区域气候模式水平分辨率对黄淮海流域当代气候模拟的影响

Role of horizontal resolution in regional climate simulations over the Huang-Huai-Hai River basin

区域气候模式是进行流域尺度气候变化研究的重要工具,其中水平分辨率对流域模拟结果的影响亟待评估。本文使用区域气候模式RegCM4,在ERA-Interim再分析资料驱动下,进行2种水平分辨率(50 km和25 km)1990—2010年东亚区域的长时间连续积分模拟。通过与观测资料的对比,评估RegCM4对黄淮海流域的模拟性能,同时分析水平分辨率对模拟结果的影响。结果表明:①2组模拟均可以较好地再现黄淮海流域冬季、夏季平均气温和降水的空间分布,以及气温和降水的年循环变化;对极端气候事件指数的分布模拟效果也较好,且对与气温有关的极端气候事件指数模拟效果优于与降水有关的极端气候事件指数。②与观测相比,也存在一定的偏差,如模拟的冬季气温存在冷偏差,夏季气温存在暖偏差,冬季、夏季降水在大部分地区偏多等。③2组模拟对比来看,对冬季、夏季平均气温的量级和空间分布,25 km模拟与观测更加接近;对冬季、夏季平均降水,50 km模拟与观测的空间相关系数分别为0.86和0.44,较25 km模拟有较大提高;对极端事件,2组模拟差别不大。模拟结果可为后续此版本模式在黄淮海流域气候变化研究中的应用提供参考。

As a primary tool in climate change research at the watershed scale,the role of horizontal resolution in regional climate simulations needs to be evaluated.This paper investigates the role over the Huang-Huai-Hai(HHH)River basin using a regional climate model,RegCM4,coupled with the National Center for Atmospheric Research(NCAR)Community Land Model,version 4.5(CLM4.5)including the modules of CN and DV(RCM_CLM4.5).The model is driven by ERA-Interim reanalysis data,and the time period is 1990—2010.Model validation shows that RCM_CLM4.5 at 50 km and 25 km resolutions can reproduce the present climate well,including the spatial distribution of winter and summer mean temperature and precipitation,the annual cycles of temperature and precipitation,and the climate extremes.However,some biases can also be found.For example,compared with the observation,cold and warm biases are found in the winter and summer mean temperature,respectively;wet biases are found in the precipitation.Comparison between the two simulations,better performance of the magnitude and spatial distribution of mean temperature is found in the simulation at 25 km resolution;while for precipitation,better performance is observed in the one at 50 km resolution;little difference is found for the climate extremes.In general,results from this study indicate a very low sensitivity of present climate in this region to model resolution and can provide a reference for the application of this model in future climate change research over the HHH River basin.