Global sensitivity of aviation NOx effects to the HNO3-forming channel of the HO2 + NO reaction 1Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
15 Mar 2013
2Johannes-Gutenberg-Universität, Institut für Physik der Atmosphäre, Mainz, Germany
Received: 28 June 2012 – Published in Atmos. Chem. Phys. Discuss.: 17 September 2012 Abstract. The impact of a recently proposed HNO3-forming channel of the HO2
+ NO reaction on atmospheric ozone, methane and their precursors is
assessed with the aim to investigate its effects on aviation NOx
induced radiative forcing.
Revised: 17 January 2013 – Accepted: 25 February 2013 – Published: 15 March 2013
The first part of the study addresses the differences in stratospheric and
tropospheric HOx-NOx chemistry in general, by comparing a global
climate simulation without the above reaction to two simulations with
different rate coefficient parameterizations for HO2 + NO →
HNO3. A possible enhancement of the reaction by humidity, as
found by a laboratory study, particularly reduces the oxidation capacity of
the atmosphere, increasing methane lifetime significantly. Since methane
lifetime is an important parameter for determining global methane budgets,
this might affect estimates of the anthropogenic greenhouse effect.
In the second part aviation NOx effects are isolated independently for
each of the three above simulations. Warming and cooling effects of aircraft
NOx emissions are both enhanced when considering the HNO3-forming
channel, but the sum is shifted towards negative radiative forcing.
Uncertainties associated with the inclusion of the HO2 + NO →
HNO3 reaction and with its corresponding rate coefficient propagate a
considerable additional uncertainty on estimates of the climate impact of
aviation and on NOx-related mitigation strategies.
Citation: Gottschaldt, K., Voigt, C., Jöckel, P., Righi, M., Deckert, R., and Dietmüller, S.: Global sensitivity of aviation NOx effects to the HNO3-forming channel of the HO2 + NO reaction, Atmos. Chem. Phys., 13, 3003-3025, doi:10.5194/acp-13-3003-2013, 2013.