Analysis of three-dimensional Eliassen-Palm fluxes in the lower stratosphere |
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Authors: | Yu A Zyulyaeva E A Zhadin |
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Institution: | 1.Shirshov Institute of Oceanology,Russian Academy of Sciences,Moscow,Russia |
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Abstract: | Using the monthly mean NCEP/NCAR reanalysis dataset, the three-dimensional Eliassen-Palm (EP) fluxes of quasi-stationary wave
propagation in the lower stratosphere were computed for each month from November to March for the period from 1958 to 2007.
It is shown that the upward planetary wave propagation from the troposphere to the stratosphere generally occurs over the
northern Eurasia, while their weak downward propagation is observed in Labrador and southern Greenland regions in the lower
stratosphere. Interannual variations of the vertical EP fluxes also have the dipole-like spatial pattern with the opposite
anomalies in the West and East hemispheres which are most prominent in January–February. Significant differences in the interaction
of the zonal circulation of the stratosphere in the beginning of winter (November–December) and mid-to-late winter (January–March)
are revealed. Intensification of the planetary waves’ penetration into the stratosphere in December causes changes in the
stratospheric dynamics, creating the “preconditions” for the stratospheric warming appearances in January, but such a mechanism
is not detected in February. In the years with the cold polar vortex, the “stratospheric bridge” is formed with the strengthening
of the upward EP flux over the northern Eurasia and downward EP flux over the North Atlantic. |
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