Comparison between IRI and preliminary Swarm Langmuir probe measurements during the St. Patrick storm period

Abstract

Preliminary Swarm Langmuir probe measurements recorded during March 2015, a period of time including the St. Patrick storm, are considered. Specifically, six time periods are identified: two quiet periods before the onset of the storm, two periods including the main phase of the storm, and two periods during the recovery phase of the storm. Swarm electron density values are then compared with the corresponding output given by the International Reference Ionosphere (IRI) model, according to its three different options for modelling the topside ionosphere. Since the Swarm electron density measurements are still undergoing a thorough validation, a comparison with IRI in terms of absolute values would have not been appropriate. Hence, the similarity of trends embedded in the Swarm and IRI time series is investigated in terms of Pearson correlation coefficient. The analysis shows that the electron density representations made by Swarm and IRI are different for both quiet and disturbed periods, independently of the chosen topside model option. Main differences between trends modelled by IRI and those observed by Swarm emerge, especially at equatorial latitudes, and at northern high latitudes, during the main and recovery phases of the storm. Moreover, very low values of electron density, even lower than 2 × 10 4 cm −3, were simultaneously recorded in the evening sector by Swarm satellites at equatorial latitudes during quiet periods, and at magnetic latitudes of about ±60° during disturbed periods. The obtained results are an example of the capability of Swarm data to generate an additional valuable dataset to properly model the topside ionosphere.

Modeling the Lower Part of the Topside Ionospheric Vertical Electron Density Profile Over the European Region by Means of Swarm Satellites Data and IRI UP Method

“…The NeQuick topside option of IRI has been chosen because, when compared to the other two possible options proposed by IRI, it turns out to be the best one (Bilitza, ). Moreover, as it has been shown recently by Pignalberi et al (), the IRI topside description performs better for midlatitudes; this is why we expect that this IRI topside option is a good point of comparison. Table points out that the α‐Chapman topside profile is the best one compared to both the other topside profiles studied and the IRI‐NeQuick topside model, by using both Swarm A and C and Swarm B‐derived effective scale heights.…”

“…A further IRI topside option, based on the NeQuick topside formulation (Coisson et al, ; Radicella & Leitinger, ), was introduced later to improve some shortcomings (Bilitza, ). Despite these huge efforts, the topside modeling in IRI is still a challenge, as it was recently demonstrated by Pignalberi et al (), who made a comparison between electron density values in the topside part of the ionosphere measured by Swarm satellites and calculated by IRI.…”

Formation of ionospheric irregularities over Southeast Asia during the 2015 St. Patrick's Day storm

“…Depending on the geographical sector and time of the day, such difference ranges in the order of 8% to 15% [Pedatella et al, 2015;Pignalberi et al, 2016]. N e measured by Swarm at altitudes between 450 and 550 km has two characteristics: first, it is an in situ measurement and second, it is made in the topside ionosphere.…”

A new parameterized approach for ionospheric tomography

“…Swarm, a European Space Agency mission, consists of three identical satellites to study the earth's magnetic field (Olsen et al 2013). The Swarm A and C satellites are flying side by side at the same altitude of about 450 km and the Swarm B satellite is placed at an orbit of about 510 km (Pignalberi et al 2016). To further validate the tomographic IEDs, we adopted the Langmuir data from the three Swarm satellites from June 1-30, 2015 as a reference.…”