A suppression of polar stratospheric warming due to planetary wave saturation (abstract)

• Main Authors: Tanaka,Hiroshi, Ushimaru,Shinji
• Format: Report
• Language: English
• Published: Water Research Institute, Nagoya University/Water Research Institute, Nagoya University 1989
• Subjects: Antarctic; The Antarctic; Antarc*; Antarctica; Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3579; http://id.nii.ac.jp/1291/00003579/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3579&item_no=1&attribute_id=18&file_no=1

Based on the fact that the total ozone content is highly correlated to the atmospheric temperature, a model simulation was carried out to produce a cold core pattern over the Antarctic lower stratosphere, which is sustained during ozone hole events. The Matsuno model, originally used to simulate the stratospheric sudden warming, is adopted here, together with incorporation of Newtonian cooling. A key factor to suppress the stratospheric warming and, instead, to form a cold core pattern is Lindzen-Schoeberl-type saturation condition of stationary planetary waves, which is a simplified form of barotropic instability. Results of the simulation demonstrate that reasonable constraints of the wave saturation (e.g., 700m in the maximum) for the wavenumber 1 planetary waves lead to a typical cold core pattern if realistic forcing in the southern hemisphere (e.g., 200m) is set at the tropopause level. Rapid rotation of the pattern, which is quite analogous to the observed rotation of total ozone pattern by Nimbus 7 TOMS, is also well simulated. A significant acceleration of westerly wind and poleward shift of its axis, which could be induced by EP flux divergences associated with the planetary wave saturation, seem to be responsible for formation of indirect meridional circulation, upward in the polar region and downward in mid-latitudes, and the resulting formation of cold core pattern over Antarctica. This mechanism also seems to be responsible for rapid rotation of the pattern. The suppression of polar stratospheric warming tends to result in a recent dramatic ozone decrease over Antarctica only if some heterogeneous chemical reaction processes are superposed. We need to include nonlinear wave interactions of planetary waves for the next step.