Methodology:

The raw data was collected by the airborne Synthetic Aperture Radar (SAR) PASIN2. It is 150-MHz coherent pulsed radar, transmitting chirped pulses with linear frequency sweep, with 13 MHz bandwidth and effective pulse repetition frequency 125 Hz. On board of a De Havilland DHC-6 Twin Otter aircraft, in ice-sounding flights the nominal speed is 60 m/s, and the terrain clearance (height above closest surface) is 300 m. PASIN2 has 12 antenna elements: 8 underwing folded-dipoles switching between transmit (TX) and receive (RX) modes, and 4 printed-dipoles being RX-only attached to the fuselage belly. The data processing is performed off-line, consisting of: 1) channel calibration; 2) 2D SAR imaging, based on pulse-compression for range dimension, and back-projection for along-track dimension; 3) Direction of Arrival estimation (DoA) of the remaining across-track angle, based on the non-linear MUSIC (Multiple Signal Classification) algorithm, by using several SAR images from different transmitters or receivers; and 4) 3D-mapping from the three dimensions of range, along-track and across-track angle, by correcting the real depths and across-track distances, regarding the case of incorrectly assumed vertical DoA of a single SAR image. In this dataset are included: the SAR and DoA images from nominal surveying flights above the Recovery Glacier; and calibration data and the measured antenna patterns, from calibration flights above the sea surface near Rothera Research Station.

Data collection:

PASIN2 (Polarimetric Airborne Scientific INstrument, mark 2) radar; Matlab R2020b software. The parameter files used for processing, and a script for generating the plots with antenna patterns, are in the open repository https://github.com/antarctica/calibration-processing-parameters-PASIN2.git.

Data quality:

The amplitude and relative phase of the antenna patterns in transmission (as an array of 4 antennas) and reception (as 12 single and independent antennas), were assessed with calibration flights above the sea surface. The patterns are assumed as invariant along each session, if the antenna configuration remains. Direction of Arrival (DoA) estimation algorithms were evaluated with calibration flights.

The transmitted radar pulses are not calibrated, as parameter drifts are not expected to affect the quality. In the receiver units, during each flight there is a drift in the recording, causing a delay and phase drift in the sampled data, which is corrected when combining the several SAR images to process a single Direction of Arrival (DoA) image.