TY JOUR TI Electron density in the polar F region ionosphere during solar minimum: modeling, radar and ionosonde observations KW Polarš¹region ionosphere KW numerical modeling KW plasma density KW EISCAT radar KW SGOionosonde JO Russian Journal of Earth Sciences AU Lukianova, R.. AU Kozlovsky, A.. PY 2020 IS 20 PB Geophysical Center of the Russian Academy of Sciences