In 1995, that instrument was no longer working, but balloon-borne instruments measured near-record values below 100 Dobson units
in the atmosphere above the South Pole.
He and his colleagues recorded a low of 100 Dobson units
of ozone on Sept.
6, the balloon ozone sensors detected only 90 Dobson units
of ozone, a reading corroborated by a ground-based spectrometer.
In contrast to the satellite data -- which indicate that this year's lowest ozone concentration was roughly 126 Dobson units
-- balloon measurements made on Oct.
6, the concentration of ozone over parts of Antarctica dropped to 110 Dobson units
, beating a record of 121 Dobson units
, set in 1987, says NASA's Arlin Krueger.
Balloon-borne sensors measured ozone values as low as 195 Dobson units
during the second week of September, 1 week earlier than usual, says Samuel J.
Satellite measurements show that the ozone concentration in the Antarctic stratosphere -- 12 to 50 kilometers up -- reached 125 Dobson units
TOMS data show that the minimum ozone level over Antarctica plummeted from 200 Dobson units
in mid-August to 133 Dobson units
In that slab we've gone from 50 Dobson units
[of ozone] at the end of August to something like 5 Dobson units
," Hofmann says.