摘要:本文利用中国科学院大气物理研究所地球系统模式CAS-ESM和NCAR CESM中的气候系统模式开展了一系列不同物理参数化方案和水平分辨率的模拟试验，并针对欧亚大陆逐日降水特征模拟性能进行分析研究。本研究进行了四组时长为19年（1998～2016年）的AMIP（Atmospheric Model Intercomparison Project）数值积分试验：在1.9°×2.5°的低分辨率下NCAR CESM模式使用CAM5物理参数化方案组合（记为CESM），在1.4°×1.4°的低水平分辨率下CAS-ESM模式使用CAM4与CAM5两种不同物理参数化方案组合（依次记为Lcam4和Lcam5），在0.5°×0.5°的高水平分辨率下CAS-ESM模式使用CAM5物理参数化方案（记为Hcam5）。通过与GPCC（Global Precipitation Climatology Centre）、CMORPH（CPC MORPHing technique）观测资料比较，两个模式较好地再现了平均降水特征和极端降水的气候态，但模式的降水频率偏大、降水强度偏弱。CESM的大雨日数与观测较为接近，Hcam5模拟的日最大降水量与观测最接近。针对CAS-ESM模式，不同物理参数化方案和水平分辨率均对降水特征产生影响，其中提高分辨率对降水特征的模拟有显著的改进。Lcam4和Lcam5相比，Hcam5显著提高了极端降水的模拟性能。在欧亚大陆中高纬地区，Lcam4的降水频率高于Lcam5；而在中国东部，Hcam5的降水频率比Lcam5小，与GPCC偏差更小。进一步分析的结果表明，与Lcam5相比，在欧洲地区Lcam4中的大尺度降水较多，水汽输送更强。在中国东部，Hcam5中对流性降水频率比Lcam5更小，而大尺度降水和水汽输送更大，使得高分辨率的模拟试验性能提高。
关键词:地球系统模式/
欧亚大陆/
逐日降水特征/
极端降水
Abstract:In this paper, two earth system models, i.e., CAS-ESM (Earth System Model, Chinese Academy of Sciences) and NCAR CESM (Community Earth System Model, National Center for Atmospheric Research), are used to carry out a series of simulations with different parameterizations and horizontal resolutions, and the daily precipitation characteristics of Eurasia are analyzed. Four 19-year (1998–2016) Atmospheric Model Intercomparison Project simulations have been conducted in this study. They included CESM with the Community Atmosphere Model version 5 (CAM5) physics package at a resolution of 1.9°×2.5°, CAS-ESM with the CAM4 (Lcam4) and CAM5 (Lcam5) packages at a resolution of 1.4°×1.4°, and CAS-ESM with the CAM5 package at a resolution of 0.5°×0.5° (Hcam5). Compared with GPCC (Global Precipitation Climatology Centre) and CMORPH (CPC MORPHing technique), both models competently reproduced the climatological means of precipitation and extreme precipitation. However, the two models overestimated precipitation frequency and underestimated precipitation intensity. CESM produced the smallest biases in the number of heavy rain days, and Hcam5 showed added value for maximum daily precipitation. For CAS-ESM, both the physics package and horizontal resolutions impacted daily precipitation characteristics. Noticeable improvements in precipitation characteristics were demonstrated by Hcam5. The precipitation frequency of Lcam4 was higher than that of Lcam5 in the middle and high latitudes of Eurasia. Over eastern China, the biases of precipitation frequency for Hcam5 were smaller than those of Lcam5, and the high-resolution model distinctly improved the simulation of extreme precipitation. Further, compared with Lcam5, Lcam4 produced more large-scale precipitation and stronger water vapor fluxes over Europe. Over eastern China, improvements in daily precipitation frequency and extreme precipitation related to the reduction in convective precipitation frequency, greater large-scale rainfall, and stronger water vapor fluxes.
Key words:Earth system model/
Eurasia/
Daily precipitation characteristics/
Extreme precipitation
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