Fronts and Frontogenesis as Revealed by High Time Resolution Data

摘要

A cold front of moderate intensity was investigated using upper air soundings taken every three hours. The front was found to have a complex structure. The front showed up clearly on analyses of surface weather, but isentropic cross sections showed this front to be quite shallow and weak. Hyperbaroclinic zones were found in the middle and upper troposphere above the surface feature, and these zones were of much greater intensity than the surface front. The multiple structures of these zones were observed on all cross sections. These fronts were of greater intensity and showed more activity near the trough axis than to the east of the trough. The fronts were observed to build to as low as 800 mb by incorporation of pre-existing stable layers. Consideration of the distribution of potential vorticity indicates that the air in the upper portion of these fronts is of stratospheric origin.