Using delay doppler processing to separate stratigraphic and basal ice at Dome A, Antarctica

Internal reflecting horizons (IRH) seen in ice penetrating radar data are key markers of ice sheet mass balance and strain [1].  Additional units lacking horizons, but sometimes with diffuse echoes, are also seen at depth in the ice sheet. IRH are characterized by a specular radar response at VHF frequencies. Existing approaches for broadly characterizing IRH [ILCI, 2] focus on their appearance in time delay, but do not exploit azimuth information. In the along track direction, azimuth information can be extracted from delay doppler processing [3,4], and used to constrain roughness and geometric information about the subsurface [4,5,6,7].  We find that basal ice can be cleanly separated from stratigraphic on the basis of its delay doppler appearance in 60 MHz MARFA data.

Here we present an automatically generated volume of basal and stratigraphic ice for the Dome A region using NSF Center for Oldest Ice Exploration (COLDEX) radar data collected in between 2022 and 2024, based on delay doppler thresholding, and compare this to manual interpretation of COLDEX radargrams [8].  We also demonstrate the approach on selected other regions of Antarctica, and examine how as a quality estimate this delay doppler approach complements the ILCI approach.

 

1. Bingham, Bodart, Cavitte, Chung, Sanderson, Sutter et al., in review; doi:10.5194/egusphere-2024-2593

2. Karlsson et al, 2014, doi:10.1016/j.epsl.2012.04.034

3. Raney, 1998; doi:10.1109/36.718861

4. Peters et al., 2005; doi:10.1029/2004JB003222

5. Schroeder et al. 2014; doi:10.1109/LGRS.2014.2337878

6. Castelletti et al., 2019; doi:10.1017/jog.2019.72

7. Arenas-Pingarrón et al., 2023; doi:10.5194/egusphere-egu23-2856

8. Young, Paden et al, 2024; doi:10.18738/T8/J38CO5