Evaluating Stratospheric Tropical Width Using Tracer Concentrations
Name
2020JD033081.pdf
Description
Published version
Size
12.09 MB
Format
Adobe PDF
Checksum (MD5)
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Author(s)
Shah, Kasturi S.
Solomon, Susan
Thompson, David W. J.
Kinnison, Douglas E.
Date Issued
October 2020
Journal
Journal of Geophysical Research: Atmospheres
Publisher
American Geophysical Union (AGU)
Citation
Shah, Kasturi S. et al. "Evaluating stratospheric tropical width using tracer concentrations." Journal of Geophysical Research: Atmospheres 125, 21 (October 2020): e2020JD033081. © 2020 American Geophysical Union
Version
Final published version
Abstract
Quantifying the width of the tropics has important implications for understanding climate variability and the atmospheric response to anthropogenic forcing. Considerable effort has been placed on quantifying the width of the tropics at tropospheric levels, but substantially less effort has been placed on quantifying the width at stratospheric levels. Here we probe tropical width in the stratosphere using chemical tracers, which are accessible by direct measurement. Two new tracer-based width metrics are developed, denoted here as the “1σ method” and the gradient weighted latitude (GWL) method. We evaluate widths from three tracers, CH₄, N₂O, and SF₆. We demonstrate that unlike previously proposed stratospheric width methods using tracers, these metrics perform consistently throughout the depth of the stratosphere, at all times of year and on coarse temporal data. The GWL tracer-based widths correlate well with the turnaround latitude and the critical level, where wave dissipation occurs, in the upper and midstratosphere during certain months of the year. In the lower stratosphere, the deseasonalized tracer-based widths near the tropical tropopause correlate with the deseasonalized tropopause-height based metrics. We also find that tracer-tracer width correlations are strongest at pressure levels where their chemical lifetimes are similar. These metrics represent another useful way to estimate stratospheric tropical width and explore any changes under anthropogenic forcing.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1029/2020jd033081
