Abstract

This paper presents the results of a coordinated measurement campaign with ground based and satellite observations over European and Japanese regions during September 5–6, 2017. Two incoherent scatter radars, two satellite missions, International Reference Ionosphere (IRI-2016) empirical model, and Field Line Interhemispheric Plasma (FLIP) physical model were employed to examine the regular behavior of the F2-layer peak height and density and the topside ionosphere electron density, electron, and ion temperatures as well as traveling ionospheric disturbances (TIDs). The daily ionospheric variations over Kharkiv and Shigaraki exhibited similar behavior qualitatively and quantitatively. The results show that none of the empirical IRI-2016 models of F2-layer peak height, topside electron density, and temperature can be preferred for predicting the key qualitative features of variations in ionospheric plasma parameters over Kharkiv and Shigaraki. The likely reason is rapid day to day changes in solar activity and series of moderate enhancements of magnetic activity occurring in the observation period and preceding days. Compared with IRI-2016 model, the FLIP physical model was shown to provide the best agreement with the observations when constrained to follow the observed diurnal variations of F2-layer peak height both over Europe and Japan. This paper presents the first direct comparison of the mid-latitude electron density measured by the Swarm satellite with incoherent scatter radar data and it confirms the high quality of the space-borne data. For the first time, evidence of the possible need to increase the neutral hydrogen density in NRLMSISE-00 model by at least a factor of 2 was obtained for the Asian longitudinal sector. The TIDs, which have predominant periods of about 50 min over Europe and 80 min over Japan, were detected, likely caused by passage of the solar terminator. Such a difference in the periods could indicate regional features and is the topic for further research.

Highlights

  • Knowledge about the characteristics of geospace environment all over the world is necessary for understanding and predicting space weather phenomena during different solar and magnetic activity conditions

  • Buresova et al (2014) revealed that minor and moderate storms occurring during very low solar activity conditions can cause variations in the F2 peak electron density (NmF2) and height that can rival those observed during strong magnetic activity

  • The magnitude of the diurnal change of hmF2 is largest for Shigaraki

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Summary

Introduction

Knowledge about the characteristics of geospace environment all over the world is necessary for understanding and predicting space weather phenomena during different solar and magnetic activity conditions. Strong space weather events such as severe and extreme magnetic storms are known to result in significant variations in ionosphere and thermosphere (IT) parameters and often have negative effects on human infrastructure, especially, on space-based assets (see, e.g., Hapgood (2011); Tsurutani et al (2012)). Buresova et al (2014) revealed that minor and moderate storms occurring during very low solar activity conditions can cause variations in the F2 peak electron density (NmF2) and height (hmF2) that can rival those observed during strong magnetic activity. Kotov et al (2018); Kotov et al (2019) reported a significant decrease (factor of 2) in plasmaspheric density that was induced by a very weak magnetic disturbance and strong modulation of the ionosphere-plasmasphere H+ ion fluxes that causes strong variations in the ion composition of the topside ionosphere. Trigger mechanisms of energy release can play a decisive role due to the highly nonlinear IT response to the external influence (Chernogor 2011)

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