An explosive convective cloud system and its environmental conditions in MJO initiation observed during DYNAMO

Falko Judt, Shuyi S Chen

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

An unusually large, explosive convective cloud system was observed over the equatorial Indian Ocean on 28 November 2011 during the DYNAMO (Dynamics of the Madden-Julian Oscillation (MJO)) field campaign. The significance of this mesoscale convective system (MCS) is its size and explosive development of cold cloud tops (-96°C) during the initiation of a strong MJO event. Observations from the DYNAMO show that the large MCS developed within a well-defined synoptic-scale cyclonic circulation associated with an equatorial low-pressure system with characteristics of a mixed Rossby-gravity wave that dominated the flow in the DYNAMO array. Prior to the development of the MCS, the equatorial flow was characterized by strong vertical wind shear with low-level westerlies and upper level easterlies. A region of decreased wind shear and enhanced upper level divergence emerged concurrently with the passage of the westward moving mixed Rossby-gravity wave-related low-pressure system and convective activity. In situ sounding observations suggest that widespread deep convection upstream of the large MCS may have contributed to the reduction of the upper level easterlies through vertical momentum transport and convective outflow. Both the reduction in vertical wind shear and enhanced low-level convergence induced by the equatorial low-pressure system created a favorable environment for the rapid development of the MCS. This study examines the development of the MCS and the associated synoptic-scale equatorial low-pressure system within the large-scale MJO circulation using in situ sounding observations from DYNAMO, which provide new insights into the interaction between convection and environmental flow during MJO initiation over the equatorial Indian Ocean.

Original languageEnglish (US)
Pages (from-to)2781-2795
Number of pages15
JournalJournal of Geophysical Research C: Oceans
Volume119
Issue number6
DOIs
StatePublished - Mar 27 2014

Fingerprint

Madden-Julian Oscillation
Madden-Julian oscillation
convective cloud
convective system
explosive
low pressure system
wind shear
environmental conditions
low pressure
Gravity waves
Indian Ocean
gravity waves
sounding
Rossby wave
convection
gravity wave
Momentum
upstream
divergence
momentum

Keywords

  • convective organization
  • DYNAMO
  • equatorial low-pressure system
  • MCS
  • MJO
  • shear

ASJC Scopus subject areas

  • Atmospheric Science
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

An explosive convective cloud system and its environmental conditions in MJO initiation observed during DYNAMO. / Judt, Falko; Chen, Shuyi S.

In: Journal of Geophysical Research C: Oceans, Vol. 119, No. 6, 27.03.2014, p. 2781-2795.

Research output: Contribution to journalArticle

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