Abstract:

The global climate model BCC-CSM2-MR (Beijing Climate Center-Climate System Model version 2-Medium Resolution) in⁃ dependently developed by the National (Beijing) Climate Center, which has participated in the Climate Model Interomparison Project Phase 6. Based on the BCC-CSM1.1m version, the BCC-CSM2-MR model is optimized in aspects of atmospheric radiation transport scheme, deep convection processes and gravity wave drag. Therefore, the improvement of the model’s ability to simulate precipitation and temperature in East Asia needs further assessment. Utilizing gridded observational datasets and station observations in China, the paper thoroughly compares the performances of BCC-CSM2-MR and BCC-CSM1.1m in simulating seasonal mean precipitation (tem⁃ perature) and daily precipitation (temperature) extremes in East Asia. The results are as follows: (1) Compared with the BCC-CSM1.1m, the BCC-CSM2-MR improves the model performance in simulating seasonal mean precipitation in most sub-regions of East Asia, espe⁃ cially for summer precipitation in the Tibetan Plateau. In particular, the model can better reproduce the annual cycle of precipitation in southeastern China, the Korean Peninsula and Japan. (2) The ability of the BCC-CSM2-MR to simulate the seasonal mean temperature in East Asia has not been improved significantly, and the simulated biases of monthly temperature change in most sub-regions of East Asia are greater than those of the BCC-CSM1.1m. (3) In terms of daily extreme precipitation (temperature), the simulation ability of the BCC-CSM2-MR is obviously better than that of the BCC-CSM1.1m, which significantly improves the simulation ability of daily extreme precipitation (temperature) in southeast China. Overall, the improvement of the BCC-CSM2-MR in deep convection process parameter scheme is beneficial to the simulation of precipitation in East Asia.

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摘要：

全球气候模式 BCC-CSM2-MR（Beijing Climate Center-Climate System Model version 2-Medium Resolution）由国家（北京）气候中心自主研发并参与了第六阶段国际耦合模式比较计划，该模式在 BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程及重力波等方面进行了优化，因此，该模式对 东亚地区降水和气温模拟能力的改进亟需进一步评估。本文主要基于不同格点观测数据集与中国区 域站点观测数据，系统对比分析BCC-CSM2-MR、BCC-CSM1.1m两个模式版本对东亚地区季节平均降 水（气温）和日极端降水（气温）的模拟能力。结果表明：（1）相比 BCC-CSM1.1m，BCC-CSM2-MR 改进 了对东亚大部分区域季节平均降水的模拟能力，尤其是青藏高原地区夏季平均降水，明显提高了对中 国东南地区、朝鲜半岛及日本降水月际变化的模拟性能；（2）BCC-CSM2-MR对东亚地区季节平均气温 模拟能力改进不明显，且对东亚大部分区域气温月际变化的模拟误差大于BCC-CSM1.1m；（3）对日极 端降水（气温），BCC-CSM2-MR的模拟能力优于BCC-CSM1.1m，明显提高了对中国东南地区日极端降 水（气温）的模拟能力。总体而言，BCC-CSM2-MR在深对流过程参数方案中的改进有利于对东亚地区 降水的模拟。

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