## 6 Conclusions  
In situ \(N_{\rm e}\) observations by LPs onboard CSES--01 and Swarm B satellites have been used to characterize the global behavior of the effective scale height (\(H_{0}\)) at the F2-layer peak. For the F2-layer peak anchor point, we used values modeled by the latest version of IRI, i.e., IRI--2020. The dataset used in this study allowed for the investigation of the \(H_{0}\) global behavior for both daytime and nighttime conditions, different seasons, and low solar activity. The main results of this work can be summarized as follows:  
1. For daytime conditions, \(H_{0}\) values modeled using CSES--01 and Swarm B calibrated observations agree with corresponding values obtained directly from COSMIC--1 RO profiles, which is our reference. The geomagnetic equator is where the most relevant differences are present. There, values modeled through both CSES--01 and Swarm B observations are much higher than those obtained through COSMIC--1. Instead, during nighttime, \(H_{0}\) values obtained from both CSES--01 and Swarm B-calibrated observations show large differences compared to those obtained through COSMIC--1. Such differences are spatially localized in several latitudinal belts at both low and mid latitudes, where \(H_{0}\) values obtained from both CSES--01 and Swarm B show values much higher in magnitude than those from COSMIC--1. 2. \(H_{0}\) values obtained with non-calibrated CSES--01 and Swarm B observations differ substantially from those obtained with calibrated observations. Except for the Swarm B daytime sector, \(H_{0}\) values from non-calibrated observations show either highly underestimated or overestimated values, which, in most cases, are unphysical. This is an independent piece of evidence that suggest that, for the local times and low solar activity conditions studied in this paper, both CSES--01 and Swarm B LP \(N_{\rm e}\) observations need to be calibrated before being used for ionospheric modeling. 3. Most of the \(H_{0}\) mismodeling for nighttime conditions seems to be caused by a sub-optimal spatial representation of the F2-layer peak density made by the IRI model. This issue could be attributed to the IRI spherical harmonics numerical mapping procedure underlying the \(Nm\)F2 spatial representation, which shows some limitation during nighttime hours. However, the issue is not present for daytime hours. This highlights the importance of an accurate characterization of the F2-layer peak anchor point in topside ionosphere modeling. The methodology developed in this study for the topside effective scale height modeling turns out to be applicable to any in situ \(N_{\rm e}\) observation made by LEO satellites orbiting in the topside ionosphere. At the same time, the reliability of the method is critically dependent on the accurate knowledge of both the topside anchor point and the F2-layer peak anchor point. This is an undoubted disadvantage when compared to the methodologies which make use of the full topside \(N_{\rm e}\) profile provided by RO observations [6; 25; 51; 61]. However, when accurate data are available, both spatial and time variations of the topside effective scale height can be reliably described. In this study, the topside effective scale height variations due to the solar activity and geomagnetic disturbed conditions have not been investigated due to the limited dataset encompassing only low solar activity and fairly geomagnetically quiet conditions. As a future development, we plan to extend this study by also considering different solar activity and geomagnetic activity conditions when enough satellite observations will be available during the upcoming solar activity maximum. The ever-increasing number of LEO satellites performing in situ \(N_{\rm e}\) observations in the topside ionosphere makes the applicability of this methodology promising for topside ionosphere modeling.