Extracting Exospheric Temperature From Daytime Ionospheric Electron Density Profiles

Abstract

Given that the ionosphere is strongly determined by the thermosphere and its state depends on thermospheric parameters, we propose a new method to extract exospheric temperature (Tex) from electron density (Ne) profiles based on the relationship between the variations in Tex and Ne profiles established through simulation. Ne profiles and corresponding Tex from the Millstone Hill incoherent scatter radar (ISR) observations are used to test the method. ISR Ne profiles are used for Tex retrieval and ISR Tex is used to make a comparison with Tex calculated by model and retrieved Tex. The results show that the retrieved Tex effectively captures diurnal, anomalous and short‐period variations. The relative deviation between the retrieved–observed Tex is approximately 2%, which is significantly improved compared with the Mass Spectrometer Incoherent Scatter model, especially under disturbed conditions. This result confirms that thermospheric temperature variation can be deduced from ionospheric profiles and our method can be considered a useful tool to obtain Tex from Ne profiles.

The Daytime Variations of Thermospheric Temperature and Neutral Density Over Beijing During Minor Geomagnetic Storm on 3–4 February 2022

“…Currently, a large amount of ionospheric observation data has been accumulated through ionosonde, ISR and satellite radio occultation. The method proposed by Li et al (2023) provides a method to obtain thermospheric information from ionospheric observations. Based on the continuous ionogram data of 15-min temporal resolution provided by ionosonde, we can analyze in detail the responses of the thermosphere to geomagnetic storm during daytime, including the variations with local time, duration, magnitude of perturbations, etc.…”

“…Consequently, the electron density in the F 1 layer is mainly controlled by the surrounding neutral atmosphere and the EUV flux. The state of the ionosphere at the F 1 layer height, in turn, contains valuable information about the surrounding thermosphere (Li et al, 2023;Perrone & Mikhailov, 2018). To obtain variations in the thermosphere from ionospheric observations, we follow the methodology outlined in Section 2 of Li et al (2023).…”

“…The state of the ionosphere at the F 1 layer height, in turn, contains valuable information about the surrounding thermosphere (Li et al, 2023;Perrone & Mikhailov, 2018). To obtain variations in the thermosphere from ionospheric observations, we follow the methodology outlined in Section 2 of Li et al (2023). The central concept of the method is establishing a functional relationship between the variations in Tex and electron density profiles through numerical simulations.…”

“…Then, these electron density profiles are fitted to reduced height Z and neutral density [n] calculated by the NRLMSISE-00 model to determine fitting coefficients. From the derived Equation 6 in Li et al (2023), the fitting coefficient f Z is equal to 1. Since there are differences between the true values and the NRLMSISE-00 model values of [n] and Z, the fitted coefficients will inevitably contain deviations.…”

“…Hence, it is difficult to study temporal variations in the thermosphere. In this study, we adopt the method proposed by Li et al (2023) to extract exospheric temperature (Tex) from daytime electron density profiles (∼150-200 km). Ground-based ionosonde observations at Beijing (geolocation: 39.56°N; 116.2°E; geomagnetic location: 30.16°N; 172.08°W) station were selected here to derive the Tex.…”