A comparison of Ne (h) model profiles with ground-based and topside sounder observations

Abstract

Monthly median empirical models IRI-95 and NeUoG were compared with incoherent scatter EISCAT and Millstone Hill observations as well as with El Arenosillo Digisonde N e (h) bottomside profiles. A comparison was made for various seasons, levels of solar activity, daytime and night-time hours. The results on the topside comparison: 1) the IRI-95 model systematically and strongly overestimates the Ne (h) effective scale height both for daytime and night-time periods especially during maximum and middle solar activity both at EISCAT and Millstone Hill; 2) the NeUoG model on the contrary systematically underestimates the scale height at all levels of solar activity. But the NeUoG model provides much better overall agreement with SD being less by a factor of 1.5-1.7 in comparison with the IRI-95 model results. The results on the bottom-side comparison: 1) the IRI-95 accuracy is different for daytime and night-time hours, being much worse for the night-time; 2) the NeUoG model similar to IRI-95 demonstrates much worse accuracy for the night-time hours; 3) the NeUoG model demonstrates no advantages over the IRI-95 model in the bottomside N e (h) description. A new simple TopN e model for the N e (h) topside distribution based on the EISCAT and Millstone Hill observations is proposed. The model is supposed to be normalized by the observed hmF 2 and NmF 2 values and is valid below a 600 km height. The TopN e model provides good approximation accuracy over EISCAT and Millstone Hill observations. A comparison with the independent Intercosmos-19 topside sounder observations is given.