| Summary: | The subtropical and polar upper troposphere fronts and the polar vortex serve as the boundaries to divide the Northern Hemisphere into four meteorological regimes. These regimes are defined as (1) the arctic regime – within the polar vortex, (2) the polar regime – between the polar front and the polar vortex, or when the latter is not present, the pole, (3) the midlatitude regime – between the subtropical and polar fronts, and (4) the tropical regime – between the equator and the subtropical front. Data from the Halogen Occultation Experiment (HALOE) and the Stratospheric Aerosol and Gas Experiment II (SAGE II) were used to show that within each meteorological regime, ozone and water profiles are characterized by unique ozonepause and hygropause heights. Daily measurements and seven-year (1997–2003) monthly climatologies showed that, within each meteorological regime, both constituents exhibited distinct profile shapes from the tropopause up to approximately 20 km. This distinction was most pronounced in the winter and spring months, and weak in the summer and fall. Despite differences in retrieval techniques and sampling between the SAGE and HALOE instruments, the seven-year monthly climatologies calculated for each regime agreed well for both species below ~22 km. Given that profiles of ozone and water vapor exhibit unique profiles shapes within each regime in the UTLS, trends in this region will therefore be the result of both changes within each meteorological regime, and changes in the relative contribution of each regime to a given zonal band over time.
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