[Model development, algorithm, and evaluation] Scientists find the effect of horizontal resolution on the representation of the global monsoon annual cycle in AGCMs

Annual cycle is the main characteristic of global monsoon system. It is crucial for the drought/flood management in monsoon region. The complexity of monsoon systems presents great challenges in simulating the climatological seasonal means and annual cycles of the monsoon. The increase of the horizontal resolution is proposed to be as one of the useful techniques to improve monsoon simulation. Given the social and scientific importance of the onset and cessation of monsoon precipitation to local livelihoods and economies, it is desirable to find out whether high resolution systematically improves the representation of monsoon onset and withdrawal.

Under the Climate Science for Service Partnership: China (CSSP-China)，scientists from the Institute of Atmospheric Physics, Chinese Academy of Sciences, University of Reading and Met Office Hadley Centre compared the results of three AGCMs. The results show that increasing resolution consistently improves simulated precipitation and low-level circulation of the annual mean and the first two annual cycle modes (Fig.1). Improvements in simulating the summer monsoon onset and withdrawal are region-dependent. Higher resolution models consistently improve the early summer monsoon onset over East Asia and West Africa. “It is important to make a multi-model comparison when examining the added value of resolution, and model physical parameterizations are still crucial for monsoon simulation.” Said Lixia Zhang, the first author of this paper recently published in Advances in Atmospheric Sciences.

Fig.1 Improvement in the simulation of the annual cycle of global monsoon precipitation with horizontal resolution. Red boxes indicate high-resolution consistently improves performance across all three AGCMs; blue boxes indicate improvements with resolution are inconsistent; orange boxes indicate a better simulation is shown in all three high-resolution AGCMs but the responses to resolution are inconsistent across models.

Citation:

Lixia ZHANG, Tianjun ZHOU, Nicholas P. KLINGAMAN, et al. 2018. Effect of Horizontal Resolution on the Representation of the Global Monsoon Annual Cycle in AGCMs. Adv. Atmos. Sci., 10.1007/s00376-018-7273-9