Full field-of-view imaging and multistatic operations for SuperDARN
Borealis radars
Abstract
Super Dual Auroral Radar Network (SuperDARN) consists of more than 30
monostatic high-frequency (HF, 10-18~MHz) radars which
utilise signals scattered from decameter-scale ionospheric
irregularities for studying dynamic processes in the ionosphere. By
combining line-of-sight velocity measurements of ionospheric scatter
echoes from radars with overlapping fields of view, SuperDARN provides
maps of ionospheric plasma drift velocity over mid and high latitudes.
The conventional SuperDARN radars consecutively scan through sixteen
beam directions with dwelling time of 3.5 s/beam, which places a lower
limit of one minute to sample the entire field of view. In this work we
remove this limitation by utilizing advanced capabilities of the
recently developed Borealis digital SuperDARN radar system. Combining a
wide transmission beam with multiple narrow reception beams allows us to
sample all conventional beam directions simultaneously and to increase
the sampling rate of the entire field of view by up to sixteen times
without noticeable deterioration of the data quality. The wide-beam
emission also enabled the implementation of multistatic operations,
where ionospheric scatter signals from one radar are received by other
radars with overlapping viewing areas. These novel operations required
the development of a new model to determine the geographic location of
the source of the multistatic radar echoes. Our preliminary studies
showed that, in comparison with the conventional monostatic operations,
the multistatic operations provide a significant increase in geographic
coverage, in some cases nearly doubling it. The multistatic data also
provide additional velocity vector components increasing the likelihood
of reconstructing full plasma drift velocity vectors.