edu.ucar.opensky::articles:25536 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T22:42:53.319162 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d71n84vw The influence of shear on deep convection initiation. Part II: simulations 2022-06-01T00:00:00Z publication https://n2t.org/ark:/85065/d71n84vw https://doi.org/10.1175/JAS-D-21-0144.1 Peters, J. M. author Morrison, Hugh author Nelson, T. C. author Marquis, J. N. author Mulholland, J. P. author Nowotarski, C. J. author UCAR/NCAR - Library publisher This study evaluates a hypothesis for the role of vertical wind shear in deep convection initiation (DCI) that was introduced in Part I by examining behavior of a series of numerical simulations. The hypothesis states, "Initial moist updrafts that exceed a width and shear threshold will 'root' within a progressively deeper steering current with time, increase their low-level cloud-relative flow and inflow, widen, and subsequently reduce their susceptibility to entrainment-driven dilution, evolving toward a quasi-steady self-sustaining state." A theoretical model that embodied key elements of the hypothesis was developed in Part I, and the behavior of this model was explored within a multidimensional environmental parameter space. Remarkably similar behavior is evident in the simulations studied here to that of the theoretical model, both in terms of the temporal evolution of DCI and in the sensitivity of DCI to environmental parameters. Notably, both the simulations and theoretical model experience a bifurcation in outcomes, whereby nascent clouds that are narrower than a given initial radius R-0 threshold quickly decay and those above the R-0 threshold undergo DCI. An important assumption in the theoretical model, which states that the cloud-relative flow of the background environment V-CR determines cloud radius R, is scrutinized in the simulations. It is shown that storm-induced inflow is small relative to V-CR beyond a few kilometers from the updraft edge, and V-CR therefore plays a predominant role in transporting conditionally unstable air to the updraft. Thus, the critical role of V-CR in determining R is validated. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2022 American Meteorological Society. None eng geoscientificInformation