Investigation of nocturnal low-level jet–generated gravity waves over Oklahoma City during morning boundary layer transition period using Doppler wind lidar data

Abstract

Abstract. Low-level jet (LLJ)-generated gravity waves were observed over Oklahoma City by a scanning Doppler wind lidar during the transition periods of atmospheric boundary layer (ABL) from stable to convective conditions in the mornings after sunrise. The temperature profiles had a multilayer structure with a shallow neutral layer immediately above the ground and a stable cap layer above the neutral layer. The wind profiles exhibited a typical shape of a LLJ with nearly linear growth of wind speed with respect to height, and maximum wind speed occurred at the top of the stable cap layer. The average wavelength and its relation with mean wind and temperature profiles are characterized with data from Doppler wind lidar, radiosonde, and wind profiler. A linear stability analysis was performed to check the stratification conditions for wave occurrence. The wind signals from sonic anemometers near the ground were separated into waves and turbulence parts using a wavelet decomposition method, and the momentum fluxes due to the wave motions and turbulence were computed. The downward gravity wave momentum flux was 1.5 to 3.0 times of turbulent momentum flux. The analysis indicated that gravity wave momentum transport from the stable cap layer downward is one of the mechanisms of stable-to-convective transition in the LLJ-dominated ABL.

Nocturnal low-level clouds over southern West Africa analysed using high-resolution simulations

“…under conditions in which gravity waves are common features (e.g. Fritts et al, 2003;Newsom and Banta, 2003;Wang et al, 2013). Besides vertical wind shear, some of the gravity waves seem to be linked to orographic features, although obstacle heights upstream of SAVE are on the order of 50 m only.…”

Triple Doppler wind lidar observations during the mountain terrain atmospheric modeling and observations field campaign

“…Single DWLs have been extensively used in ABL studies for both flat and gently variable terrain, [13][14][15][16][17][18][19] over urban areas, [20][21][22][23] and for studies on wind turbine wakes at heights of hundreds of meters. 24 While the assumptions used for single DWL retrievals are appropriate for many situations, they are not suitable for highly complex and spatially variable turbulent flows in mountainous terrain.…”

Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere on the coast of Lake Baikal

“…For studying AGW, coherent Doppler wind lidars (CDWLs) and sodars are used as well. Newsom and Banta (2003) and Wang et al (2013) applied 2 µm CDWL to investigate of low-level jet and gravity waves in the stable ABL over flat and urban terrains, respectively. Lyulyukin et al (2015) observed AGW in the lower atmospheric layer (300-400 m) based on sodar data.…”