In-situ comparison of the NOy instruments flown in MOZAIC and SPURT

[摘要] Two aircraft instruments for the measurement of total odd nitrogen(NO_y) were compared side by side aboard a Learjet A35 in April 2003during a campaign of the AFO2000 project SPURT (Spurengastransport in derTropopausenregion). The instruments albeit employing the same measurementprinciple (gold converter and chemiluminescence) had different inletconfigurations. The ECO-Physics instrument operated by ETH-Zürich inSPURT had the gold converter mounted outside the aircraft, whereas theinstrument operated by FZ-Jülich in the European project MOZAIC III(Measurements of ozone, water vapour, carbon monoxide and nitrogen oxidesaboard Airbus A340 in-service aircraft) employed a Rosemount probe with 80 cmof FEP-tubing connecting the inlet to the gold converter. The NO_yconcentrations during the flight ranged between 0.3 and 3 ppb. The two datasets were compared in a blind fashion and each team followed its normaloperating procedures. On average, the measurements agreed within 7%,i.e. within the combined uncertainty of the two instruments. This puts anupper limit on potential losses of HNO₃ in the Rosemount inlet of theMOZAIC instrument. Larger transient deviations were observed during periodsafter calibrations and when the aircraft entered the stratosphere. The timelag of the MOZAIC instrument observed in these instances is in accordancewith the time constant of the MOZAIC inlet line determined in the laboratoryfor HNO₃.

[学科分类] 大气科学