A case study of terrain influences on upscale convective growth of a supercell

Jake P. Mulholland, Stephen W. Nesbitt, Robert J. Trapp

Research output: Contribution to journalArticle

Abstract

Satellite- and ground-based radar observations have shown that the northern half of Argentina, South America, is a region susceptible to rapid upscale growth of deep moist convection into larger organized mesoscale convective systems (MCSs). In particular, the complex terrain of the Sierras de Córdoba is hypothesized to be vital to this upscale-growth process. A canonical orographic supercell-to-MCS transition case study was analyzed to determine the influence that complex terrain had on processes governing upscale convective growth. High-resolution numerical modeling experiments were conducted in which the terrain height of the Sierras de Córdobawas systematicallymodified by raising or lowering the elevation of terrain above 1000m. The alteration of the terrain lead to both direct and indirect effects on storm morphology. A direct effect included terrain blocking of cold pools, whereas indirect effects included terrain-induced variations in pertinent storm environmental parameters (e.g., vertical wind shear, convective available potential energy). When the terrain was raised, low-level and deep-layer vertical wind shear increased,mixed-layer convective available potential energy decreased, deep moist convection initiated earlier, and cold pools were blocked and generally became stronger and deeper. The reverse occurred when the terrain was lowered, resulting in aweaker supercell that did not grow upscale into an MCS. The control simulation supercell displayed the deepest cold pool and correspondingly fastest transition fromsupercell toMCS, potentially revealing that the unique terrain configuration of the Sierras de Córdoba was supportive of the observed rapid upscale convective growth of this orographic supercell.

Original languageEnglish (US)
Pages (from-to)4305-4324
Number of pages20
JournalMonthly Weather Review
Volume147
Issue number12
DOIs
StatePublished - 2019

ASJC Scopus subject areas

  • Atmospheric Science

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