An estimate of the flux of stratospheric reactive nitrogen and ozone into the troposphere

The globally averaged net downward annual fluxes of reactive nitrogen (NOy) and O-3 from the stratosphere are estimated using observed correlations of N2O with NOy and O-3. The linearity of the observed correlations in the lower stratosphere allows the downward fluxes of NOy and O-3 to be related to the upward flux of N2O. The upward flux of N2O can be calculated from a mass balance and stratospheric photochemistry. In this way, the complicated photochemistry and transport of NOy and O-3 can be bounded by a much simpler calculation involving N2O. The estimated NOy net flux of 0.45 Tg (N) yr(-1) ( range 0.23-0.73) is slightly less than previous estimates, but within the range of uncertainty. Precipitation of NOy from the Antarctic winter stratosphere may be a significant fraction of the annual global flux out of the lower stratosphere. The global budget for stratospheric NOy shows that an N2O lifetime greater than 160 years is inconsistent with extensive mass flow through the Antarctic winter vortex. The estimated O-3 flux of 3.5x10(10) molecules cm(-2) s(-1) (range 1.5-6.8) agrees well with previous estimates using completely independent techniques.