@article{b7e8302e48694d178a51d50a9af32ef3,
title = "Stratospheric Adiabatic Mixing Rates Derived From the Vertical Gradient of Age of Air",
abstract = "The circulation of the stratosphere transports important trace gases, including ozone, and can be thought of as having a fast horizontal mixing component and a slow meridional overturning component. Measuring the strength of the circulation directly is not possible, and so it must be inferred from tracer measurements. Long-lived trace gases can be related to the idealized tracer age of air, which describes how long an air parcel has been in the stratosphere. In this paper, we derive a quantitative relationship between the vertical gradient of age and the horizontal mixing between the tropics and the extratropics using a “leaky pipe” framework in isentropic coordinates. Mixing rates of air into and out of the tropics are related to the vertical gradient of age in the tropics and in the extratropics, respectively. The derivation is repeated with the hemispheres separated so that the vertical structure of the mixing in the two hemispheres can be compared directly. These theories are applied to output from an idealized model of the stratosphere and from a realistic chemistry-climate model to test our assumptions and calculate the mixing rates in the models. We then perform a quantitative comparison of the mixing rates in the Northern and Southern hemispheres along with an examination of where such a separation is valid. Finally, we perform a very preliminary calculation of mixing efficiency with satellite data to demonstrate the use of the mixing metric to compare mixing in models and data.",
keywords = "age of air, stratospheric circulation",
author = "Marianna Linz and Plumb, {R. Alan} and Aman Gupta and Gerber, {Edwin P.}",
note = "Funding Information: First, the authors would like to thank Douglas E. Kinnison for providing the WACCM data for this study. WACCM is a component of the Community Earth System Model (CESM), which is supported by the National Science Foundation (NSF) and the Office of Science of the U.S. Department of Energy. Computing resources were provided by NCAR{\textquoteright}s Climate Simulation Laboratory, sponsored by NSF and other agencies. This research was enabled by the computational and storage resources of NCAR{\textquoteright}s Computational and Information System Laboratory (CISL). We would also like to thank our very helpful reviewers. This research was conducted with Government support for M. Linz under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a. M. Linz was also partially supported by the NSF award AGS-1608775. This work was also supported in part by the National Science Foundation grants AGS-1547733 to MIT and AGS-1546585 and AGS-1852727 to NYU. Funding Information: First, the authors would like to thank Douglas E. Kinnison for providing the WACCM data for this study. WACCM is a component of the Community Earth System Model (CESM), which is supported by the National Science Foundation (NSF) and the Office of Science of the U.S. Department of Energy. Computing resources were provided by NCAR{\textquoteright}s Climate Simulation Laboratory, sponsored by NSF and other agencies. This research was enabled by the computational and storage resources of NCAR{\textquoteright}s Computational and Information System Laboratory (CISL). We would also like to thank our very helpful reviewers. This research was conducted with Government support for M. Linz under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a. M. Linz was also partially supported by the NSF award AGS‐1608775. This work was also supported in part by the National Science Foundation grants AGS‐1547733 to MIT and AGS‐1546585 and AGS‐1852727 to NYU. Publisher Copyright: {\textcopyright} 2021 The Authors.",
year = "2021",
month = nov,
day = "16",
doi = "10.1029/2021JD035199",
language = "English (US)",
volume = "126",
journal = "Journal of Geophysical Research: Atmospheres",
issn = "2169-897X",
publisher = "Wiley-Blackwell Publishing Ltd",
number = "21",
}