Near-Surface Motion in the Nocturnal, Stable Boundary Layer Observed with Fibre-Optic Distributed Temperature Sensing

Abstract

The evolution of cold air layers near the surface was investigated for a night with stable conditions near the surface. Spatial air temperature observations at 276 co-located vertical profiles were made using high-resolution fibre-optic based distributed temperature sensing (DTS) in a quasi three-dimensional geometry oriented along a shallow depression in the landscape and analysed for patterns in near-surface flow. Temperature stratification was observed to be interrupted by transient temperature structures on the scale of metres for which the flow direction and velocity could be quantified. The high spatial resolution and large spatial domain of the DTS revealed temperature structures in a level of detail that exceeded the capability of traditional point observations of air temperature at low wind speeds. Further, composition techniques were applied to describe wave-like motions in the opposite direction of the mean flow, at intervals of approximately 200 s (5 mHz). The DTS technique delivered tomography on a scale of tens of metres. The spatial observations at high spatial (fractions of a metre) and temporal (sec) resolution provided new opportunities for detection and quantification of surface-flow features and description of complicated scale interactions. High-resolution DTS is therefore a valuable addition to experimental research on stable and weak-wind boundary layers near the surface.

Internal waves influence the thermal and nutrient environment on a shallow coral reef

“…In DTS, a coherent pulse of light is sent down the cable, and continuous measurements of Raman backscattered light spectra allows for determination of the temperature at each point in the cable (Tyler et al ; Hausner et al ). DTS technology has been used in various environmental monitoring programs in the past, providing high spatial (< 1 m) resolution temperature measurements at scales of meters to kilometers (Selker et al ; Tyler et al ; Hausner et al ; Suárez et al ; Vercauteren et al ; Van Emmerik et al ; Kobs et al ; Zeeman et al ).…”

Failure of Taylor's hypothesis in the atmospheric surface layer and its correction for eddy‐covariance measurements

“…Commercial instruments can obtain temperature continuously at resolution of 0.01°C, every meter, over distances of up to 10,000 m [Selker et al, 2006a]. It has also been useful in the atmospheric boundary to investigate turbulent structures [Sayde et al, 2015;Thomas et al, 2011;Zeeman et al, 2015]. It has also been useful in the atmospheric boundary to investigate turbulent structures [Sayde et al, 2015;Thomas et al, 2011;Zeeman et al, 2015].…”

High‐resolution wind speed measurements using actively heated fiber optics

“…[] and Zeeman et al . [] have demonstrated that this technology can be used to observe air temperature and thermal structure of near‐surface turbulence.…”

“…The ability of DTS to report temperature at such resolution has opened up many opportunities in environmental monitoring [e.g., Selker et al, 2006aSelker et al, , 2006bTyler et al, 2008Tyler et al, , 2009Steele-Dunne et al, 2010] including applications in the atmosphere [Keller et al, 2011;Petrides et al, 2011]. Recently, Thomas et al [2012] and Zeeman et al [2015] have demonstrated that this technology can be used to observe air temperature and thermal structure of near-surface turbulence. • Text S1 and S2, Figures S1-S4, Table S1, and Movie S1 Caption • Movie S1…”