南极探空与两套再分析资料的对比分析

基于南极18个站点探空气象观测数据对欧洲中期天气预报中心的再分析数据(ERA-Interim)和美国国家环境预报中心的再分析数据(NECP)在南极地区高层大气的适用性进行验证。结果表明:在南极上空,随着高度抬升,探空气象观测数据与两套再分析数据中四个气象要素的差值均逐渐变大,再分析数据数值愈加偏离实际观测数值。两套再分析数据的位势高度和温度与探空观测数据偏差较小;风向则和探空观测数据相差甚远;两套再分析数据的风速与探空观测数据在300 hPa偏差较大。在季节变化中,南极的春季,再分析数据中的位势高度和温度与探空观测数据相差较大,在其他季节相差相对较小。再分析数据中的风速与探空观测数据在南极的夏季相差较小。再分析数据中的风向与探空观测数据存在较大偏差,且差值没有明显的季节变化。尽管两套再分析数据都存在很大偏差,但ERA-Interim数据整体上优于NCEP数据。对比分析也表明,采用这些再分析资料作为初始条件和边界条件驱动南极区域大气模式将带来较大的误差。未来需要加强南极探空观测,改进再分析资料同化和数值模拟系统。

A comparison analysis of Antarctic radiosonde data with two sets of reanalysis data

This study analyzed the ERA-Interim data from the European Centre for Medium-Range Weather Forecasts and NECP reanalysis data from the National Oceanic and Atmospheric Administration Earth System Research Laboratory in the Antarctic region to compare with the radiosonde data derived from the Antarctic 18 stations, assessed the applicability of these two reanalysis data sets in the upper atmosphere.The results demonstrated that the reanalysis data sequentially drift away from the radiosonde data steadily in four meteorological elements with the increase in height over the Antarctic.The biases in geopotential height and temperature in the two reanalysis data are relatively small,but the differences of wind direction between the sounding data and the two sets of reanalysis data are quite huge.The differences in wind speed between the sounding data and the two sets of reanalysis data are quite large at 300 hPa.In the seasonal distributions of these biases,the differences of the geopotential height and temperature between the sounding data and the two sets of reanalysis data are huge in the austral spring but are relatively small in autumn,summer,and winter.The difference in the wind speed between the sounding data and the two sets of reanalysis data is relatively small in summer.The difference of the wind direction between the sounding data and the two sets of reanalysis data is relatively large but has no significant seasonal dependency.Nevertheless,both reanalysis data sets have large biases,ERA-Interim performs better than NCEP as a whole.The results suggest that using the data from these two reanalysis data sets as initial and boundary conditions to drive regional atmospheric models can lead to large model biases.Thus,more intensive radiosonde observations are necessitated for improving the qualities of reanalysis data,along with further improvements in the data assimilation and model system.