An ionospheric assimilation model along a meridian plane

• An assimilation model based on the theoretical ionospheric model was constructed.
• The critical parameters NmF2 and hmF2 are assimilated into the model.
• The assimilation model based on few observations can well produce assimilated results.
• Except for NmF2 and hmF2, the assimilation model can also adjust total electron content.

In this paper, we developed a two-dimensional ionospheric assimilation model that assimilates the observations of peak electron density of F2-layer (NmF2) and the peak height of F2-layer (hmF2) derived from five ionosonde stations along the 120°E meridian, using three-dimensional variation techniques (3DVAR) based on a physics-based ionosphere theoretical model. The assimilation system can well produce the assimilated results along the 120°E meridian plane by using the data of NmF2 and hmF2 at five ionosonde stations from Mohe (52.0°N) to Sanya (18.3°N). The root mean square error (RMSE) between the analysis results of the assimilation model and the ionosonde observations is much lower than that between the results from international reference ionosphere (IRI) and the ionosonde observations. In addition, we carried out the assimilation test by taking the IRI results as the observations to check the assimilated results in the regions without observations. The assimilated result in the southern hemisphere (RMSE=0.29) is much worse than that in the northern hemisphere (RMSE=0.10) because no observations in the southern hemisphere were used. If the data derived from the four ionosonde stations in Australia are used, the assimilated result in the southern hemisphere would be much more accurate. In addition to NmF2 and hmF2, the assimilation model can also adjust the total electron content (TEC). The RMSE between the TEC after assimilation and the observed GPS TEC is much lower than that between the TEC from the IRI model and the observed GPS TEC.