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Title: Solsticial Hadley Cell ascending edge theory from supercriticality
Abstract How far the Hadley circulation’s ascending branch extends into the summer hemisphere is a fundamental but incompletely understood characteristic of Earth’s climate. Here, we present a predictive, analytical theory for this ascending edge latitude based on the extent of supercritical forcing. Supercriticality sets the minimum extent of a large-scale circulation based on the angular momentum and absolute vorticity distributions of the hypothetical state were the circulation absent. We explicitly simulate this latitude-by-latitude radiative-convective equilibrium (RCE) state. Its depth-averaged temperature profile is suitably captured by a simple analytical approximation that increases linearly with sin φ , where φ is latitude, from the winter to the summer pole. This, in turn, yields a one-third power-law scaling of the supercritical forcing extent with the thermal Rossby number. In moist and dry idealized GCM simulations under solsticial forcing performed with a wide range of planetary rotation rates, the ascending edge latitudes largely behave according to this scaling.  more » « less
Award ID(s):
1912673
PAR ID:
10274671
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Journal of the Atmospheric Sciences
ISSN:
0022-4928
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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