Monitoring the tabular icebergs C28A and C28B calved from the Mertz Ice Tongue using radar remote sensing data

Abstract

We analyzed the evolution processes of two tabular icebergs, C28A and C28B, originating from iceberg C28, using continuous multisource radar remote sensing data. The monitoring began during the calving of iceberg C28 from the Mertz Ice Tongue in February 2010 and ended in April 2012. The evolution of the iceberg area was determined from ENVISAT ASAR images, and the freeboard change was derived from CryoSat-2 profiles. Two patterns of iceberg area decreases are observed during iceberg drifting. In austral summer (from October to next March), iceberg area shows a gradual decrease and it is interpreted to represent edge wasting, sidewall melting and wave erosion, the gradual decrease of the area of C28A occurred at rates between 8.1 km2/month and 16.5 km2/month. In austral winter (from April to September), iceberg area has several discrete decreases (sudden drop) while it remained constant for most of the time, and it is interpreted to be large rift calving primarily caused by ocean swell and basal melting. Calving area of the two studied icebergs is observed to be greater in the winter. The freeboard decreased at different rates at different locations on the same iceberg (between −0.02 ± 0.22 and −0.82 ± 0.28 m/month for C28A and C28B), suggesting a laterally inhomogeneous melting of icebergs. The average rate of change of the C28B freeboard during its 22-month grounding period was −0.03 ± 0.01 m/month, which is considerably smaller than the −0.76 ± 0.23 m/month observed when it was freely drifting in the ocean. The cold-water regime surrounding the iceberg can help the iceberg maintain a stable state. This study reveals the potential use of radar remote sensing when monitoring Antarctic icebergs.