一组RegCM4动力降尺度对中国群发性高温事件的模拟评估

基于高分辨率格点数据集CN05.1和区域气候模式RegCM4对4个全球气候模式动力降尺度模拟（CdR、EdR、HdR、MdR）,识别了观测和模拟的1981—2005年中国群发性高温事件（CHTE）。在此基础上,评估了模式对中国CHTE的模拟能力。结果表明：4个动力降尺度模拟以及多模式集合（MME）均能很好地模拟出中国CHTE频次、持续时间和累计强度的空间分布。不过,HdR模拟的CHTE发生次数在新疆地区略偏少,而其他3个模拟试验的CHTE次数在中国东南部略偏多。观测中CHTE持续时间、极端强度、累计强度、最大影响面积、平均影响面积、综合强度等的频率分布规律均能被合理再现。MME也能很好模拟观测揭示的CHTE综合强度以及频次、持续时间、强度、影响面积等单项指标的上升趋势。单模式成员亦可再现大多数指标的上升趋势,但也存在一定不足,如EdR模拟的CHTE综合强度呈减弱趋势,MdR模拟的CHTE频次和极端强度呈弱的下降趋势。

Evaluation of multi-RegCM4 dynamical downscaling simulations on cluster high temperature events in China

Based on the high-resolution grid observation dataset CN05.1 and the regional climate model RegCM4 dynamical downscaling simulations (i.e., CdR, EdR, HdR, and MdR), the cluster high temperature events (CHTE) occurring in China during 1981-2005 were identified using a simplified objective method. Then, the performance of the RegCM4 dynamical downscaling simulations on the CHTE in China was evaluated through the comparison with the observation. The results indicate that the four RegCM4 simulations and their ensemble mean (MME) can reproduce the observed climatological distribution of the frequency, duration and cumulative intensity of the CHTE in China. However, the frequency of the CHTE in Xinjiang is slightly underestimated by the HdR simulation while that in southeastern China is slightly overestimated by the CdR, EdR and MdR simulations. The characteristics of the probability in duration, extreme intensity, cumulative intensity, maximum influential area, average influential area, and comprehensive intensity for the CHTE can also be reasonably captured by the MME and its ensemble members. In addition, the MME simulates an upward trend, which is consistent with the observation, in the comprehensive intensity index and the individual indices of the CHTE in China. The individual simulations can also reproduce the upward trend for most of the indices. However, some deficits are also found. For instance, the EdR simulation produces a downward trend for the comprehensive intensity of the CHTE, and the MdR simulation shows a weak downward trend for the frequency and extreme intensity of the CHTE.