Systematic Errors in South Asian Monsoon Precipitation: Analysis of CMIP5 and global variable resolution simulations

Friday, December 16, 2016 - 10:50
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Previous studies have noted a systematic bias in the onset of the South Asian monsoon in the CMIP3 and CMIP5 simulations. The delayed onset and consequential mean dry bias of the South Asian monsoon precipitation is investigated using analysis of moisture and energy budget that exploits the weak temperature gradients in the tropics. Models with dry bias in monsoon precipitation over India produce higher precipitation over the equatorial Indian Ocean. From the non-linear relationship between precipitable water and precipitation, the model dry bias and inter-model spread are linked to the model treatment of convection over the equatorial Indian Ocean. A non-hydrostatic global variable resolution model, the Model for Prediction Across Scales (MPAS), is used to explore potential improvements in simulating the South Asian monsoon precipitation. Global variable resolution simulations are performed with regional refinement at resolutions ranging from a few kilometers to 30 km. Analysis will be performed to understand the sensitivity of the simulations to model resolution and the role of convection in the equatorial Indian Ocean on South Asian monsoon precipitation.

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