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Title:Structure of an east coast cyclone derived from airborne radar and model diagnostics
Author(s):Janiszeski, Andrew R.
Advisor(s):Rauber, Robert M.; McFarquhar, Greg M.; Jewett, Brian F.
Department / Program:Atmospheric Sciences
Discipline:Atmospheric Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
finescale structure
east coast cyclone
Abstract:Data from airborne W-band radar along with Weather Research and Forecasting (WRF) Model thermodynamic fields and air-parcel back trajectories from the HYSPLIT model are used to determine causes of finescale features of a northeast U.S. cyclone and link them to synoptic and air mass structure. The storm intensified and propagated along the New England coastline on 2 February 2015. A stratiform echo was observed in the northeast half of the first of four flight legs with more convective echoes on the southwestern half. As the storm moved northeastward, the radar sampled more of the convective southern quadrant of the storm. Convective radar reflectivity echoes were observed across all of the third and fourth flight legs as the stratiform echo had exited the sampling region. The air-parcel back trajectory analysis showed a coherent air mass structure of five trajectory groups distinguished by source location. The interface between two trajectory groups was nearly aligned with one of the WRF modeled potentially unstable layers. Elevated convection observed near cloud top exhibited updrafts of 2 to 3.5 m s-1 and was often located within layers of WRF modeled potential instability. Beneath the elevated convection were many enhanced reflectivity fall streaks that were shaped by the vertical wind shear profile. Turbulent features were observed along a frontal boundary in a highly stable and highly sheared environment with radial velocities of 1 m s-1 upward to 4 m s-1 downward, corresponding to updrafts and downdrafts of ~ 2-3 m s-1. Updrafts of similar magnitude were observed in a marginally stable, sheared environment at or near cloud top. Atmospheric temperature profiles and radial velocity observations supported freezing rain and/or ice pellets in portions of each flight leg. Surface observations of freezing rain in the vicinity of these flight legs were recorded. The data presented display the spatial variability of the finescale structure of an east coast cyclone while determining the cause of such structure and its linkage to the synoptic scale.
Issue Date:2018-04-25
Rights Information:Copyright 2018 Andrew R Janiszeski
Date Available in IDEALS:2018-09-04
Date Deposited:2018-05

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