Effects of biogenic nitrate chemistry on the NOx lifetime in remote continental regions 1Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
17 Dec 2012
2Department of Earth and Planetary Sciences, University of California Berkeley, Berkeley, CA, USA
Received: 21 June 2012 – Published in Atmos. Chem. Phys. Discuss.: 17 August 2012 Abstract. We present an analysis of the NOx budget in conditions of low
NOx (NOx = NO + NO2) and high biogenic
volatile organic compound (BVOC) concentrations that are characteristic of
most continental boundary layers. Using a steady-state model, we show that
below 500 pptv of NOx, the NOx lifetime is extremely
sensitive to organic nitrate (RONO2) formation rates. We find that even
for RONO2 formation values that are an order of magnitude smaller than is
typical for continental conditions significant reductions in NOx
lifetime, and consequently ozone production efficiency, are caused by nitrate
forming reactions. Comparison of the steady-state box model to a 3-D chemical
transport model (CTM) confirms that the concepts illustrated by the simpler
model are a useful approximation of predictions provided by the full CTM.
This implies that the regional and global budgets of NOx, OH, and
ozone will be sensitive to assumptions regarding organic nitrate chemistry.
Changes in the budgets of these species affect the representation of
processes important to air quality and climate. Consequently, CTMs must
include an accurate representation of organic nitrate chemistry in order to
provide accurate assessments of past, present, and future air quality and
climate. These findings suggest the need for further experimental constraints on
the formation and fate of biogenic RONO2.
Revised: 04 December 2012 – Accepted: 07 December 2012 – Published: 17 December 2012
Citation: Browne, E. C. and Cohen, R. C.: Effects of biogenic nitrate chemistry on the NOx lifetime in remote continental regions, Atmos. Chem. Phys., 12, 11917-11932, doi:10.5194/acp-12-11917-2012, 2012.