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The parameterization of physical processes is one of the critical elements to properly simulate the regional climate over eastern China. It is essential to conduct detailed analyses on the effect of physical parameterization schemes on regional climate simulation, to provide more reliable regional climate change information. In this paper, we evaluate the 25-year (1983-2007) summer monsoon climate characteristics of precipitation and surface air temperature by using the regional spectral model (RSM) with different physical schemes. The ensemble results using the reliability ensemble averaging (REA) method are also assessed. The result shows that the RSM model has the capacity to reproduce the spatial patterns, the variations, and the temporal tendency of surface air temperature and precipitation over eastern China. And it tends to predict better climatology characteristics over the Yangtze River basin and the South China. The impact of different physical schemes on RSM simulations is also investigated. Generally, the CLD3 cloud water prediction scheme tends to produce larger precipitation because of its overestimation of the low-level moisture. The systematic biases derived from the KF2 cumulus scheme are larger than those from the RAS scheme. The scale-selective bias correction (SSBC) method improves the simulation of the temporal and spatial characteristics of surface air temperature and precipitation and advances the circulation simulation capacity. The REA ensemble results show significant improvement in simulating temperature and precipitation distribution, which have much higher correlation coefficient and lower root mean square error. The REA result of selected experiments is better than that of nonselected experiments, indicating the necessity of choosing better ensemble samples for ensemble. [ABSTRACT FROM AUTHOR]

The Meiyu/Baiu/Changma is an important and unique persistent rainfall over East Asian during the northward progress of the East Asian summer monsoon (EASM) from late spring to middle summer. In this study, changes of Meiyu system under global warming are examined by MIROC_Hires coupled model. The results reveal that the Meiyu system becomes weaker in the warmer future: the large precipitation center shifts to northern China; ratio of Meiyu rainfall to total summer precipitation ratio decreases. For the three-dimensional atmospheric circulation, the configuration of upper and lower jets benefits the heavy rainfall located over the northern China, associated with abundant water vapor transporting to northern China. The heterogeneous warming over land and sea may be a possible reason for the changes of Meiyu system. Larger thermal contrast is indicated between the Asian continent and the western Pacific during the Meiyu period, which may result in the enhanced southerly with abundant water vapor arriving at northern China. Therefore, rainfall over Meiyu region may be suspended. [ABSTRACT FROM AUTHOR]