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Hadley cell emergence and extent in axisymmetric, nearly inviscid, planetary atmospheres

Hill, Spencer A. and Bordoni, Simona and Mitchell, Jonathan L. (2018) Hadley cell emergence and extent in axisymmetric, nearly inviscid, planetary atmospheres. . (Submitted) http://resolver.caltech.edu/CaltechAUTHORS:20181210-111748671

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Abstract

The authors consider constraints from axisymmetric, nearly inviscid theory on Hadley cell emergence and extent in dry planetary atmospheres. Existing versions of the well-known Hide's constraint relating Hadley cell emergence to the distributions of absolute angular momentum (M) and the vertical component of absolute vorticity (η) are unified, amounting to any of M > Ωa^2, M < 0, or fη < 0 occurring at any latitude. The M < 0 condition coincides with the gradient-balanced zonal wind in radiative convective equilibrium (RCE; u_(rce)) becoming non-real valued. The resulting angular momentum conserving (AMC) circulation must span all latitudes where any of these conditions are met or where u_(rce) exceeds the AMC zonal wind (u_(amc)) corresponding to planetary angular momentum at the latitude of the circulation's ascent branch (φ_a), but a generally valid prognostic theory for φa remains elusive. Nevertheless, given a diagnosed φ_a, the u_(rce) > u_(amc) condition provides a simple explanation for why cross-equatorial Hadley circulations typically extend as far into the winter- as the summer hemisphere. The classical "equal-area" models predict φ_a but typically must be solved numerically and always predict φ)a at or poleward of the RCE forcing maximum (φ_m) for φ_m ≠ 0. In an idealized dry general circulation model, a pole-to-pole cross-equatorial Hadley cell emerges if the corresponding RCE state meets some combination of these extent criteria over the entire summer hemisphere. Conversely, the cell edge and φ_a sit far equatorward of φ_m if those criteria are not satisfied near φ_m.


Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription
https://arxiv.org/abs/1810.11105arXivDiscussion Paper
ORCID:
AuthorORCID
Hill, Spencer A.0000-0001-8672-0671
Bordoni, Simona0000-0003-4771-3350
Additional Information:We thank Sean Faulk and Alex Gonzalez for discussions that informed this work and Martin Singh for sharing his valuable insights. S.A.H. was supported by a National Science Foundation (NSF) Atmospheric and Geospace Sciences (AGS) Postdoctoral Research Fellowship, award #1624740. S.B. was supported by NSF award AGS-1462544.
Funders:
Funding AgencyGrant Number
NSF Postdoctoral FellowshipAGS-1624740
NSFAGS-1462544
Record Number:CaltechAUTHORS:20181210-111748671
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20181210-111748671
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91639
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:10 Dec 2018 19:30
Last Modified:10 Dec 2018 19:30

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