Co-ordinated studies using imaging riometer and incoherent scatter radar

Abstract

Abstract A 49 beam imaging riometer (IRIS) has been operational at Kilpisjarvi, Finland, since September 1994. One of the main purposes of this installation is joint studies with the EISCAT incoherent scatter radar system, whose transmitters are 83 km from the riometer site. We discuss the scope for investigations using combined EISCAT and IRIS data and illustrate some of these with examples. Emphasis is placed on aspects of the ionospheric D-region and mesosphere, but potential areas of exploitation extend to the E-region, the F-region and the magnetosphere, and include ionospheric modification experiments. The application of IRIS data to help differentiate between spatial and temporal variations in EISCAT measurements is a fundamental strength of such joint studies. In one example of a substorm onset during daylight conditions, the spatial distribution and dynamics of the radio absorption showed a morphology similar to that of visible aurora at substorm onset, including spectral hardening. The IRIS data allowed the dual-beam EISCAT observations to be set in a proper spatial context with respect to the dynamical changes in particle precipitation. A comparison of electric field measurements from EISCAT with the horizontal motions of different types of absorption event revealed no consistent relationship between the two.