Dynamical downscaling simulation of the East Asian summer monsoon in a regional Climate‐Weather Research and Forecasting model
Dynamical downscaling simulation of the East Asian summer monsoon in a regional Climate‐Weather Research and Forecasting model
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DOI：
10.1002/joc.6800
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
Qingquan Li;Tao Wang;Fang Wang;Xinyi Liang;Chongbo Zhao;Lili Dong;Chunyu Zhao;B. Xie
中科院分区：
文献类型：
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作者：
Qingquan Li;Tao Wang;Fang Wang;Xinyi Liang;Chongbo Zhao;Lili Dong;Chunyu Zhao;B. Xie
利用水平分辨率为30 km的区域气候-天气研究与预报模式（CWRF）对1980 - 2016年东亚夏季风（EASM）和中国气候进行了模拟。与观测资料和再分析资料的比较表明，模式能较好地模拟东亚地区气候平均大气环流和水汽输送的空间分布，以及东亚夏季风和雨带的季节进退。模拟结果与再分析结果的相关系数为0.97。该模式能较好地反映我国大部分地区夏季平均气温和降水的地理分布。但模型偏差仍然存在，特别是在江淮流域的技能相对较低。模拟的气候平均温度和降水与观测值的偏差可能与模式的系统性环流偏差有关，对流层下部较厚（即，夏季，我国大部分地区（除南部和西南部外）气温偏高（500 ~ 1000 hPa），沿海地区气温偏低。与再分析结果相比，模式高估了海陆热力对比，导致南亚高压北移和东移，副热带高压和热带对流活动位置偏北，持续时间较长。因此，更多的水汽向北输送，导致华北-东北地区降水偏多，而长江和淮河流域降水偏少。因此，增强的海陆热力对比可能是导致模式中东亚夏季风偏强以及中国降水和温度偏差的主要因素。这一分析为进一步提高EASM模拟的模型性能提供了重要信息。
A regional Climate‐Weather Research and Forecasting (CWRF) model with a 30‐km horizontal resolution was applied to simulate the East Asian summer monsoon (EASM) and climate in China from 1980 to 2016. As compared with observations and reanalysis data, the model can reasonably reproduce the spatial distributions of the climatological mean atmospheric circulation and water vapour transport in East Asia, as well as the seasonal advance and retreat of EASM and rain bands. The correlation coefficient between the EASM circulation index in the simulation and reanalysis is .97. The model can well represent the geographic distributions of summer mean temperature and precipitation over most of China. However, model biases still exist, in particular the skill in the Yangtze–Huaihe River basin is relatively low. The simulated climatological mean temperature and precipitation deviations from observations may be related to the model's systematic circulation biases, with a thicker lower troposphere (i.e., higher temperature between 500 and 1,000 hPa) over most of China (except for the south and southwest) and a thinner one over the coastal oceans in summertime. Compared with the reanalysis, the model overestimates the land‐ocean thermal contrast, which causes the South Asian High shifted to the north and east, as well as the subtropical high and tropical convective activity located further north and persisted longer. Consequently, more water vapour transports northward, leading to more precipitation over North China–Northeast China and less precipitation over the Yangtze and Huaihe River basin. Therefore, the enhanced land‐ocean thermal contrast may be a major factor for the stronger EASM in the model, and corresponding precipitation and temperature biases in China. This analysis provides important information for further improving model performance in EASM simulation.