Revisiting the Relationship among Metrics of Tropical Expansion

Waugh, D.W.; Grise, K.M.; Seviour, W.J.M.; Davis, S.M.; Davis, N.; Adam, O.; Son, S.-W.; Simpson, I.R.; Staten, P.W.; Maycock, A.C.; Ummenhofer, C.C.; Birner, T.; Ming, Alison ORCID: https://orcid.org/0000-0001-5786-6188. 2018 Revisiting the Relationship among Metrics of Tropical Expansion. Journal of Climate, 31 (18). 7565-7581. https://doi.org/10.1175/JCLI-D-18-0108.1

Before downloading, please read NORA policies.

Preview

Text © Copyright 2018 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. All AMS journals and monograph publications are registered with the Copyright Clearance Center (http://www.copyright.com). Questions about permission to use materials for which AMS holds the copyright can also be directed to permissions@ametsoc.org. Additional details are provided in the AMS Copyright Policy statement, available on the AMS website (http://www.ametsoc.org/CopyrightInformation). jcli-d-18-0108.1.pdf - Published Version Download (1MB) | Preview

Abstract/Summary

There is mounting evidence that the width of the tropics has increased over the last few decades, but there are large differences in reported expansion rates. This is, likely, in part due to the wide variety of metrics that have been used to define the tropical width. Here we perform a systematic investigation into the relationship among nine metrics of the zonal-mean tropical width using preindustrial control and abrupt quadrupling of CO2 simulations from a suite of coupled climate models. It is shown that the latitudes of the edge of the Hadley cell, the midlatitude eddy-driven jet, the edge of the subtropical dry zones, and the Southern Hemisphere subtropical high covary interannually and exhibit similar long-term responses to a quadrupling of CO2. However, metrics based on the outgoing longwave radiation, the position of the subtropical jet, the break in the tropopause, and the Northern Hemisphere subtropical high have very weak covariations with the above metrics and/or respond differently to increases in CO2 and thus are not good indicators of the expansion of the Hadley cell or subtropical dry zone. The differing variability and responses to increases in CO2 among metrics highlights that care is needed when choosing metrics for studies of the width of the tropics and that it is important to make sure the metric used is appropriate for the specific phenomena and impacts being examined.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1175/JCLI-D-18-0108.1
ISSN:	0894-8755
Additional Keywords:	Hadley circulation, hydrologic cycle, meridional overturning circulation
Date made live:	28 Aug 2018 08:53 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/520817

Actions (login required)

View Item

Document Downloads

More statistics for this item...