On the Use of nonmethane hydrocarbons for the Determination of Age Spectra in the Lower Stratosphere

Ehhalt, D. H.; Konopka, P.; Blake, D. R.; Rohrer, F.; Kinnison, D. E.

doi:10.1029/2006JD007686

Journal Article

PreJuSER-57411

On the Use of nonmethane hydrocarbons for the Determination of Age Spectra in the Lower Stratosphere

Ehhalt, D. H.FZJ* ; Rohrer, F.FZJ* ; Blake, D. R. ; Kinnison, D. E. ; Konopka, P.FZJ*

2007
Union Washington, DC

Journal of Geophysical Research 112, D11208 (2007) [10.1029/2006JD007686]

This record in other databases:

Please use a persistent id in citations: http://hdl.handle.net/2128/20421 doi:10.1029/2006JD007686

Abstract: On 9 April 2001, while approaching the West Coast of the North American continent, flight 20 of the NASA TRACE P campaign penetrated deeply into a stratospheric intrusion. From measurements aboard that flight we derive vertical profiles of nonmethane hydrocarbons (NMHCs) and other short-lived trace gases in the lower stratosphere using Dichlorofluoromethane, CF2Cl2, as the altitude scale. All profiles show an exponential decrease, which permits the description of their vertical distribution by a single parameter, the scale height. These scale heights are shown to be related to the respective lifetimes in a unique fashion. Using the approximation of a 1-D diffusive model with a constant eddy diffusion coefficient, K, and assuming constant lifetimes, we establish an analytical solution for this relation. By fitting this theoretical expression to the experimental data we can estimate K and thus obtain an approximate age spectrum of the form given by Hall and Plumb (1994). A much better fit to the experimental scale heights is obtained, when we allow the lifetimes to be height-dependent and calculate the theoretical scale heights numerically from a 1-D model. An optimization also suggests a constant K, but with a value of 0.46 m(2)/s, larger than those obtained from the fit of the analytical solution. The obtained age spectra should be valid for transit times not longer than 300 days.

Keyword(s): J

Classification: