New Pump Correction for the Brewer–Mast Ozone Sonde: Determination from Experiment and Instrument Intercomparisons

Abstract Pump efficiency of the Brewer–Mast (B–M) ozone sonde deteriorates significantly at altitudes above 22 km (pressures below 50 hPa). The correction currently used as the WMO standard does not sufficiently account for the efficiency decrease. It is based on laboratory measurements made in 1965. The authors have redetermined pump efficiency for the B–M sonde and found that a much higher pump correction is appropriate. The net effect of the new pump correction, after Dobson normalization to integrated ozone, is a substantial increase of ozone values above 28 km (15 hPa) and a small decrease below. At 6 hPa (34–35 km) ozone values need to be increased by 20%. From 22 to 28 km (50–15 hPa) net corrections are smaller than 4%. Below 16 km (100 hPa) ozone values decrease by 5%–7%. Using the new pump correction, agreement of better than 2%–5% is found with lidar, SAGE II, electrochemical concentration cell (ECC) sondes, and HALOE (Halogen Occultation Experiment) for the entire altitude range from 16 to 35 k...