A Study of Technique for the Measurement of Total Reactive Nitrogen in the Troposphere

点击翻译按钮获取中文摘要

NO_y is measured by converting it to NO catalytically on the surface of a heated gold tube under the addition of CO. Subsequently this NO is detected with an NO detector as described above.To determine the zero level of NO and NO_y instruments purified gas that doesn't contain NO or NO_y is directed into the reaction chamber instead of the ambient air. It was shown that purified air fulfills therequirements for stable and low zero signal better than purified oxygen and nitrogen.One important criterion for the performance of the NO_y instrument is it's capability to convert reactive nitrogen on the heated gold tube into NO. For the interpretation of the data obtained during a balloonflight in Northern Sweden in January 92 it was crucial to know to which degree NO_y was converted into NO. Measurements in the laboratory have shown that the conversion efficiency was close to 100%.Extensive measurements in the laboratory have been carried out to study the possible influence of condenced water in the sample air. In the free troposphere the temperatures are usually far below 0ﾟC. These low temperatures cause a cooling of the inlet line of the NO_y instrument. The descending aircraft encountered more humid air in the lower troposphere and boundary layer, which then whould condense on the cooled sample line. Considering this effect modifications of the NO_y instrument were made to prevent this interference in future field measurements.