Ozone sonde cell current measurements and implications for observations of near-zero ozone concentrations in the tropical upper troposphere
Abstract
Abstract. Laboratory measurements of the Electrochemical Concentration Cell (ECC) ozone sonde cell current using ozone free air as well as defined amounts of ozone reveal that background current measurements during sonde preparation are neither constant as a function of time, nor constant as a function of ozone concentration. Using these background currents in the processing of ECC data may lead to operator dependent uncertainties and may frequently lead to artificially low ozone concentrations in the upper tropical troposphere. Based on these laboratory measurements an improved cell current to partial pressure conversion is proposed, which removes operator dependent variability in the background reading, and possible artifacts in this measurement. Data from the Central Equatorial Pacific Experiment (CEPEX) have been reprocessed using the improved background treatment based on these laboratory measurements. In the reprocessed data set near-zero ozone events no longer occur. At Samoa, Fiji, Tahiti, and San Cristóbal, nearly all near-zero ozone concentrations occur in soundings with larger background currents. To a large extent, these events are no longer observed in the reprocessed data set using the improved background treatment.
Publisher
Copernicus GmbH
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