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Simulating the Tibetan Plateau Summer Monsoon

Duan, A., Hu, J. and Xiao, Z. 2013. The Tibetan Plateau summer monsoon in the CMIP5 simulations. Journal of Climate 26: 7747-7766.
Duan et al. (2013) write that, historically, "most CGCMs [coupled general circulation models] do not simulate the spatial or inter-annual variation of monsoon precipitation accurately," specifically noting that "Zhou and Yu (2006) showed that, over China, the estimated annual precipitation over East Asia exceeds the observed estimates in all models in AR4 [the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC)]." However, they also write that "ongoing development since AR4 is expected to considerably improve the ability of the climate models to simulate monsoon precipitation patterns and variability resulting from the higher spatial resolution and more comprehensive physical schemes." So, has the climate-model-tweaking enterprise lived up to this expectation?

In an effort to answer this question, "extensive integrations under phase 5 of the Coupled Model Intercomparison Project (CMIP5) historical scenarios from 15 CGCMs and Atmospheric Model Intercomparison Project (AMIP) runs from eight atmospheric general circulation models (AGCMs)" were used by Duan et al. "to evaluate the performance of these GCMs," focusing on "the climatology, annual cycle, inter-annual variability, and trend of the TPSM [Tibetan Plateau summer monsoon]." Based on their evaluation the three Chinese researchers report that (1) "the large bias associated with precipitation [a] intensity and [b] patterns remains," that (2) "regarding long-term trends, most models overestimated [c] the amplitude of the tropospheric warming and [d] the declining trend in the surface heat low between 1979 and 2005," and that (3) "the observed cooling trend in the upper troposphere and [4] the decline of the Tibetan high were not reproduced by most models."

In the parting words of Duan et al., as expressed in the concluding sentence of their paper's abstract, "there is still significant scope for improving GCM simulations of regional climate change." But with so little improvement over the prior seven years, a significant advancement may still not be realized any time soon.

Additional Reference
Zhou, T.J. and Yu, R.C. 2006. Twentieth-century surface air temperature over China and the globe simulated by coupled climate models. Journal of Climate 19: 5843-5858.

Archived 22 January 2014