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Momentum balance and gravity wave forcing in the mesosphere and lower thermosphere
Author(s) -
Liu H.L.,
Marsh D. R.,
She C.Y.,
Wu Q.,
Xu J.
Publication year - 2009
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 - 10.1029/2009gl037252
Subject(s) - thermosphere , physics , forcing (mathematics) , momentum (technical analysis) , mesosphere , atmospheric sciences , advection , stratopause , ionosphere , geophysics , stratosphere , finance , economics , thermodynamics
Gravity wave forcing (GWF), which is the primary driver of the mesospheric and lower thermospheric (MLT) circulation, is difficult to measure directly. In this work, the zonal mean GWF at extratropical MLT is deduced from measured winds using momentum balance. With the GWF dominating in the MLT, the zonally averaged zonal momentum equation can be simplified to a balance relation between the GWF and the Coriolis force in the extratropics. The meridional advection of zonal momentum makes a higher order contribution to the momentum balance, especially at places where the GWF maximizes. This method is tested with WACCM3 model and preliminary results are obtained from wind measurements by CSU Na lidar and TIMED/TIDI.