基于Holt指数平滑模型的Klobuchar模型精化

利用IGS（International GNSS Service）中心提供的中、低纬度地区平静期、活跃期观测数据，通过Klobuchar模型与双频观测模型解算电离层总电子含量（total electron content，TEC）值。采用Holt指数平滑模型对每个历元前6 d两种模型差值进行1 d预测，利用预测所得差值对Klobuchar模型第7 d的TEC值进行改进。实验结果表明，无论在电离层活跃期还是平静期，改进模型改正效果比基本模型有显著提升，改进模型能更好地反映电离层变化特性，尤其是夜间电离层变化特性。

A Sophisticated Klobuchar Model Based on the Holt Exponential Smoothing Model

We use Klobuchar model and Dual-frequency observation model to calculate TEC values with the data provided by IGS center over low-latitude and mid-latitude areas in ionospheric quiet period and active period. Then improve 7th day's TEC values calculate by Klobuchar model with the difference values come from the forecast difference values in each epoch of the preceeding 6 days between Klobuchar model and Dual-frequency observation model by the Holt exponential smoothing model. The experiment results show that the correction effect of improved model has a significant improvement than the basic model no matter whether it is in in ionospheric quiet period or active period. In addition, the improved model can better reflect the ionospheric changing characteristics, especially the night ionospheric changing characteristics.