Mechanisms limiting the southward extent of the South American summer monsoon

Citation
C. Chou et Jd. Neelin, Mechanisms limiting the southward extent of the South American summer monsoon, GEOPHYS R L, 28(12), 2001, pp. 2433-2436
Citations number
14
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOPHYSICAL RESEARCH LETTERS
ISSN journal
0094-8276 → ACNP
Volume
28
Issue
12
Year of publication
2001
Pages
2433 - 2436
Database
ISI
SICI code
0094-8276(20010615)28:12<2433:MLTSEO>2.0.ZU;2-U
Abstract
An intermediate atmospheric model coupled with a simple land-surface model and a mixed-layer ocean model is used to examine effects that determine the southward extension of summer precipitation over South America. The extent of the continental convergence zone is mainly determined by two mechanisms , which we term ventilation and the "interactive Rodwell-Hoskins mechanism" . Ventilation refers to the import into South America of low moist static e nergy air from the cooler ocean, primarily the Pacific. In the interactive Rodwell-Hoskins mechanism, Rossby-wave-induced subsidence to the west of th e diabatic heating interacts with the convection zone. Because of the shape of South America, the interactive Rodwell-Hoskins mechanism is of comparab le importance to ventilation. Soil moisture feedback also helps limit polew ard movement of the continental convergence zone, but its effect is relativ ely weak compared to the above two effects. The characteristic northwest-so utheast tilt of the continental convergence zone appears to be due to a com bination of ventilation and the interactive Rodwell-Hoskins mechanism.