Publication Abstracts
Holzer et al. 2012
Holzer, M., C. Orbe, and F.W. Primeau, 2012: Stratospheric mean residence time and mean age on the tropopause: Connections and implications for observational constraints. J. Geophys. Res., 117, no. D12, doi:10.1029/2012JD017547.
Stratospheric mean residence time τ̅ and mean age on the tropopause ΓΩ are shown to measure physically distinct aspects of stratospheric transport. Both ΓΩ and τ̅ are mean transit times through the stratosphere of air that enters through tropopause region Ωi and exits through region Ωf, but they represent averages over different populations of fluid elements. The averaging for ΓΩ is based on the population of fluid elements exiting the stratosphere, while τ̅ is based on the population of Ωi → Ωf fluid elements residing in the stratosphere. Thus, ΓΩ is the mean age on exit, while is the expected mean residence time in the interior of the stratosphere. The physical basis for defining and robustly computing both timescales is the one-way stratosphere-to-troposphere flux of air labeled with the boundary-propagator Green function, G. By re-expressing the boundary-value problem for G in terms of first-order loss in a tropopause layer with a timescale τc in the limit τc → 0, we show that both τ̅ and ΓΩ can be obtained as ratios of moments of G extrapolated to the tropopause. One obtains τ̅ = ΓΩ + 2Δ2/ΓΩ, where Δ quantifies the width of the transit-time distribution. Because the moments of G can be estimated from the mixing ratio of transient trace gases, it is in principle possible to estimate from measurements of two independent transient tracers. The distinctness of τ̅ and ΓΩ is elucidated using idealized models.
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BibTeX Citation
@article{ho09600r,
author={Holzer, M. and Orbe, C. and Primeau, F. W.},
title={Stratospheric mean residence time and mean age on the tropopause: Connections and implications for observational constraints},
year={2012},
journal={Journal of Geophysical Research},
volume={117},
number={D12},
doi={10.1029/2012JD017547},
}
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RIS Citation
TY - JOUR ID - ho09600r AU - Holzer, M. AU - Orbe, C. AU - Primeau, F. W. PY - 2012 TI - Stratospheric mean residence time and mean age on the tropopause: Connections and implications for observational constraints JA - J. Geophys. Res. JO - Journal of Geophysical Research VL - 117 IS - D12 DO - 10.1029/2012JD017547 ER -
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