2.5 A Comparison of Vertical Motion Estimates within Supercells during C3LOUD-Ex

Monday, 8 January 2018: 11:30 AM
Room 13AB (ACC) (Austin, Texas)
Peter J. Marinescu, Colorado State Univ., Fort Collins, CO; and S. C. van den Heever, A. J. Drager, L. D. Grant, S. W. Freeman, P. C. Kennedy, and M. M. Bell

Several studies have shown that current cloud-resolving models tend to overestimate the vertical motions in convective storms, and this model bias has many implications for how these models predict atmospheric phenomena, such as the formation of large hail, severe winds, and tornadoes. Doppler radars and lidars have been frequently used for estimating the vertical motions within observed storms and have been considered a ground truth for model evaluation. One goal of the CSU Convective CLoud Outflows and UpDrafts Experiment (C3LOUD-Ex) field campaign was to provide an independent, in situ estimate of vertical velocity using GPS radiosondes launched into storm updrafts. C3LOUD-Ex occurred in July 2016 and May-June 2017 over northeastern Colorado, southeastern Wyoming, and southwestern Nebraska. Over 25 radiosondes were successfully launched into the convective updrafts of 6 supercell storms during the field experiment, and the CSU-CHILL radar was operated to synchronize with either the KCYS or KFTG WSR-88D radar such that dual-Doppler estimates of vertical velocity could be obtained for the same storms. Polarimetric radar data were used to constrain the radiosonde-derived vertical velocity estimates through identifying regions of supercooled liquid and therefore regions where balloons would likely have experienced icing. A comparison of vertical velocity estimates from both the dual-Doppler techniques and radiosonde ascent rates were assessed and will be presented. The vertical velocity estimates presented here can be used to evaluate future model simulations of C3LOUD-Ex supercells in order to better understand the model biases in predicted convective storm vertical motions.
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