Marco Antonio Milla Bravo: Institute Colloquium on January 26th

Marco Antonio Milla Bravo will talk about: "Perpendicular to B incoherent scatter radar studies at the magnetic equatorr"

The incoherent scatter radar (ISR) spectrum measured with antenna beams pointing perpendicular to the geomagnetic field (B) is very narrow, much narrower than the spectrum measured away from the perpendicular direction. This particular characteristic of the incoherent scatter spectrum has been studied by different authors over the years in order to develop an accurate spectral model for ionospheric observations and also to estimate plasma parameters. For instance, using the 50 MHz incoherent scatter radar at the Jicamarca Radio Observatory, it is possible to estimate very accurate vertical F-region plasma drifts from perpendicular to B ISR measurements. More recently, new incoherent scatter radar observations have been conducted with the AMISR-14 radar also at Jicamarca. The AMISR-14 system operates at 445 MHz and can deliver pulses at a nominal peak power of 224 kW. Applying a standard long pulse configuration, F-region spectral measurements were obtained. When pointing perpendicular to B, the spectrum shows a relatively narrow shape with a spectral width in the order of a few kHz. More interesting, spectral peaks at frequencies around the lower hybrid oscillation were also detected. In this presentation, we will describe some of the experiments that have been conducted at Jicamarca to obtain the perpendicular to B incoherent scatter observations. The efforts to model the spectral measurements applying a Coulomb collision incoherent scatter spectral approach will be also described.