2015年夏季那曲地区温度变化特征研究
Research on the Temperature Characteristics of Naqu Region in Summer 2015

基于2015年6~8月第三次青藏高原大气科学试验那曲地区的气温观测资料和ERA-5再分析资料，采用Morlet小波分析、Mann-Kendall突变检验和经验正交函数(Empirical Orthogonal Function, EOF)等方法，对青藏高原那曲地区夏季地面气温的时空变化特征进行了分析，结果表明：1) 不同高度气温日变化呈现出昼升夜降的特征，昼夜温差大；2) 日均温存在明显的季节内变化，6月升降温波动最大，其次是7和8月；3) 那曲地面气温存在2~7 d、8~13 d以及14~18 d三种尺度周期变化规律，其主周期为4 d；4) 2015年夏季那曲地面气温突变发生在6月20日，突变前气温呈显著降温趋势，突变后夏季气温呈显著升温趋势；5) ERA-5在那曲地区存在冷偏差，但其能再现地面气温的季节内变化；EOF分解显示高原夏季地面气温前四模态在空间上为全区一致型、东–西反相型、东到西“+？+”型和南北反相型，时间上则表现出震荡变化。
Based on observation of the third atmospheric science experiment on the Qinghai-Tibet Plateau and ERA-5 reanalysis data in August 2015, this paper analyzes the spatial and temporal changes of the summer ground temperature in Naqu region through Morlet wavelet analysis, Mann-Kendall test and Empirical Orthogonal Function. The results indicate that: 1) The daily temperature changes of different heights show the characteristics of day rise and night fall, with a large temperature difference between day and night; 2) The average daily temperature changes in obvious seasons, with the maximum temperature change in June, followed by July and August; 3) The ground temperature in Naqu has three scale cycle changes of 2 - 7 d, 8 - 13 d and 14 - 18 d, whose main period is 4 d; 4) In the summer of 2015, the ground temperature mutation in Naqu occurred on June 20, the mutation temperature showed a significant cooling trend, and the mutation summer temperature showed a significant warming trend; 5) ERA-5 has cold deviation in Naqu area, but it can reproduce the seasonal change of ground temperature; the first four modes of EOF decomposition show the ground temperature of plateau in space, east-west inversion, “+？+” and north-south inversion, and show shock change in time series.