Wednesday, 10 January 2018
Exhibit Hall 3 (ACC) (Austin, Texas)
N2O5 is potentially an important reservoir of NOx (NOx = NO + NO2) in the remote atmosphere. However, to date most measurements of N2O5 have been performed in polluted atmospheres at lower altitudes. During the ATom-2 deployment a thermal decomposition-chemical ionization mass spectrometer (TD-CIMS) using iodide as a reagent ion was deployed to measure PAN. This also gave the opportunity to measure the sum of NO3 and N2O5, which during the day is expected to be dominated by N2O5. Preliminary analysis and calibrations indicate that N2O5 was less than 20 pptv for almost all flight conditions. However, an interference to this measurement at high ozone levels was observed in stratospheric air. This degraded the detection limit of this method at high altitude. Here we will present the observed distributions of N2O5 and compare them to those predicted by a global model. We will also present our analysis of the mechanism for the ozone interference to the iodide CIMS detection of N2O5 and other species.
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