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The steady, linear response of the stratosphere to tropospheric forcing
Author(s) -
Karoly David J.,
Hoskins Brian J.
Publication year - 1983
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49710946103
Subject(s) - stratosphere , troposphere , forcing (mathematics) , atmospheric sciences , northern hemisphere , orographic lift , climatology , wavenumber , orography , environmental science , atmospheric wave , potential vorticity , amplitude , vorticity , geology , meteorology , physics , wave propagation , gravity wave , vortex , precipitation , quantum mechanics , optics
A linearized, steady‐state, 15–level numerical model is used to study the stationary planetary wave response of the stratosphere to thermal and orographic forcing in the troposphere. Zonally symmetric basic states representative of northern hemisphere winter and summer conditions are used. Solutions for each zonal wave‐number are considered separately. Eliassen‐Palm cross‐sections are used as a diagnostic of wave propagation. First, several simple thermal and orographic forcing distributions are used in the winter basic state. The response in the stratosphere is sensitive to changes in the zonal wind but its structure is insensitive to the forcing mechanism and to the dissipation used in the model. For representative northern hemisphere thermal and orographic forcing, solutions in winter agree well with observations except for wavenumber one, which has too small an amplitude and an incorrect structure. The solutions for wavenumbers one and two in the troposphere have small differences from those obtained using a similar 5–level model described by us earlier. For higher wavenumbers, the 15–level and 5–level solutions in the troposphere converge, as these waves are trapped in the troposphere. For the summer basic state, the planetary wave response has large amplitude in the troposphere only. It is necessary to use vorticity forcing in the upper troposphere to give a solution with a phase variation similar to that observed in summer.