Upscale impact of mesoscale disturbances of tropical convection on synoptic-scale equatorial waves in two-dimensional flows

Qiu Yang, Andrew J. Majda

Research output: Contribution to journalArticle

Abstract

Superclusters on the synoptic scale containing mesoscale systems are frequently organized by convectively coupled equatorial waves (CCEWs). Present-day global models struggle to simulate multiscale tropical convection, and the upscale effects of mesoscale systems are not well understood. A simple two-dimensional multiscale model with prescribed two-scale heating and eddy transfer of momentum and temperature drives the synoptic-scale circulation, successfully reproduces key features of flow fields with a front-to-rear tilt, and compares well with results from a cloud-resolving model (CRM). In the scenario with an elevated upright mean heating, the tilted vertical structure of synoptic-scale circulation is still induced by the upscale impact of mesoscale disturbances. In a faster propagation scenario, the upscale impact becomes less important as a result of competing effects of eddy transfer of momentum and temperature, while the synoptic-scale circulation response to mean heating dominates, in agreement with cloud-resolving models. In the unrealistic scenario with upward-westward-tilted mesoscale heating, positive potential temperature anomalies are induced in the leading edge, which will suppress shallow convection in a moist environment.

Original languageEnglish (US)
Pages (from-to)3099-3120
Number of pages22
JournalJournal of the Atmospheric Sciences
Volume74
Issue number9
DOIs
StatePublished - Sep 1 2017

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equatorial wave
two-dimensional flow
convection
heating
disturbance
momentum
eddy
potential temperature
tilt
temperature anomaly
flow field
temperature
effect

Keywords

  • Atmospheric
  • Convection
  • Mesoscale systems
  • Numerical analysis/modeling
  • Synoptic-scale processes
  • Tropics
  • Waves

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

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title = "Upscale impact of mesoscale disturbances of tropical convection on synoptic-scale equatorial waves in two-dimensional flows",
abstract = "Superclusters on the synoptic scale containing mesoscale systems are frequently organized by convectively coupled equatorial waves (CCEWs). Present-day global models struggle to simulate multiscale tropical convection, and the upscale effects of mesoscale systems are not well understood. A simple two-dimensional multiscale model with prescribed two-scale heating and eddy transfer of momentum and temperature drives the synoptic-scale circulation, successfully reproduces key features of flow fields with a front-to-rear tilt, and compares well with results from a cloud-resolving model (CRM). In the scenario with an elevated upright mean heating, the tilted vertical structure of synoptic-scale circulation is still induced by the upscale impact of mesoscale disturbances. In a faster propagation scenario, the upscale impact becomes less important as a result of competing effects of eddy transfer of momentum and temperature, while the synoptic-scale circulation response to mean heating dominates, in agreement with cloud-resolving models. In the unrealistic scenario with upward-westward-tilted mesoscale heating, positive potential temperature anomalies are induced in the leading edge, which will suppress shallow convection in a moist environment.",
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N2 - Superclusters on the synoptic scale containing mesoscale systems are frequently organized by convectively coupled equatorial waves (CCEWs). Present-day global models struggle to simulate multiscale tropical convection, and the upscale effects of mesoscale systems are not well understood. A simple two-dimensional multiscale model with prescribed two-scale heating and eddy transfer of momentum and temperature drives the synoptic-scale circulation, successfully reproduces key features of flow fields with a front-to-rear tilt, and compares well with results from a cloud-resolving model (CRM). In the scenario with an elevated upright mean heating, the tilted vertical structure of synoptic-scale circulation is still induced by the upscale impact of mesoscale disturbances. In a faster propagation scenario, the upscale impact becomes less important as a result of competing effects of eddy transfer of momentum and temperature, while the synoptic-scale circulation response to mean heating dominates, in agreement with cloud-resolving models. In the unrealistic scenario with upward-westward-tilted mesoscale heating, positive potential temperature anomalies are induced in the leading edge, which will suppress shallow convection in a moist environment.

AB - Superclusters on the synoptic scale containing mesoscale systems are frequently organized by convectively coupled equatorial waves (CCEWs). Present-day global models struggle to simulate multiscale tropical convection, and the upscale effects of mesoscale systems are not well understood. A simple two-dimensional multiscale model with prescribed two-scale heating and eddy transfer of momentum and temperature drives the synoptic-scale circulation, successfully reproduces key features of flow fields with a front-to-rear tilt, and compares well with results from a cloud-resolving model (CRM). In the scenario with an elevated upright mean heating, the tilted vertical structure of synoptic-scale circulation is still induced by the upscale impact of mesoscale disturbances. In a faster propagation scenario, the upscale impact becomes less important as a result of competing effects of eddy transfer of momentum and temperature, while the synoptic-scale circulation response to mean heating dominates, in agreement with cloud-resolving models. In the unrealistic scenario with upward-westward-tilted mesoscale heating, positive potential temperature anomalies are induced in the leading edge, which will suppress shallow convection in a moist environment.

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