The Doppler velocity (top), backscatter power (middle), and spectral width (bottom) from the Hankasalmi HF radar at 8:30 UT (left column) and 8:36 UT (right column). The ground backscatter, which is characterized by low Doppler velocity and low spectral width, is displayed in grey. The ionospheric convection pattern and fitted drift velocities are also overlayed. The GPS IPPs for the same time periods as Figure 3b are shown as black lines (GPS phase scintillation strengths are not indicated here for clarity). The black and pink lines show the track of NOAA-16 and NOAA-17, respectively. The OCBs identified from both spacecraft are annotated by black and pink arrows and they agree very well, see text and Figure 6 for more detail.