Improved Simulation of the South Asian Summer Monsoon in a Coupled GCM with a More Realistic Ocean Mixed Layer
Open Access
- 1 May 2012
- journal article
- Published by American Meteorological Society in Journal of the Atmospheric Sciences
- Vol. 69 (5), 1681-1690
- https://doi.org/10.1175/jas-d-11-0235.1
Abstract
Simulation and prediction of the South Asian summer monsoon in a climate model remain a challenge despite intense efforts by the atmosphere and ocean research community. Because the phenomenon arises from the interaction of the atmosphere with the upper ocean, a deficiency in the simulation of the latter can lead to a poor simulation of the atmospheric meridional circulation. This study demonstrates that a significant improvement can be obtained in the simulation of the summer monsoon by correcting a prevailing deficiency in the mixed layer simulation of the Indian Ocean. A particular physical process of the nonbreaking wave–ocean mixing parameterized as Bυ, which has not been considered in any climate model, is included in this study to enhance the vertical mixing in the upper ocean. Results show that the inclusion of this mixing process in a climate model leads to a better simulation of the ocean mixed layer, especially in the regions where the mixing was previously underestimated. The improved mixed layer simulation further results in stronger meridional differential heating, which drives stronger low-level monsoonal winds and results in stronger moisture transport and convergence, especially in the northern Indian Ocean. Moisture convergence into the Bay of Bengal is significantly enhanced and in general the spatial distribution of moisture is more consistent with observations. The directly driven monsoonal winds by the differential heating are further amplified by the resultant latent heating, which generates not only a wind amplitude comparable to the observations but also a correct vertical structure.Keywords
This publication has 41 references indexed in Scilit:
- An Experiment on the Nonbreaking Surface-Wave-Induced Vertical MixingJournal of Physical Oceanography, 2010
- A three-dimensional surface wave–ocean circulation coupled model and its initial testingOcean Dynamics, 2010
- On the Existence of Water Turbulence Induced by Nonbreaking Surface WavesJournal of Physical Oceanography, 2009
- On a wave‐induced turbulence and a wave‐mixed upper ocean layerGeophysical Research Letters, 2006
- On the Interaction of Surface Waves and Upper Ocean TurbulenceJournal of Physical Oceanography, 2006
- Wave‐induced mixing in the upper ocean: Distribution and application to a global ocean circulation modelGeophysical Research Letters, 2004
- Response of a stably stratified atmosphere to large-scale diabatic forcing with applications to wind patters in Brazil and the SahelJournal of Geophysical Research: Atmospheres, 1996
- The role of hydrological processes in ocean‐atmosphere interactionsReviews of Geophysics, 1994
- Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterizationReviews of Geophysics, 1994
- Development of a turbulence closure model for geophysical fluid problemsReviews of Geophysics, 1982