Seasonal ventilation of the stratosphere: Robust diagnostics from one-way flux distributions

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JGR Atmospheres - 2013 - Orbe - Seasonal ventilation of the stratosphere Robust diagnostics from one‐way flux.pdf (4.03 MB)

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https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013JD020213

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https://doi.org/10.1002/2013JD020213
 http://hdl.handle.net/11603/26729

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https://orcid.org/0000-0002-7928-0775

Date

2013-12-10

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journal articles
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Citation of Original Publication

Orbe, C., M. Holzer, L. M. Polvani, D. W. Waugh, F. Li, L. D. Oman, and P. A. Newman (2014), Seasonalventilation of the stratosphere: Robust diagnostics from one-way flux distributions,J. Geophys. Res. Atmos.,119, 293–306,doi:10.1002/2013JD020213.

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

We present an analysis of the seasonally varying ventilation of the stratosphere using one-way flux distributions. Robust transport diagnostics are computed using GEOSCCM subject to fixed present-day climate forcings. From the one-way flux, we determine the mass of the stratosphere that is in transit since entry through the tropical tropopause to its exit back into the troposphere, partitioned according to stratospheric residence time and exit location. The seasonalities of all diagnostics are quantified with respect to the month of year (a) when air enters the stratosphere, (b) when the mass of the stratosphere is partitioned, and (c) when air exits back into the troposphere. We find that the return flux, within 3 months since entry, depends strongly on when entry occurred: (34±10)% more of the air entering the stratosphere in July leaves poleward of 45°N compared to air that enters in January. The month of year when the air mass is partitioned is also found to be important: The stratosphere contains about six times more air of tropical origin during late summer and early fall that will leave poleward of 45° within 6 months since entering the stratosphere compared to during late winter to late spring. When the entire mass of the air that entered the stratosphere at the tropics regardless of its residence time is considered, we find that (51±1)% and (39±2)% will leave poleward of 10° in the Nothern Hemisphere (NH) and Southern Hemisphere (SH), respectively.