Three-dimensional simulation of N2O transport and Antarctic vortex evolution. Ph.D. Thesis
Thesis/Dissertation
·
OSTI ID:237293
This study focuses on three areas: the structure of the stratospheric antarctic vortex and its evolution; the transport of N2O and dynamical forces that dominate these processes; and the climatology of the N2O mixing ratio distribution and its driving factors. A three-dimensional spectral chemical transport model was employed to simulate N2O transport and study the driving forces that affect the processes. The dynamical driving fields are from the UKMO four-dimensional assimilated data set. UARS CLAES N2O mixing ratios are used for the N2O initial conditions. Model results show that distribution and transport closely resemble the CLAES measurements. Diagnostic study and model simulation results reveal that large-scale Eulerian mean vertical motion fields are upward inside the vortex, the mean residual circulation vertical velocity is downward. In the meridional transport of N2O, eddy transport is the chief process. However, the residual circulation transport dominates the long term vertical mixing. The bulge of the elevated N2O mixing ratio in the tropical stratosphere is determined by the uplifting of mass by the residual circulation. The downward transport inside the vortex can exceed 2 ppb/day in the winter hemisphere. The climatological distribution of the N2O mixing ratio follows the seasonal variations of the solar radiation. The bulge of the elevated N2O shifts toward the summer hemisphere by up to 15 degrees in latitude. The slopes of the N2O mixing ratios are sharper in the winter hemisphere and the surf zone is well defined in the middle latitudes on the zonal mean plots.
- Research Organization:
- Georgia Inst. of Tech., Atlanta, GA (United States)
- OSTI ID:
- 237293
- Report Number(s):
- N--96-22460; NIPS--96-33216
- Country of Publication:
- United States
- Language:
- English
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