Simulation of stratospheric N2O in the NCAR CCM2: Comparison with CLAES data and global budget analyses

Global variability and budgets of stratospheric nitrous oxide (N2O) are studied using output from a stratospheric version of the National Center for Atmospheric Research Climate Model (CCM2). The model extends over 0-80 km, incorporating an N2O-like tracer with tropospheric source and upper-stratospheric photochemical sink, the latter parameterized using linear damping rates obtained from detailed two-dimensional model calculations. Results from the model over several seasonal cycles are compared with observations of N2O from the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument on the Upper Atmosphere Research Satellite (UARS). The model produces N2O structure and variability that is in reasonable agreement with the observations. Global budgets of stratospheric N2O are furthermore analyzed using model output, based on the transformed Eulerian-mean, zonal-mean framework. These budgets are used to quantify the importance of planetary wave constituent transport in the stratosphere, for both slow seasonal variations and fast planetary wave events. These results demonstrate that such wave fluxes act to form and sharpen the strong subtropical N2O gradients observed in satellite measurements.