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Formation and Maintenance of the Tropical Cold-Point Tropopause in a Dry Dynamic-Core GCM.
- Source :
-
Journal of the Atmospheric Sciences . Aug2015, Vol. 72 Issue 8, p3097-3115. 19p. 12 Graphs. - Publication Year :
- 2015
-
Abstract
- The formation of the tropical cold-point tropopause (CPT) is examined using a dry primitive equation model driven by the Held-Suarez forcing. Without moist and realistic radiative processes, the dry model successfully reproduces the zonal-mean structure of the CPT. The modeled CPT is appreciably colder (~10 K) than the prescribed equilibrium temperature, and it is maintained by upwelling in the tropical upper troposphere and lower stratosphere (UTLS). A transient simulation starting from an axisymmetric steady state without the CPT shows that the evolution and maintenance of the CPT are closely related to the zonal-mean-flow response to wave driving in the stratosphere. The transformed Eulerian-mean analysis indicates that the wave driving is mostly due to convergence of synoptic-scale waves originating from the midlatitude troposphere and propagating into the subtropical UTLS in this model simulation. The modeled CPT also shows a large sensitivity to increased baroclinicity in the equilibrium temperature. Although planetary-scale waves are not considered in this simulation, the result confirms that wave-driven upwelling in the tropical UTLS is a crucial process for the formation and maintenance of the CPT. In addition, it also implies that synoptic-scale waves may play a nonnegligible role in this mechanism, particularly in the seasons when planetary-scale wave activity in the lower stratosphere is weak. [ABSTRACT FROM AUTHOR]
- Subjects :
- *STRATOSPHERE
*FLUID dynamics
*OCEAN waves
*TEMPERATURE measurements
*TROPOSPHERE
Subjects
Details
- Language :
- English
- ISSN :
- 00224928
- Volume :
- 72
- Issue :
- 8
- Database :
- Academic Search Index
- Journal :
- Journal of the Atmospheric Sciences
- Publication Type :
- Academic Journal
- Accession number :
- 108698298
- Full Text :
- https://doi.org/10.1175/JAS-D-14-0338.1