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High resolution simulation of the South Asian monsoon using a variable resolution global climate model

P Sabin, T and Krishnan, R and Ghattas, J and Denvil, S and Dufresne, JL and Hourdin, F and Pascal, T (2013) High resolution simulation of the South Asian monsoon using a variable resolution global climate model. Climate Dynamics, 41 (1). pp. 173-194.

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This study examines the feasibility of using a variable resolution global general circulation model (GCM), with telescopic zooming and enhanced resolution (~35 km) over South Asia, to better understand regional aspects of the South Asian monsoon rainfall distribution and the interactions between monsoon circulation and precipitation. For this purpose, two sets of ten member realizations are produced with and without zooming using the LMDZ (Laboratoire Meteorologie Dynamique and Z stands for zoom) GCM. The simulations without zoom correspond to a uniform 1° × 1° grid with the same total number of grid points as in the zoom version. So the grid of the zoomed simulations is finer inside the region of interest but coarser outside. The use of these finer and coarser resolution ensemble members allows us to examine the impact of resolution on the overall quality of the simulated regional monsoon fields. It is found that the monsoon simulation with high-resolution zooming greatly improves the representation of the southwesterly monsoon flow and the heavy precipitation along the narrow orography of the Western Ghats, the northeastern mountain slopes and northern Bay of Bengal (BOB). A realistic Monsoon Trough (MT) is also noticed in the zoomed simulation, together with remarkable improvements in representing the associated precipitation and circulation features, as well as the large-scale organization of meso-scale convective systems over the MT region. Additionally, a more reasonable simulation of the monsoon synoptic disturbances (lows and disturbances) along the MT is noted in the high-resolution zoomed simulation. On the other hand, the no-zoom version has limitations in capturing the depressions and their movement, so that the MT zone is relatively dry in this case. Overall, the results from this work demonstrate the usefulness of the high-resolution variable resolution LMDZ model in realistically capturing the interactions among the monsoon large-scale dynamics, the synoptic systems and the meso-scale convective systems, which are essential elements of the South Asian monsoon system.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer-Verlag
Uncontrolled Keywords: atmospheric dynamics; climate modeling; convective system; feasibility study; general circulation model; mesoscale meteorology; model test; model validation; moisture flux; monsoon; numerical model; precipitation assessment; precipitation intensity; rainfall; summer; synoptic meteorology, Bay of Bengal; Indian Ocean; South Asia
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 18 Nov 2015 05:11
Last Modified: 18 Nov 2015 05:11

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