Abstract
Height distribution of ionospheric plasma parameters in the F2-region is closely related to height distribution of the main thermospheric parameters. Therefore, they can be extracted from ionospheric observations solving an inverse problem of aeronomy. A self-consistent approach to the Ne(h) modeling at the F2-region heights has been applied to solve the problem. Using routine incoherent scatter radar observations (Ne(h), Te(h), Ti(h), Vi(h) profiles) the method yields a self-consistent set of main aeronomic parameters responsible for the F2-region formation. The list of derived parameters includes: neutral temperature profile Tn(h) depending on the exospheric temperature Tex, the temperature at 120 km T120 and the shape-parameter S, which determine the temperature profile, concentration of neutral species [O], [O2], [N2], vertical plasma drift W, which may be converted to the meridional thermospheric wind Vnx, total solar EUV flux and ion composition (O+, O2 +, NO+, N2 +, N+) as a result of Ne(h) fitting. Therefore, the method gives a complete description of the upper atmosphere condition in the vicinity of incoherent scatter facility for the periods of observation. Analysis of all available EISCAT (CP-1, CP-2) observations has shown wide deviations from MSIS-86 model predictions for geomagnetically disturbed conditions while the retrieved parameters are close to the model ones for quiet periods. The approach turns out to be very useful for physical analyses of the F2-layer disturbance mechanisms giving a complete picture of the phenomenon in question. Limitations and problems related to method application are discussed. Under existing conditions when thermospheric observations are not conducted currently the proposed method may be considered a real tool for thermosphere investigation and monitoring at least for the periods of ISR observations.
Highlights
The idea of using ionosphere plasma parameter observations to obtain various aeronomic parameters has been implemented and used since the beginning of ionospheric research
Ionospheric observations are widely used to obtain thermospheric parameters: winds (Mikhailov and Ostrovskii, 1978; Miller et al, 1986; Richards, 1991; Titheridge, 1995; Igi et al, 1999), vertical plasma drifts in the equatorial F2-layer (Hari and Murthy, 1995; Ramesh and Sastri, 1995; Batista et al, 1996), neutral composition and winds (Richards and Wilkinson, 1998; Wright and Conkright, 2001)
The Tex∗ S product demonstrates a sort of invariant in the inverse problem considered, large MSIS-86 values of S should result in lower Tex values in accordance with their conclusion
Summary
The idea of using ionosphere plasma parameter observations to obtain various aeronomic parameters has been implemented and used since the beginning of ionospheric research. Much valuable and interesting information on thermospheric winds, temperature and neutral composition has been obtained from ISR data analyses (e.g., Alcaydé et al, 1974, 1982; Babcook and Evans, 1979; Evans et al, 1979; Oliver, 1979, 1990; Alcaydé and Fontanari, 1986; Burnside et al, 1988, 1991; Winser et al, 1988; Blelly et al, 1992; Buonsanto et al, 1992; Aruliah et al, 1997; Lathuillère et al, 1997; Buonsanto and Pohlman, 1998; Schoendorf and Oliver, 1998; Witasse et al, 1998; Buonsanto and Witasse, 1999; Litvin et al, 2000). The main approaches are based on the use of the energy equation for O+ ions to find atomic oxygen concentration and neutral temperature at the F2-region heights and on the momentum equation for O+ ions to retrieve meridional thermospheric winds
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