An automated method for preparing and calibrating electrochemical concentration cell (ECC) ozonesondes

Abstract

In contrast to the legacy manual method used to prepare, condition, and calibrate the electrochemical concentration cell (ECC) ozonesonde, an automated digital calibration bench similar to one developed by MeteoSwiss at Payerne, Switzerland, was established at NASA's Wallops Flight Facility and provides reference measurements of the same ozone partial pressure as measured by the ECC. The purpose of an automated system is to condition and calibrate ECCs before launching on a balloon. Operation of the digital calibration bench is simple and real-time graphs and summaries are available to the operator; all information is archived. The parameters of interest include ozone partial pressure, airflow, temperature, background current, response, and time (real and elapsed). ECCs, prepared with 1.0 % solution of potassium iodide (KI) and full buffer, show increasing partial pressure values when compared to the reference as partial pressures increase. Differences of approximately 5-6 % are noted at 20.0 mPa. Additional tests with different concentrations revealed the Science Pump Corp. (SPC) 6A ECC with 0.5 % KI solution and one-half buffer agreed closer to the reference than the 1.0 % cells. The information gained from the automated system allows a compilation of ECC characteristics, as well as calibrations. The digital calibration bench is recommended for ECC studies as it conserves resources.