纬度因素对季节性时序TEC短期预报模型的影响分析

Analysis of the Influence of Latitude Factors on Seasonal Time Series TEC Short-Term Forecast Model

通过测试选取合适的时间序列长度,分析地磁指数,排除磁暴与地磁活动的影响,针对电离层TEC值的周期性变化及其随纬度的不均匀分布规律,采用季节性时间序列模型SARIMA和指数平滑模型HoltWinters,利用IGS中心提供的TEC格网数据,对北半球不同纬度的48个区域进行预报,并通过定义日均相对精度和均方根误差来评定预报精度。结果表明,3种模型均能较好地反映电离层TEC值的周期性变化,但均方根误差随纬度的降低总体呈现增长趋势,且在北纬25°与55°表现为极大值,在北纬45°表现为极小值。

By testing the length of time series, the influence of geomagnetic index on the exclusion of geomagnetic activity and geomagnetic activity is analyzed. For the periodic variation of the TEC value of the ionosphere and its inhomogeneous distribution with latitude, we use the seasonal time series model, SARIMA and the Holt-Winters exponential smoothing model. 48 regions of different latitudes of the northern hemisphere are predicted using the TEC grid data provided by the IGS Center, and the daily mean relative accuracy and root mean square error are defined to assess forecast accuracy. The results show that all three models can reflect the cyclical changes of ionospheric TEC values, but the root mean square error decreases with the latitude and shows an overall trend of growth; at 25° and 55° north latitude it shows a maximum value, while at 45° N, it shows a minimum value.