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Phase speed spectra of transient eddy fluxes and critical layer absorptionTropospheric zonal mean eddy fluxes of heat and momentum, and the divergence of the Eliassen-Palm flux, are decomposed into contributions from different zonal phase speeds. Data analyzed are the European Center for Medium Range Weather Forecasts operational global analyses covering 1980-1987. Eastward moving medium-scale waves (zonal waves 4-7) dominate the spectra of lower tropospheric heat fluxes in both hemispheres and all seasons. Upper tropospheric wave flux spectra are similar to the low level spectra in midlatitudes, but shift to slower zonal phase speeds as low latitudes are approached. The cause of this shift is the selective absorption of faster moving components in midlatitudes as the waves propagate meridionally. Latitude-phase speed distributions of eddy fluxes are constructed and compared to the zonal mean wind structure. These results demonstrate that upper tropospheric eddies break and decelerate the zonal mean flow approximately 10-20 deg in latitude away from their critical line (where phase speed equals zonal wind speed). Comparisons are also made with results from the middle stratosphere.
Document ID
19910045765
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Randel, William J.
(NCAR Boulder, CO, United States)
Held, Isaac M.
(NOAA, Geophysical Fluid Dynamics Laboratory, Princeton NJ, United States)
Date Acquired
August 14, 2013
Publication Date
March 1, 1991
Publication Information
Publication: Journal of the Atmospheric Sciences
Volume: 48
ISSN: 0022-4928
Subject Category
Meteorology And Climatology
Accession Number
91A30388
Funding Number(s)
CONTRACT_GRANT: NASA ORDER W-16215
Distribution Limits
Public
Copyright
Other

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