Letter abstract
Nature Geoscience 1, 515 - 519 (2008)
Published online: 6 July 2008 | doi:10.1038/ngeo248
Subject Category: Atmospheric science
Monsoons as eddy-mediated regime transitions of the tropical overturning circulation
Simona Bordoni1,2 & Tapio Schneider1
Monsoons are generally viewed as planetary-scale sea-breeze circulations, caused by contrasts in the thermal properties between oceans and land surfaces that lead to thermal contrasts upon radiative heating1, 2. But the radiative heating evolves gradually with the seasons, whereas the onset of monsoon precipitation, and the associated circulation changes such as reversal of surface winds, occur rapidly3, 4. Here we use reanalysis data to show that the onset of the Asian monsoon marks a transition between two circulation regimes that are distinct in the degree to which eddy momentum fluxes control the strength of the tropical overturning circulation. Rapid transitions of the circulation between the two regimes can occur as a result of feedbacks between large-scale extratropical eddies and the tropical circulation5. Using simulations with an aquaplanet general circulation model, we demonstrate that rapid, eddy-mediated monsoon transitions occur even in the absence of surface inhomogeneities, provided the planet surface has sufficiently low thermal inertia. On the basis of these results, we propose a view of monsoons in which feedbacks between large-scale extratropical eddies and the tropical circulation are essential for the development of monsoons, whereas surface inhomogeneities such as land-sea contrasts are not.
- California Institute of Technology, Pasadena, California 91125, USA
- National Center for Atmospheric Research, Boulder, Colorado 80307, USA
Correspondence to: Simona Bordoni1,2 e-mail: bordoni@gps.caltech.edu
MORE ARTICLES LIKE THIS
These links to content published by NPG are automatically generated.
NEWS AND VIEWS
Meteorology: Anomalous El Ni???o of 1982?83Nature News and Views (01 Sep 1983)
Clearer circulation on UranusNature News and Views (15 Jan 1987)
See all 6 matches for News And ViewsRESEARCH
The range and unity of planetary circulationsNature Article (27 May 1982)
A topographically forced asymmetry in the martian circulation and climateNature Letters to Editor (21 Mar 2002)
See all 59 matches for Research
