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Abstract Previous studies demonstrate that the Madden‐Julian Oscillation (MJO) modulates tropical cyclone (TC) activity over various locations worldwide. Since TCs are associated with anomalous large‐scale circulations, they can influence the development of the MJO. However, the impact of TC on the MJO has not been thoroughly examined. This study investigates the influence of TC‐associated processes on the MJO development based on the analysis of a case observed during the Dynamics of the Madden‐Julian Oscillation field campaign. During the suppressed phase before the December 2011 MJO initiation, two TCs were active in the southern Tropical Indian Ocean (TIO). A dry air band within 10°S‐Eq is sustained by TC‐induced horizontal advection and descent, inhibiting large‐scale convection in the southern equatorial IO. Consequently, convection is triggered and develops only in the northern TIO around Eq‐10°N. The MJO initiates as convection develops south of the equator after the TCs dissipate.
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Relative Roles of Preconditioning Moistening and Global Circumnavigating Mode on the MJO Convective Initiation During DYNAMO
Abstract The relative importance of preconditioning moistening and global circumnavigating mode in the convective initiation of the October 2011 Madden–Julian Oscillation (MJO) event observed during the Dynamics of the Madden–Julian Oscillation (DYNAMO) field campaign is investigated using a series of convection‐permitting regional model simulations. It is demonstrated that the MJO convective initiation is largely controlled by the global circumnavigating mode at the intraseasonal scales. Rapid moistening closely related to this eastward propagating mode a few days prior to the MJO active phase is crucial to the initiation of deep convection and enhanced rainfall. This moistening process nevertheless cannot be accurately described by the “discharge‐recharge” hypothesis, which speculates the importance a gradual moisture buildup over an approximately 2‐week period leading to the arrival of the active MJO phase.
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- Award ID(s):
- 1712290
- PAR ID:
- 10457240
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 46
- Issue:
- 2
- ISSN:
- 0094-8276
- Page Range / eLocation ID:
- p. 1079-1087
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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