The Coupling of Upper and Lower Tropospheric Jet Streaks and Implications for the Development of Severe Convective Storms

Abstract

Abstract Transverse circulations in the exit and entrance regions of jet streaks are investigated through numerical simulation, a case study, and an application of the isallobaric wind equation in isentropic coordinates, to study the interaction between upper and lower tropospheric jets and the development of severe convective storms. A hybrid isentropic-sigma coordinate numerical model is used to simulate the mass and momentum adjustments associated with a jet streak propagating in a zonal channel. The numerical results depict a two-layer mass adjustment in the exit and entrance region of the jet streak. The results also verify that the isallobaric wind on lower isentropic surfaces is a primary component of the return branches of transverse circulations and is foxed by the two-layer mass adjustment accompanying the propagating jet streak. Results from the case study of a severe weather out- break show that 1) a low-level jet (LLJ) beneath the exit region of an upper tropospheric jet streak is embedded in...