Simulations with the Community Earth System Model, version 2, using the Whole Atmosphere Community Climate Model version 6 [CESM2(WACCM6)] configuration, show evidence of dynamical coupling from the high latitudes of the winter middle atmosphere to the tropics and the middle and high latitudes of the summer hemisphere. Analysis of monthly and daily output covering 195 simulation years indicates that the response in the summer middle and high latitudes has a weak overall magnitude of a few kelvins or less in temperature but has a repeatable pattern whose structure and phase agree with observational studies. Lag correlation indicates that perturbations in wave activity in the winter stratosphere, as quantified by Eliassen–Palm (EP) flux divergence, are accompanied by perturbations in the transformed Eulerian-mean meridional wind extending into the summer hemisphere. There is not an appreciable correlation with momentum forcing in the summer hemisphere by either resolved waves or parameterized gravity waves. The rapid circulation response and the lack of a wave response in the summer hemisphere suggest that the interhemispheric coupling that is simulated in WACCM6 in both the stratosphere and the mesosphere owes its existence to a circulation that develops to restore balance to the zonally averaged state of the atmosphere. This is an alternative explanation for the coupling from the winter stratosphere to the summer mesosphere; previous studies have assumed a necessary role for wave activity in the summer hemisphere.
Satellite observations of middle-atmosphere temperature are used to investigate the short-term global response to planetary wave activity in the winter stratosphere. The focus is on the relation between variations in the winter and summer hemispheres. The analysis uses observations from
There are many instances in which one part of the atmosphere is found to regularly respond to perturbations occurring in a distant region. In this study, we use observations to investigate one such pattern: temperature changes at high altitude (60–100 km) in the summer that follow dynamical changes near the winter pole at 40–60 km. Such analysis is useful to understand which physical processes contribute to the global connectivity and variability of the atmosphere.
- NSF-PAR ID:
- 10375193
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Journal of the Atmospheric Sciences
- Volume:
- 79
- Issue:
- 6
- ISSN:
- 0022-4928
- Page Range / eLocation ID:
- p. 1727-1741
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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