Science Concepts The ionosphere contains a weakly ionized plasma. Although the ionosphere strongly reflects, modifies and absorb radio waves, it is in fact a weakly ionized plasma. Even at peak ionospheric densities the ion to neutral ratio is less than 1%. Traditionally ionospheric studies were based mostly on radio wave probing and earlier studies emphasized the importance of factors from above e.g. solar irradiation, solar wind coupling, through the magnetosphere. The influence of the lower atmosphere through thermospheric chemistry and dynamics was mostly neglected. From recent studies it is clear that the ionosphere is highly dependent on the chemistry and dynamics of the thermosphere and is strongly coupled with regions below including the troposphere (weather). This strong coupling is evidenced by the pressence of the same seasonal variations and longitudinal structure in both the tides and ionospheric densities. Though tides in the upper-atmosphere have previously been found to influence the ionosphere, it is becoming clear that Earth's ionosphere is actually tidally dominated. Last Edited