A historical overview is presented of Dobson spectrophotometer total ozone observations made by the U.S.A.'s National Oceanic and Atmospheric Administration (NOAA) since the early 1960s. NOAA's contributions in upgrading the quality of total ozone measurements in the global Dobson instrument network, and in providing `ground truth' to satellite ozone observations, are also briefly described. Because ozone trend estimates to within +/- 1% per decade require highest quality data, a program was initiated in 1992 to reprocess the NOAA data with application to the data of final corrections. Trend results for a number of stations are presented and compared with trends derived from satellite instrument ozone measurements. Ozone variations and the downward trend in global ozone of recent years, including the accelerated ozone decrease that began in 1992 and has continued into 1993, are discussed in light of photochemical and dynamical processes that are potentially capable of altering global ozone abundance. Although the Mount Pinatubo eruption of 1991 is suspected of contributing to the most recent decrease in ozone, the mechanisms responsible for the ozone changes observed more than a year after the eruption remain under investigation.
Walter D. Komhyr,
"USA Dobson spectrophotometer total ozone measurements program: 1962-1992", Proc. SPIE 2047, Atmospheric Ozone, (2 November 1993); doi: 10.1117/12.163466; http://dx.doi.org/10.1117/12.163466