An empirical model of the topside plasma density around 600km based on ROCSAT-1 and Hinotori observations

摘要

abstract_textpIt is an urgent task to improve the ability of ionospheric empirical models to more precisely reproduce the plasma density variations in the topside ionosphere. Based on the Republic of China Satellite 1 (ROCSAT-1) observations, we developed a new empirical model of topside plasma density around 600 km under relatively quiet geomagnetic conditions. The model reproduces the ROCSAT-1 plasma density observations with a root-mean-square-error of 0.125 in units of lg(Ni(cm(-3))) and reasonably describes the temporal and spatial variations of plasma density at altitudes in the range from 550 to 660 km. The model results are also in good agreement with observations from Hinotori, Coupled Ion-Neutral Dynamics Investigations/Communications/ Navigation Outage Forecasting System satellites and the incoherent scatter radar at Arecibo. Further, we combined ROCSAT-1 and Hinotori data to improve the ROCSAT-1 model and built a new model (RH model) after the consistency between the two data sets had been confirmed with the original ROCSAT-1 model. In particular, we studied the solar activity dependence of topside plasma density at a fixed altitude by R H model and find that its feature slightly differs from the case when the orbit altitude evolution is ignored. In addition, the R H model shows the merging of the two crests of equatorial ionization anomaly above the F-2 peak, while the IRI_Nq topside option always produces two separate crests in this range of altitudes./p/abstract_text