Stratospheric Ozone Transport due to Transient Large Amplitude Planetary Waves

[摘要] The role of a temporary amplification of planetary waves in transport of the stratospheric ozone in mid-winter is studied with the use of a semi-spectral hemispheric primitive equation model. The results of a simulation involving zonal wavenumber 1 are presented.The wave forcing at the lower boundary (5km) is turned on at day 0, reaches the maximum at day 5, and then decays after day 20 and to become zero at day 25.The three-dimensional Lagrangian motions are investigated by tracing a large number of marked particles placed along latitude circles at the initial time. The Lagrangian motions in the middle and lower stratosphere are irreversible owing to the dissipations and the lower latitude critical surface. The particles in higher latitudes are found to return to the initial latitude after the wave has damped except for permanent downward displacements. In contrast, a material line consisting of air parcels at lower latitudes is cut off somewhere in the course of time evolution and some particles migrate poleward largely, and finally the members are widely scattered in both the meridional and horizontal planes.The ozone continuity equation is integrated for two types of ozone models: the Chapman and the inert models. When the planetary wave develops, large ozone wave is induced in middle latitudes followed by the total ozone enhancement in high latitudes and a little decrease in the tropical region. The latitudinal pattern of the tonal mean column ozone at the active stage of the planetary wave is almost maintained even after the wave has disappeared when the ozone distribution becomes axi-symmetric again. This net ozone change is largely responsible for the observed spring ozone maxima.The divergence (convergence) of the photochemically induced ozone eddy flux is almost cancelled by the mean photochemical source in the mid-latitude transition region, in the results the Chapman cycle acts only as diffusion.

[学科分类] 大气科学