中国东部及西北太平洋地区边界层高度变化特征

Variation Characteristics of the Atmospheric Boundary Layer Height in Eastern China and Northwest Pacific

利用19792019年ERA5逐月大气边界层高度(ABLH,Atmospheric boundary layer height)资料,采用气候态分析、距平分析、极值分析、经验正交(EOF)分析及小波分析等方法,研究了中国东部及西北太平洋区域大气边界层高度的变化特征。结果表明:(1)太阳辐射对边界层高度有重要影响,边界层高度的季节变化存在显著的海陆差异,大陆(海洋)上,夏季时边界层高度最高(低),而在冬季时最低(高)。(2)边界层高度的海陆差异随季节改变,春秋季海陆差异较小,冬夏季时最明显。(3)大陆上边界层高度极大值出现在夏半年的月份,极小值出现在冬半年的月份;海洋上的相反。(4)41年边界层高度场的EOF分析得到两个模态,第一模态表现为南北经向和海陆差异,第二模态为自西北至东南的“+-+-”相位分布,第一模态的时间系数以3~7 a的周期最显著,第二模态同时存在4~7 a和9~11 a的振荡周期。

This paper investigates the atmospheric boundary layer height(ABLH)in eastern China and the northwest Pacific region using the ERA5 monthly ABLH data from 1979 to 2019,as well as the methods of climatological state analysis,anomaly analysis,extreme value analysis,Empirical Orthogonal Function(EOF),and wavelet analysis.The study results show that:(1)Solar radiation has an important impact on ABLH.There are significant differences between land and ocean in the seasonal changes of ABLH.The ABLH is the highest(lowest)on land(ocean)in summer,and are lowest(highest)in winter.(2)Land-ocean difference of boundary layer height varies with the changes of seasons,and the difference is smaller in spring and autumn,but significant in summer and winter.(3)The maximum value of the boundary layer height on land appears in the summer half year,while the minimum is in the winter half year.However,the situation over the ocean is opposite.(4)Two modes are obtained through studying the EOF analysis of 41-year boundary layer heights.The first mode is the north-south meridional difference and the land-sea difference,and the second mode has a“+-+-”distribution from northwest to southeast.The time coefficient of the first mode is most significant with a period of 37 years;and second mode has both oscillation periods of 47 years and 911 years.