Accession Number:

ADA265333

Title:

Evolution of Area-Averaged Vertical Velocity in the Convective Region of a Midlatitude Squall Line

Descriptive Note:

Master's thesis,

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s):

Report Date:

1992-12-01

Pagination or Media Count:

143.0

Abstract:

The evolution of area-averaged vertical velocity over a 50 km length segment of the convective region of the 10 - 11 June 1985 squall line system observed during PRESTORM Preliminary Regional Experiment for Stormscale Operational and Research Meteorology - Central Phase was examined over a period of 43 minutes during the storms mature stage. Seven dual-Doppler analyses with a temporal resolution of 6 - 10 minutes were used to determine vertical velocity. The vertical velocity was then sampled within the boundaries of an objectively defined convective region delineated by low and mid-level thresholds of reflectivity and reflectivity gradient. Variations in area- averaged vertical velocity profiles suggested significant mesoscale evolution of the convective region over the period of analysis. This notion was supported by examination of area-averaged reflectivity profiles, and the distribution of vertical velocity magnitudes as a function of height, as well as cross-sections of vertical velocity, reflectivity, and storm-relative flow fields. Comparison of the observed changes in the convective drafts, reflectivity structure, and storm-relative flow, with those of numerical simulations of squall line evolution suggested that the convective region had undergone a rather quick transition from a stronger, developing state to a much weaker, mature state

Subject Categories:

  • Meteorology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE