Abstract. The weak-wind Stable Boundary Layer (wwSBL) is poorly described by theory and breaks basic assumptions necessary for observations of turbulence. Understanding the wwSBL requires distributed observations capable of separating between submeso and turbulent scales. To this end, we present the Large Eddy Observatory, Voitsumra Experiment 2019 (LOVE19) which featured 1350 m of fiber optic distributed sensing (FODS) of air temperature and wind speed, as well as an experimental wind direction method, at scales as fine as 1 s and 0.127 m in addition to a suite of point observations of turbulence and ground-based remote sensing. Additionally, flights with a fiber optic cable attached to a tethered balloon provide an unprecedented detailed view of the boundary layer structure with a resolution of 0.254 m and 10 s between 1–200 m height. Two examples are provided demonstrating the unique capabilities of the LOVE19 data for examining boundary layer processes: 1) FODS observations between 1m and ~200 m height during a period of gravity waves propagating across the entire boundary layer and 2) tracking a near-surface, transient submeso structure that causes an intermittent burst of turbulence. All data can be accessed at Zenodo through the DOI https://doi.org/10.5281/zenodo.4312976 (Lapo et al., 2020a).

Abstract. The weak-wind stable boundary layer (wwSBL) is poorly described by theory and breaks basic assumptions necessary for observations of turbulence. Understanding the wwSBL requires distributed observations capable of separating between sub-mesoscales and turbulent scales. To this end, we present the Large eddy Observatory, Voitsumra Experiment 2019 (LOVE19) which featured 2105 m of fiber-optic distributed sensing (FODS) of air temperature and wind speed, as well as an experimental wind direction method, at scales as fine as 1 s and 0.127 m in addition to a suite of point observations of turbulence and ground-based remote sensing profiling. Additionally, flights with a fiber-optic cable attached to a tethered balloon (termed FlyFOX, Flying Fiber Optics eXperiment) provide an unprecedentedly detailed view of the boundary layer structure with a resolution of 0.254 m and 10 s between 1 and 200 m height. Two examples are provided, demonstrating the unique capabilities of the LOVE19 data for examining boundary layer processes: (1) FODS observations between 1 and 200 m height during a period of gravity waves propagating across the entire boundary layer and (2) tracking a near-surface, transient, sub-mesoscale structure that causes an intermittent burst of turbulence. All data can be accessed at Zenodo through the DOI https://doi.org/10.5281/zenodo.4312976 (Lapo et al., 2020a).

In the morning, the nocturnal stable boundary layer, SBL, transitions into its daytime convective counterpart substantially impacting the distribution of temperature, humidity, and pollutants. Applying distributed temperature sensing (DTS) below a tethered balloon (2–200 m) and along a tower (0–11 m), for the first time we observed three morning transitions (MTs) in a mountain boundary layer with high temporal (<10 s) and spatial (<0.25 m) resolutions. We show that MTs are best derived from a change in static stability from synchronous DTS observations. Our findings confirm that the MT occurs at the SBL top and bottom simultaneously, and identify horizontal heat advection as a main driver aiding solar surface heating in this midrange mountain valley. We conclude that heterogenous land use and mountainous topography cause complex interactions between valley‐scale and local airflows leading to thermal signatures characterized by strong, small‐scale variability. Our study highlights DTS as a crucial tool for investigating complex thermodynamic processes.

No abstract

No abstract