Phase unlocking and the modulation of tropopause‐level trace gas advection by the quasibiennial oscillation
Name
JGR Atmospheres - 2022 - Shah - Phase Unlocking and the Modulation of Tropopause‐Level Trace Gas Advection by the.pdf
Description
Published version
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3.39 MB
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Adobe PDF
Checksum (MD5)
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Author(s)
Shah, Kasturi
Solomon, Susan
Kinnison, Douglas
Fu, Qiang
Thompson, David WJ
Date Issued
2022
Journal
Journal of Geophysical Research: Atmospheres
Publisher
American Geophysical Union (AGU)
Citation
Shah, Kasturi, Solomon, Susan, Kinnison, Douglas, Fu, Qiang and Thompson, David WJ. 2022. "Phase unlocking and the modulation of tropopause‐level trace gas advection by the quasibiennial oscillation." Journal of Geophysical Research: Atmospheres, 127 (21).
Version
Final published version
Abstract
Open questions about the modulation of near-surface trace gas variability by stratosphere-troposphere tracer transport complicate efforts to identify anthropogenic sources of gases such as CFC-11 and N2O and disentangle them from dynamical influences. In this study, we explore one model's modulation of lower stratospheric tracer advection by the quasi-biennial oscillation (QBO) of stratospheric equatorial zonal-mean zonal winds at 50 hPa. We assess instances of coherent modulation versus disruption through phase unlocking with the seasonal cycle in the model and in observations. We quantify modeled advective contributions to the temporal rate of change of stratospheric CFC-11 and N2O at extratropical and high-latitudes by calculating a transformed Eulerian mean (TEM) budget across isentropic surfaces from a 10-member WACCM4 ensemble simulation. We find that positive interannual variability in seasonal tracer advection generally occurs in the easterly QBO phase, as in previous work, and briefly discuss physical mechanisms. Individual simulations of the 10-member ensemble display phase-unlocking disruptions from this general pattern due to seasonally varying synchronizations between the model's repeating 28-month QBO cycle and the 12-month seasonal cycle. We find that phase locking and unlocking patterns of tracer advection calculations inferred from observations fall within the envelope of the ensemble member results. Our study bolsters evidence for variability in the interannual stratospheric dynamical influence of CFC-11 near-surface concentrations by assessing the QBO modulation of lower stratospheric advection via synchronization with the annual cycle. It identifies a likely cause of variations in the QBO influence on tropospheric abundances.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1029/2021JD036142
