Stratospheric influences on sea-level cyclogenesis and anticyclogenesis

Investigations of several cases of sea-level cyclogenesis and anticyclogenesis reveal that the troposphere-stratosphere air column warms over each intensifying cyclone and cools over each intensifying anticyclone. The warming over each cyclone is caused by vertically integrated, horizontal warm-air advection and by adiabatic warming in the stratosphere. The stratospheric adiabatic warming is due to gentle descent, forced by upper tropospheric cyclonic vorticity advection, coupled with very stable air. The column warming over each intensifying cyclone is opposed, but not overwhelmed, by vertically integrated adiabatic cooling. This cooling is associated with ascent forced by the warm-air advection throughout the column and by tropospheric ascent forced by cyclonic vorticity advection.

Conversely, the cooling over each intensifying anticyclone is caused by vertically integrated, horizontal cold-air advection and by adiabatic cooling in the stratosphere. The stratospheric adiabatic cooling is due to gentle ascent, forced by upper tropospheric anticyclonic vorticity advection, coupled with very stable air. The column cooling over each intensifying anticyclone is opposed, but not overwhelmed, by vertically integrated adiabatic warming. This warming is associated with descent forced by the cold-air advection throughout the column and by tropospheric descent forced by anticyclonic vorticity advection.

It is hypothesized that the magnitude of stratospheric adiabatic temperature changes associated with tropospheric vorticity advection determines the change of intensity of sea-level cyclones and anticyclones. This hypothesis will be evaluated through comparison of the previously investigated intensification cases with other, non-intensification cases.