Long-lived high-frequency gravity waves in the atmospheric boundary layer: observations and simulations

• Published in: Atmospheric chemistry and physics Vol. 19; no. 24; pp. 15431 - 15446
• Main Authors: Jia, Mingjiao, Yuan, Jinlong, Wang, Chong, Xia, Haiyun, Wu, Yunbin, Zhao, Lijie, Wei, Tianwen, Wu, Jianfei, Wang, Lu, Gu, Sheng-Yang, Liu, Liqun, Lu, Dachun, Chen, Rulong, Xue, Xianghui, Dou, Xiankang
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 17.12.2019; Copernicus Publications
• Subjects: Altitude; Analysis; Atmospheric boundary layer; Boundary layers; Computational fluid dynamics; Computer applications; Computer simulation; Doppler lidar; Doppler sonar; Ducts; Fluid dynamics; Gravitational waves; Gravity; Gravity waves; Hydrodynamics; Lidar; Low-level jets; Numerical analysis; Numerical simulations; Optical radar; Perturbations; Planetary boundary layer; Remote sensing; Wave generation; Wind; Wind shear; China
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-19-15431-2019

A long-lived gravity wave (GW) in the atmospheric boundary layer (ABL) is analysed during a field experiment in Anqing, China (30∘37′ N, 116∘58′ E). Persistent GWs with periods ranging from 10 to 30 min over 10 h in the ABL within a 2 km height are detected by a coherent Doppler lidar from 4 to 5 September 2018. The amplitudes of the vertical wind due to these GWs are approximately 0.15–0.2 m s−1. The lifetimes of these GWs are longer than 20 wave cycles. There is no apparent phase progression with altitude. The vertical and zonal perturbations in the GWs are 90∘ out of phase, with vertical perturbations generally leading to zonal ones. Based on experiments and simplified two-dimensional computational fluid dynamics (CFD) numerical simulations, a reasonable generation mechanism of this persistent wave is proposed. A westerly low-level jet of ∼5 m s−1 exists at an altitude of 1–2 km in the ABL. The wind shear around the low-level jet leads to wave generation under the condition of light horizontal wind. Furthermore, a combination of thermal and Doppler ducts occurs in the ABL. Thus, the ducted wave motions are trapped in the ABL and have long lifetimes.