Abstract. 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.
Assimilating Coherent Doppler Lidar Measurements into a Model of the Atmospheric Boundary Layer. Part I: Algorithm Development and Sensitivity to Measurement Error
