Polarimetric Airborne Scientific INstrument, mark 2 (PASIN2) is a 150 MHz coherent
pulsed radar with the purpose of deep ice sounding for bedrock, subglacial channels and
ice‐water interface detection in Antarctica. It is designed and operated by the British
Antarctic Survey from 2014. With multiple antennas, oriented along and across‐track, for
transmission and reception, it enables polarimetric 3D estimation of the ice base with a
single pass, reducing the gridding density of the survey paths. The off‐line data processing
stream consists of channel calibration; 2D synthetic aperture radar (SAR) imaging based
on back‐projection, for along‐track and range dimensions; and finally, a direction of
arrival estimation (DoA) of the remaining across‐track angle, by modifying the non‐linear
MUSIC algorithm. Calibration flights, during the Antarctic Summer campaigns in 16/17
and 19/20 seasons, assessed and validated the instrument and processing performances.
Imaging flights over ice streams and ice shelves close to grounding lines demonstrate the
3D sensing capabilities. By resolving directional ambiguities and accounting for reflector
across‐track location, the true ice thickness and bed elevation are obtained, thereby
removing the error of the usual assumption of vertical DoA, that greatly influence the
output of flow models of ice dynamics