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QBO modulation of the mesopause gravity wave momentum flux over Tierra del Fuego
Author(s) -
Wit R. J.,
Janches D.,
Fritts D. C.,
Hibbins R. E.
Publication year - 2016
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 - 10.1002/2016gl068599
Subject(s) - thermosphere , mesopause , atmospheric sciences , stratosphere , gravity wave , mesosphere , forcing (mathematics) , flux (metallurgy) , physics , middle latitudes , oscillation (cell signaling) , climatology , momentum (technical analysis) , geology , geophysics , gravitational wave , ionosphere , astrophysics , materials science , genetics , biology , metallurgy , finance , economics
The interannual variability of the mesosphere and lower thermosphere (MLT) gravity wave momentum flux over southern midlatitudes (53.7°S) has been studied using more than 7 years of meteor radar observations at Río Grande, Argentina. A modulation, with periods similar to that of the equatorial stratospheric quasi‐biennial oscillation (QBO), is observed in the vertical flux of zonal as well as meridional momentum. The QBO signal is largest in the zonal component during summer and is in phase with the stratospheric QBO at 50 hPa (∼21 km). The relation between the stratospheric QBO and the QBO modulation in the MLT gravity wave forcing (derived from the divergence of the momentum flux) was found to be consistent with that expected from the Holton‐Tan effect coupled to the interhemispheric coupling mechanism. These results provide the first observational support for the existence of the midlatitude gravity wave forcing anomalies as hypothesized in the interhemispheric coupling mechanism.

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