Testing of new ionospheric models along the meridian 110°E over the Northern Hemisphere

Despite the continuous improvement of the widely used empirical model international reference ionosphere(IRI),the recently appeared new models must be tested worldwide.Testing along the meridians has the advantage of dealing with the latitudinal dependent parameters.This paper uses new models of parameters foF2(critical frequency),TEC(total electron content),andτ(equivalent slab thickness of the ionosphere),which are of great importance for evaluating the effects of space weather.IRI-Plas,NNT2F2,and NTSM models were tested using data from 6 ionosondes located along the meridian 110°E in March 2012.It is shown that the IRI-Plas model provides the closest values to experiment with respect toτ,while the NTSM model provides a rather limited reflection of the latitude dependence.Analyses of foF2(NNT2F2)have shown that,the NNT2F2 model provides good conformity with experimental values in this area,but it is very dependent on the TEC processing method.The latitudinal dependences of foF2 obtained with TEC and polynomial dependenceτ(Appr)showed the presence of positive deviations from medians not only during disturbances but also quiet periods,longitudinally at the meridian.

The effect of space weather on the ionosphere at the 110°meridian during CAWSES-Ⅱperiod

Space weather determines the state of the ionosphere,which is especially important to know during disturbances.To study this state,the period of March 7-17,2012,which was recommended by SCOSTEP for detailed studies and called CAWSES-II,was selected.In this period,the behavior of parameters of the solar wind(SW)and the interplanetary magnetic field(IMF)show a number of features.In this paper,we study their relationship with the total electron content(TEC)and the critical frequency(foF2)of the ionosphere at the 110°meridian,near which several ionosondes are located,in the range of 20°N-62.5°N.The correlation coefficients of TEC and foF2 with the SW and IMF parameters for the month and the selected period are calculated.The ionosphere showed the considered disturbances in different ways in different latitudinal zones:negative anomalies are observed at high latitudes,and positive ones at low latitudes.A distinctive feature is the presence of signs of a super-fountain effect.Deviations of TEC and foF2 from their medians can be significant.The IRI model reacted in the latitude range 40°N-62.5°N in the form of negative anomalies,although positive anomalies were observed in the TEC.At lower latitudes,no reaction was observed.For all factors(F10.7,Dst,Kp,IMF,Np),three zones(high-latitude,midlatitude,and low-latitude)are distinguished for different coefficients.The strongest influence of disturbances on the correlation coefficients is observed in the zone of 37.5°N 62.5°N.