Effects of mixed scatter on SuperDARN convection maps

The SuperDARN radars map high-latitude ionospheric plasma drift velocities by measuring the Doppler frequency shift of HF signals scattered by decameter electron density irregularities. In many cases the ionospheric returns are contaminated by strong scatter from the ground or sea surface. In this paper we develop and test a two-component fitting algorithm to separate ionospheric and surface scatter components. Application of the technique to sample data reveals that mixed scatter may considerably distort ionospheric convection patterns derived from the radar data and can cause underestimation of the plasma drift velocity.