Intercomparison of total ozone measured at low sun angles by the Brewer and Dobson spectrophotometers at Scott Base, Antarctica

The total ozone measurements made at Scott Base (78°S, 167°E) with Dobson spectrophotometer #17 and Brewer spectrophotometer #50 during the 1991 Antarctic ozone hole season are compared. Due to the high latitude of Scott Base, these measurements have been made using low‐sun measurement techniques, which are considered to be less reliable and less accurate. The differences between the quasi‐simultaneous total ozone measurements, and the mean daily total ozone values, from Dobson instrument 17 and Brewer instrument 50 are generally between ±5%. The Dobson‐Brewer differences can, on occasions, be as great as 10% for measurements made at airmass values between 5 and 6. The Dobson and Brewer ozone data are generally within ±5% of the Total Ozone Mapping Spectrometer (TOMS) value.