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Mechanism for northward propagation of boreal summer intraseasonal oscillation: Convective momentum transport
Author(s) -
Kang InSik,
Kim Daehyun,
Kug JongSeong
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl045072
Subject(s) - convection , geology , momentum (technical analysis) , climatology , madden–julian oscillation , atmospheric sciences , zonal and meridional , geophysics , mechanics , physics , finance , economics
This study demonstrates that the momentum transport by cumulus convection plays a significant role in the organization and northward propagation of intraseasonal (ISO) convection anomalies over the Indian and western Pacific regions during boreal summer. A version of Seoul National University's atmosphere‐ocean coupled general circulation model simulates northward propagation when convective momentum transport (CMT) is implemented; the northward propagation disappears when CMT is disabled. An axially symmetric shallow water model with a parameterized CMT is used to understand the role of CMT in the northward propagation of ISO. The basic mechanism of northward propagation is the lower‐level convergence to the north of convection, which is induced by the secondary meridional circulation associated with large momentum mixing by convection in the region of large mean vertical shear. A large mean vertical shear exists in South Asian region during boreal summer.