Total ozone increase over North America during the 1960's

Abstract

Analysis of total ozone data from ten North American stations indicates that an ozone increase occurred east of the Rocky Mountains during the 1960's. Calculated rates of ozone increase vary between 2.0 and 8.8% per decade, with a mean of 5.0% per decade for the ten stations. An investigation of the calibration histories of several of the Dobson ozone spectrophotometers with which observations were made suggests that the observed increase in ozone is real and not an artifact caused by long-term drift in instrument calibrations. A brief description of the United States Dobson spectrophotometer program is also presented with emphasis on observational, data reduction, and calibration techniques. Included in the presentation are mean monthly, seasonal, and annual total ozone isopleths for North America for 1961 to 1970.