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Solsticial Hadley Cell Ascending Edge Theory from Supercriticality.
- Source :
-
Journal of the Atmospheric Sciences . Jun2021, Vol. 78 Issue 6, p1999-2011. 13p. 7 Graphs. - Publication Year :
- 2021
-
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 sinφ, 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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00224928
- Volume :
- 78
- Issue :
- 6
- Database :
- Academic Search Index
- Journal :
- Journal of the Atmospheric Sciences
- Publication Type :
- Academic Journal
- Accession number :
- 150989749
- Full Text :
- https://doi.org/10.1175/JAS-D-20-0341.1