中国中东部地区再分析资料地面温度误差周期性特征分析

Analysis on the Periodic Characteristics of Ground Temperature Error in Reanalysis Data in Central and Eastern China

地面温度是表征大气和陆地热力相互作用的重要变量,但是由于其强的小尺度变化特征,地面温度变化的分析一直受到观测资料时空密度的制约。利用2019年1月和7月我国高时空分辨率的自动站观测资料,分析了GFS(Global Forecast System)和ERA5(European Centre for Medium-range Weather Forecasts fifth reanalysis data)两种再分析资料对中国东部地区地面温度变化特征的再现能力。结果表明:两种再分析资料的地面2 m温度和地表温度均有明显的日变化特征,但是观测资料与再分析资料的差值出现了明显的规律性特征。进一步分析表明差值的规律性主要是由于两种再分析资料对我国地面温度日变化的周期特征的模拟存在系统性位相偏差,而且位相偏差还存在明显的经度依赖性,通过对各经度带误差特征的定量分析,论文初步探讨了规律性误差形成的可能原因。

Ground temperature is an important variable affecting the thermal interaction between atmosphere and land.However,due to its strong small-scale variation characteristics,the study of ground temperature variation has been restricted by the insufficient spatial and temporal resolution of the observations.Based on the observation data of automatic stations with high spatial-temporal resolution in China in January and July 2019,the reproduction ability of two reanalysis data,GFS(Global Forecast System)and era5(European Center for medium range weather forecasts fifth reanalysis data),to the variation characteristics of ground temperature in eastern China is analyzed.The results show that the surface 2m temperature and ground temperature of the two reanalysis data have obvious diurnal variation characteristics,but the difference between the observation and the reanalysis data has obvious diurnal characteristics.Further analysis shows that the diurnal characteristics of the difference is mainly due to the systematic phase bias of the two reanalysis data in the simulation of the diurnal variation of ground temperature in China,and the phase bias also has an obvious longitude dependence.The possible causes of the diurnal variation of the errors are also discussed by comparative analysis of the errors in each latitude band.