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) : Hobson, Dennis A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a265333.pdf


Report Date : Dec 1992


Pagination or Media Count : 143


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 storm's 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


Descriptors :   *STORMS , *CONVECTION(ATMOSPHERIC) , VELOCITY , FREQUENCY , CLOUDS , THESES , RADIOSONDES , REFLECTIVITY , ATMOSPHERIC MOTION , RADIATIVE TRANSFER , RADAR , FLOW FIELDS


Subject Categories : Meteorology


Distribution Statement : APPROVED FOR PUBLIC RELEASE