Academic Commons

Articles

Internal Variability of the Winter Stratosphere. Part II: Time-Dependent Forcing

Scott, R. K.; Polvani, Lorenzo M.; Waugh, D. W.

This paper considers the effect of time-dependent lower boundary wave forcing on the internal variability found to appear spontaneously in a stratosphere-only model when the forcing is perfectly steady. While the time-dependent forcing is found to modulate the internal variability, leading in some cases to frequency locking of the upper-stratospheric response to the forcing, the temporal and spatial structure of the variability remains similar to the case when the forcing is time independent. Experiments with a time-periodic modulation of the forcing amplitude indicate that the wave flux through the lower boundary is only partially related to the instantaneous forcing, but is more significantly influenced by the condition of the polar vortex itself. In cases of purely random wave forcing with zero time mean, the stratospheric response is similar to that obtained with steady forcing of magnitude equal to the root-mean-square of the time-varying forcing.

Files

Also Published In

Title
Journal of the Atmospheric Sciences
DOI
https://doi.org/10.1175/2007JAS2619.1

More About This Work

Academic Units
Applied Physics and Applied Mathematics
Published Here
November 4, 2013
Academic Commons provides global access to research and scholarship produced at Columbia University, Barnard College, Teachers College, Union Theological Seminary and Jewish Theological Seminary. Academic Commons is managed by the Columbia University Libraries.