Meso-beta Scale Numerical Simulation Studies of Terrain-Induced Jet StreakMass/Momentum Perturbations

摘要

An in-depth analysis of observed gravity waves and their relationship toprecipitation bands over the Montana mesonetwork during the 1981 CCOPE case study indicates that there were two episodes of coherent internal gravity waves. One of the fundamental unanswered questions from this research, however, concerns the dynamical processes which generated the observed waves, all of which originated from the region encompassing the borders of Montana, Idaho, and Wyoming. While geostrophic adjustment, shearing instability, and terrain where all implicated separately or in concert as possible wave generation mechanisms, the lack of upper-air data within the wave genesis region made it difficult to rigorously define the genesis processes from observations alone. In this report we employ a mesoscale numerical model to help diagnose the intricate early wave generation mechanisms during the first observed wave episode.