Abstract
Advancements in remotely piloted aircraft systems (RPAS) introduced a new way to observe the atmospheric boundary layer (ABL). Adequate sampling of the lower atmosphere is key to improving numerical weather models and understanding fine-scale processes. The ABL’s sensitivity to changes in surface fluxes leads to rapid changes in thermodynamic variables. This study proposes using low-level buoyancy to characterize ABL transitions. Previously, buoyancy has been used as a bulk parameter to quantify stability. Higher resolution data from RPAS highlight buoyancy fluctuations. RPAS profiles from two field campaigns are used to assess the evolution of buoyancy under convective and stable boundary layers. Data from these campaigns included challenging events to forecast accurately, such as convective initiation and a low-level jet. Throughout the daily ABL transition, results show that the ABL height determined by the minimum in vertical buoyancy gradient agrees well with proven ABL height metrics, such as potential temperature gradient maxima. Moreover, in the cases presented, low-level buoyancy rapidly increases prior to convective initiation and rapidly decreases prior to the onset of a low-level jet. Low-level buoyancy is a function sensitive in space and time, and with further analysis could be used as a forecasting tool. This study expounds on the utility of buoyancy in the ABL and offers potential uses for future research.
Highlights
The atmospheric boundary layer (ABL) is strongly influenced by kinematic and thermodynamic interactions with the Earth’s 15 surface
Throughout the daily ABL transition, results show that the ABL height determined by the minimum in vertical buoyancy gradient agrees well with proven ABL height metrics, such as potential temperature gradient maxima
275 This study uses buoyancy measured from remotely piloted aircraft systems (RPAS) to describe transitions within the ABL
Summary
The atmospheric boundary layer (ABL) is strongly influenced by kinematic and thermodynamic interactions with the Earth’s 15 surface. The depth of the ABL (referred to as ABL height) and the ABL stability fluctuate in time and space (Lenschow et al, 1979; Stull, 1988). This influences local weather (Lapworth, 2006), turbulence (Banta et al, 2003; Bonin et al, 2013), and aerosol transport (Nilsson et al, 2001; De Wekker et al, 2009; Pal et al, 2014). The best choice for boundary layer parameterizations is situationally dependent to what is being modeled (Braun and Tao, 2000; Nolan et al, 2009; Hu et al, 2010; Cuchiara et al, 2014; Cohen et al, 2015).
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