Suitability of fibre-optic distributed temperature sensing for revealing mixing processes and higher-order moments at the forest–air interface
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Published:2021-03-26
Issue:3
Volume:14
Page:2409-2427
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ISSN:1867-8548
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Container-title:Atmospheric Measurement Techniques
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language:en
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Short-container-title:Atmos. Meas. Tech.
Author:
Peltola OlliORCID, Lapo KarlORCID, Martinkauppi Ilkka, O'Connor EwanORCID, Thomas Christoph K.ORCID, Vesala Timo
Abstract
Abstract. The suitability of a fibre-optic distributed temperature sensing (DTS) technique for observing atmospheric mixing profiles within and above a forest was quantified, and these profiles were analysed. The spatially continuous observations were made at a 125 m tall mast in a boreal pine forest. Airflows near forest canopies diverge from typical boundary layer flows due to the influence of roughness elements (i.e. trees) on the flow. Ideally, these complex flows should be studied with spatially continuous measurements, yet such measurements are not feasible with conventional micrometeorological measurements with, for example, sonic anemometers. Hence, the suitability of DTS measurements for studying canopy flows was assessed. The DTS measurements were able to discern continuous profiles of turbulent fluctuations and mean values of air temperature along the mast, providing information about mixing processes (e.g. canopy eddies and evolution of inversion layers at night) and up to third-order turbulence statistics across the forest–atmosphere interface. Turbulence measurements with 3D sonic anemometers and Doppler lidar at the site were also utilised in this analysis. The continuous profiles for turbulence statistics were in line with prior studies made at wind tunnels and large eddy simulations for canopy flows. The DTS measurements contained a significant noise component which was, however, quantified, and its effect on turbulence statistics was accounted for. Underestimation of air temperature fluctuations at high frequencies caused 20 %–30 % underestimation of temperature variance at typical flow conditions. Despite these limitations, the DTS measurements should prove useful also in other studies concentrating on flows near roughness elements and/or non-stationary periods, since the measurements revealed spatio-temporal patterns of the flow which were not possible to be discerned from single point measurements fixed in space.
Funder
Biotieteiden ja Ympäristön Tutkimuksen Toimikunta
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference94 articles.
1. Alekseychik, P., Mammarella, I., Launiainen, S., Rannik, U., and Vesala, T.:
Evolution of the nocturnal decoupled layer in a pine forest canopy,
Agr. Forest Meteorol., 174–175, 15–27,
https://doi.org/10.1016/j.agrformet.2013.01.011, 2013. a 2. Aubinet, M., Feigenwinter, C., Heinesch, B., Bernhofer, C., Canepa, E.,
Lindroth, A., Montagnani, L., Rebmann, C., Sedlak, P., and Van Gorsel, E.:
Direct advection measurements do not help to solve the night-time CO<span class="inline-formula"><sub>2</sub></span>
closure problem: Evidence from three different forests, Agr.
Forest Meteorol., 150, 655–664, https://doi.org/10.1016/j.agrformet.2010.01.016,
2010. a 3. Baldocchi, D.: Measuring fluxes of trace gases and energy between ecosystems
and the atmosphere – the state and future of the eddy covariance method,
Glob. Change Biol., 20, 3600–3609, https://doi.org/10.1111/gcb.12649, 2014. a 4. Barlow, J. F.: Progress in observing and modelling the urban boundary layer, Urban Climate, 10, 216–240,
https://doi.org/10.1016/j.uclim.2014.03.011, 2014. a 5. Bohrer, G., Katul, G. G., Walko, R. L., and Avissar, R.: Exploring the Effects of Microscale Structural Heterogeneity of Forest Canopies Using Large-Eddy Simulations, Bound.-Lay. Meteorol., 132, 351–382,
https://doi.org/10.1007/s10546-009-9404-4, 2009. a
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