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A numerical study of upward‐propagating gravity waves in two different MJO phases
Author(s) -
Horinouchi Takeshi
Publication year - 2008
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 - 10.1029/2008gl034992
Subject(s) - madden–julian oscillation , troposphere , convection , stratosphere , gravity wave , atmospheric sciences , oscillation (cell signaling) , phase (matter) , atmosphere (unit) , geology , climatology , wavelength , forcing (mathematics) , kelvin wave , equatorial waves , geophysics , wave propagation , physics , meteorology , geodesy , optics , equator , chemistry , biochemistry , quantum mechanics , latitude
Convectively generated atmospheric gravity waves that propagate into the equatorial stratosphere were investigated using a cloud resolving model. Numerical simulations were conducted to study wave generation during convectively inactive and active phases in a cycle of the Madden‐Julian oscillation, which occurred during an observational campaign conducted in Sumatra. Greater convective activity during the active phase caused stronger disturbances in the troposphere at relatively low phase speeds less than about 20m/s than the inactive phase. However, the contrast was weaker at higher phase speeds. Furthermore, the vertical structure of convective forcing in the inactive phase was more suitable to excite waves with wavelength longer than twice the depth of convection. Owing to the combination of these factors, upward gravity wave propagation was significantly enhanced during the inactive phase. This study demonstrates the necessity to study convection spectrally to investigate possible links between intraseasonal variabilities in the troposphere and the middle atmosphere.