黄土高原塬区近地面层重力波的辨识及其特征研究

Atmospheric Surface-layer Gravity Waves over the Loess Plateau:Observational Identification and Characterization

利用平凉陆面过程与灾害天气观测研究站2012年5-7月夜间近地面层观测资料,针对黄土高原塬区夜间不同风速和下垫面粗糙度条件,辨识塬区重力波,揭示重力波的频段,并对比研究了风速和粗糙度变化对该频段的影响。结果表明,平凉站塬区的夜间近地面层易于产生重力波,且即使整体Richardson远小于0.25时,也可以观测到重力波。受塬区下垫面特征影响,重力波的波动周期主要集中于60~110 s,同时随着观测高度的降低,重力波波动周期只存在10 s左右的变化。

To identify gravity waves,determine their frequency band and reveal the variation of frequency band caused by wind speed and roughness,observation of surface layer have been done at night from May to July in2012 at Pingliang Land Surface Process&Severe Weather Research Station.The results show that the tableland,where the observation station is located,is prone to cause gravity wave in surface layer under stable stratification conditions at night.Moreover,the gravity waves can be observed even when the total Richardson is way below0.25.Affected by the tableland,the fluctuation period of the gravity wave mainly focuses on 60~110 s.Meanwhile,with the decrease of the observation height,the fluctuation period of the gravity wave only varies for about 10 s.