Data on bottom water in Prydz Bay, Antarctica, revised



We report on salinity biases in conductivity-temperature-depth (CTD) data collected offshore Prydz Bay that affect conclusions about possible bottom water formation. The role of the Prydz Bay region (68–81°E) in bottom water production around Antarctica is an important unresolved issue [Smith and Treguer, 1994; Nunes Vaz and Lennon, 1996; Whitworth et al., 1998]. Wong, Bindoff, and Forbes [1998] identified a new, dense water type over the abyssal plain northwest of the Prydz Bay Channel at ˜72.5°E. Its spatial pattern was such that the highest sea floor salinities, ˜0.03 psu above historical measurements, were observed nearest the channel and decreased westward, away from Prydz Bay

Examination of the calibrated CTD data bottle data analyzed in Wong et al. [1998] shows a systematic bias in salinities off the continental shelf, most strongly in the stations to the west of Prydz Bay. The bias appears directly attributable to an undetected deterioration in conductivity cell performance toward the end of the observation program. The change in cell behavior is consistent with a cracked conductivity cell. This deterioration introduced an artificial curvature into the salinity profiles at depths exceeding 2000 m and a wider spread of the bottom salinity values to the west and north of Prydz Bay.