Effects of diabatic heating on the ageostrophic circulation of an upper tropospheric jet streak.

Abstract

The interaction between the mass circulations within a mesoscale convective complex (MCC) and the entrance region of an upper troposheric polar jet streak is examined to investigate mechanisms responsible for linking these two scales of motion. The results analyzed within isentropic coordinates establish that latent heating in the MCC modified the direct mass circulation in the jet streak entrance region through the forcing of adiabatic components of ageostrophic motion. Discrepancies of 20 m s SUP - SUP 1 between actual and geostrophic momentum shows that the rapid evolution of ageostrophic motion within the shorter time scales of MCCs limits the applicability of geostrophic momentum theory in prescribing the structure of ageostrophic motion. (R.I.H.)