PLASMA TRANSPORT IN THE IONOSPHERE - EISCAT-VHF OBSERVATIONS AND NUMERICAL-MODELS

The understanding of the magnetosphere-ionosphere couplings requires t he concomitant use of experimental facilities and numerical tools. The European Incoherent Scatter radar (EISCAT), able to provide instantan eous vertical profiles of the ionosphere, makes possible the developme nt of data processing methods to get boundary parameters, in particula r the topside downward electron heat flow: this boundary parameter is crucial for the purpose of quantitative modelling of the ionosphere. I t characterises at auroral latitudes the energy transfer from the magn etosphere to the ionosphere and is determinant for the development of fluid numerical models of the ionosphere. This paper presents how with such a boundary condition obtained from the data, the steady-state an d the dynamic behaviour of the ionosphere-from 100 to 3000 km-can be q uantitatively reproduced with a fluid description of the plasma. Coupl ing between atmosphere and ionosphere is included through chemistry an d collisions while the particle and energy transfers from the magnetos phere to the ionosphere are included through ionisation and energy dep osition resulting from electron precipitations.