Self-consistent modelling of the daytime electron density profile in the ionospheric F region

• Published in: Annales Geophysicae
• Main Authors: Mikhailov, A., Schlegel, K.
• Format: Text
• Language: English
• Published: 2018
• Subjects: EISCAT
• Online Access: https://doi.org/10.1007/s00585-997-0314-9; https://angeo.copernicus.org/articles/15/314/1997/

A theoretical self-consistent method for the description of daytime N e (h) profiles in the ionospheric F region measured by EISCAT is proposed. It is based on the use of a theoretical F-region model and measured electron density, N e (h) , electron, T e (h) , and ion temperature, T i (h) , and field-aligned plasma drift V l (h) profiles. The method describes the observed N e (h) profile with high accuracy for quiet and disturbed conditions. Two versions of the method are considered: in the first the exospheric temperature T ex is derived from a procedure minimizing [log( N e (h) obs / N e (h) cal ] 2 , in the second T ex is deduced from the ion energy conservation in the F region. The method allows us to infer from the incoherent-scatter observations: concentrations of atomic oxygen, [O], molecular oxygen, [O 2 ], molecular nitrogen, [N 2 ] the vertical plasma drift, W , the exospheric temperature. T ex , and the shape parameter S in the neutral temperature profile. The ratio ([O + ]/ N e ) calculated by the theoretical model is used to correct T e (h), T i (h) and N e (h) profiles routinely measured with EISCAT which are known to depend strongly on the actual applied ion-composition model. Such a correction is especially important for geomagnetically disturbed periods when the F region is strongly enriched with molecular ions. We conclude that four of the six thermospheric parameters, namely [O], [N 2 ], W and T ex can be confidently inferred from the EISCAT observations, while the other two derived parameters, [O 2 ] ans S are less reliable. The method can be used for the analysis of long-term (seasonal, solar cycle) as well as for day-to-day variations of the thermospheric parameters and the F-region ion composition using daytime incoherent-scatter observations.