AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
How does a 10 fold Pulse Increase of Aircraft-Related NOx Impact Global Concentrations of O3 and Secondary Organic Aerosol (SOA)?
NIMA AFSHAR-MOHAJER, Barron Henderson, University of Florida
Abstract Number: 420 Working Group: Effects of NOx and SO2 on BVOC Oxidation and Organic Aerosol Formation
Abstract Aircraft-related industries are fast growing due to their advantages over the other transportation routes and to fulfill the global needs in developing the complicated network of the international relationships. The global fleet of aircrafts emits a variety of air pollutants all over the world. NOx emissions are one of the most important air pollutants emitting from the aircrafts, as they are contributing in formation ozone as well as partitioning of the organic gases into secondary organic aerosol (SOA). Ten times pulse increase in the total NOx emitted from global aircraft fleet in a certain month relative to the baseline was investigated in this study for the entire year of 2007. Presented by Bey et al. (2001), GEOS-Chem model was modified to introduce pulse additions for two different seasonal cases of winter and summer. Pulses of NOx are immediately evident, and the peak ozone burden increase, as expected, lags by a month. For SOA, the relationship is more complex. Initially, the pulse of aircraft NOx increases secondary organic gases due to the extra reactions between NO and RO2 (the product of the aromatic hydrocarbon reactions with OH). Due to the volatility of the produced secondary organic gases (SOG) and higher consumption rate of HO2, however, the burden of SOA decreases by 4.3 times in the Northern America and Europe. Following the pulse for both summer and winter perturbations, concentrations of SOG and SOA generally decreased by 0.016 ppt and returned to normal after almost 6 months. In areas close to industrial units in the northern Far East, SOG and SOA concentrations actually increased for up to 2-3 months following the pulse. The reason for observing positive ∆SOG and ∆SOA values close to the earth surface over the northern hemisphere was having a greater reactions between aromatic hydrocarbons and HO2 compared to the baseline. Understanding the magnitude and duration of perturbations helps use to understand the natural modes of atmospheric chemistry and the inter-relationship of aircraft emissions and biogenic volatile organic compounds.