Halogens and the chemistry of the free troposphere D. J. Lary 1Global Modelling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA 2GEST at the University of Maryland Baltimore County, Baltimore, MD, USA
Abstract. The role of halogens in both the marine boundary layer and the stratosphere
has long been recognized, while their role in the free troposphere is often
not considered in global chemical models. However, a careful examination of
free-tropospheric chemistry constrained by observations using a full chemical
data assimilation system shows that halogens do play a significant role in
the free troposphere. In particular, the chlorine initiation of methane
oxidation in the free troposphere can contribute more than 10%, and in some
regions up to 50%, of the total rate of initiation. The initiation of
methane oxidation by chlorine is particularly important below the polar
vortex and in northern mid-latitudes. Likewise, the hydrolysis of
alone can contribute more than 35% of the
production rate in the free-troposphere.
Citation: Lary, D. J.: Halogens and the chemistry of the free troposphere, Atmos. Chem. Phys., 5, 227-237, doi:10.5194/acp-5-227-2005, 2005.