风廓线雷达C^(2)_(n)资料和L探空资料确定济南夏季边界层高度的对比研究

Comparison Study of Wind Profile Radar C^(2)_(n)Data and L Sounding Data to Determine the Height of Summer Boundary Layer in Ji’nan

基于济南站边界层风廓线雷达(WPR)观测的大气折射率结构常数(C^(2)_(n)),采用偏离度法确定夏季白天的对流边界层高度(HCBL),并与L探空虚位温梯度法、L探空湿度梯度法的结果进行对比。结果表明:(1)WPR偏离度法判别的HCBL成功率高,07、13、19时分别可达96.9%、100.0%、89.3%,尤其19时的判别成功率远高于L探空两方法的46.4%、57.1%。(2)WPR偏离度法与L探空两方法判别的同时刻HCBL结果一致性好,相关系数高。07时WPR判别的边界层高度平均值分别较后两者的差+14.3、+9.3 m,13时的差+36.4、+21.6 m,19时的差-27.3、-25.4 m;与后两者的标准偏差,07时的分别为84.555、77.412 m,13时的分别为125.978、126.783 m,19时的分别为52.743、68.755 m;与后两者的相关系数,07时的分别为0.894、0.911,13时的均为0.980,19时的分别为0.980、0.969。WPR能够将夏季HCBL确定结果的绝对误差降至近似其垂直分辨率水平。(3)济南6、7月逐小时HCBL最高可达3460.0、3220.0 m,小时平均最高分别为2205.0、2157.1 m;逐小时最高值在1316时均可出现,且以15时的最多;通常0715时的HCBL呈波浪起伏式缓慢增高态势,1519时的HCBL则是断崖式快速降低。

Based on the atmospheric refractive index structure constant(C^(2)_(n))observed by the boundary layer wind profile radar(WPR)at Ji’nan Station,the convective boundary layer height(HCBL)during summer days is determined by the WPR deviation method.Then,the result is compared with the results of the L sounding virtual potential temperature gradient method and the L sounding humidity gradient method.The results show that:(1)The success rate of HCBL determination by the WPR deviation method is relatively high,which can reach 96.9%,100.0%,and 89.3%at 07:00,13:00,and 19:00(Beijing Time)respectively,and especially at 19:00,the value 89.3%is much higher than 46.4%and 57.1%of the other two methods.(2)The HCBL results determined by the WPR deviation method and the two L sounding methods at the same time have good consistency and high correlation coefficients.The mean height of the boundary layer determined by the WPR deviation method is different from the means by the two L sounding methods with+14.3,+9.3 m at 07:00,+36.4 m,+21.6 m at 13:00,and-27.3 m,-25.4 m at 19:00,respectively.The standard deviations of the result by the WPR deviation method and the results by the two L sounding methods are 84.555 m and 77.412 m at 07:00,125.978 m and 126.783 m at 13:00 and 52.743 m and 68.755 m at 19:00,respectively.And the corrleation coefficicnets between the values by the WPR deviation method and the two L sounding methods are 0.894 and 0.911 at 7:00,0.980 and 0.980 at 13:00,0.980 and 0.969 at 19:00.The WPR deviation method can reduce the absolute error of summer HCBL determination results to approximately its vertical resolution level.(3)In June and July,the hourly HCBL can reach 3460.0 m and 3220.0 m,appearing from 13:00 to 16:00 and the highest value is often at 15:00.The hourly average value can reach 2205.0m and 2157.1 m,respectively.Generally,the HCBL from 07:00 to 15:00 is undulating and slowly increasing,while the HCBL from 15:00 to 19:00 tends to decline sharply.