A SuperDARN HF radar pair (Saskatoon-Kapuskasing) has been used to measure Doppler spectra of backscatter from the dayside F-layer. Normally the spectra are single-peaked, but a small fraction exhibit a double-peaked (D-P) signature. On the 2D convection maps, these D-P spectra occur in range cells located poleward of the convection reversal. A comparison with DMSP SSJ/4 particle data measurements and their mapping to magnetospheric boundaries shows that the D-P spectra are concentrated just equatorward of the magnetopause, in regions of spatially/temporally structured soft electron precipitation (about 300 eV) where the highly variable flux can reach 2--5 ergs/cm2/s. The D-P spectra are most easily explained in terms of scattering from small-scale vortices of size less than the radar resolution of 45 km. The D-P spectral measurements are illustrated by SuperDARN and DMSP data for a dayside event on Feb. 20, 1995, when northward IMF conditions prevailed. We conclude that HF radar D-P observations can be used to map in real time the dayside 2D ionospheric footprint of the outer LLBL. ¿ 1997 American Geophysical Union