Depleted hole


  • Michael Carlowicz


Despite predictions of a new record, as well as an early, fast-paced start, the ozone hole over Antarctica has not grown as wide or as deep as researchers initially expected (Eos, September 17). According to data gathered by NASA's total ozone mapping spectrometers and by researchers using ground-based instruments, the average size of the Antarctic ozone hole in 1996 was almost as large (21.6 million km2) as it was in the peak year of 1993 (22.1 million km2). But ozone concentrations are higher than they were during the record lows in 1994. Ozone concentrations dropped as low as 111 Dobson units at the center of the hole on October 5, with values below 222 Dobson units measured over a wide area. The record low point value in 1994 was 88 Dobson units.