Observational Case Studies and Diagnostic Analyses of Long-Lived Large-AmplitudeInertia-Gravity Waves

摘要

AFOSR-funded research projects have included: (1) completion of a nationalclimatology of large-amplitude inertia-gravity wave (IGW) occurrences, (2) completion of a case study from 15-17 November 1987 of a long-lived convective event that featured a complex interplay between wake-low troughs and IGWs, (3) completion of a case study of the 4 January 1994 large-amplitude IGW event over the northeastern United States, and (4) ongoing research designed to elicit the environmental structure (horizontal and vertical) of large-amplitude IGWs. The results from (1) reveal that IGWs are favored in interior regions east of the Rockies while avoiding the mountainous western United States. The analysis from (2) shows that rain-cooled air provides the necessary low-level wave duct for IGWs and wake-low troughs to coexist in an organized convective environment. The results from (3) suggest that vigorous subsynoptic-scale ascent can play the role of surrogate convection in allowing IGW organization and amplification provided that the ascent has roots in a prominent low-level wave duct. Preliminary results from (4) reveal that the environment of large-amplitude IGWs is remarkably similar to warm front environments except that the upper-level jet is stronger and the low-level thermal inversion is better defined in the IGW cases.