Electron density in the cusp ionosphere: when the ESR confirms TRANSCAR predictions

Pitout, F.1 and Blelly, P.-L.2

1 LPG, Grenoble, France
2 LPCE, Orléans, France

The ionosphere beneath the polar cusp has been extendedly studied until now in order to understand the processes leading to IS radar observations. In a previous work, Pitout and Blelly (2003), using the TRANSCAR ionospheric model, predicted the response of the ionospheric plasma parameters, especially focusing on the electron density, in response to intense magnetosheath particles precipitation and strong convection electric field. One of their conclusions was that the electron density in the cusp is primarily ruled by its initial electron content, i.e. by the origin of the flux tubes. We present ESR data that clearly show this trend. Moreover, we have run a series of ESR experiments to verify another prediction: in certain conditions, the electron density should decrease almost immediately after the opening of the field line. The ESR 32m-antenna was used to scan the dayside polar ionosphere alternatively in azimuth and elevation in order to have 2D views of the ionosphere in two planes. Again, our observational results agree well with the simulations.