段,预测值与实测值有较大差距.绝对偏差的极值点通常出现在20:00 LT左右,最大超过4 MHz.相对偏差变化比较明显的时段是午夜后至凌晨;在02:00 LT或04:00 LT及06:00 LT附近,可能会出现双误差峰值点,最大超过0.4;但在σ变化很大的20:00 LT附近,相对偏差却变化不大.夜间增强现象会使得偏差增大,导致预测值不能很好反映实测f_0F2的变化.

Monthly mean values of f_0-F_2 parameter,with an hour time interval resolution for diurnal variation,obtained at Guangzhou(23.2°N,113.3°E) station are used to investigate the variations and comparisons with the International Reference Ionosphere(IRI-2012) model predictions.The results show that generally,IRI-2012 predictions follow well with the diurnal and seasonal variation patterns of the observed values of f_0F_2,and the predictions with CCIR coefficients is better than URSI.However,there are systematic deviation between observed values and IRI predictions with either CCIR or URSI coefficients.Generally IRI model greatly underestimates the values of f_0F_2from about noon to sunrise of the next day,especially at 20:00LT,and slightly overestimates them from sunrise to about noon.The deviation will increase at the time when the nighttime enhancement occurred,especially in spring and autumn.This means that the predictions can not follow well with variation of the observed values of f_0F_2.