Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer
Conventional and recently developed approaches for estimating turbulent scalar fluxes under stable atmospheric conditions are evaluated, with a focus on gases for which fast sensors are not readily available. First, the relaxed eddy accumulation (REA) classical approach and a recently proposed mixin...
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ftdoajarticles:oai:doaj.org/article:7bf42cc97c3544848fd763f994735b52 2024-09-15T18:39:52+00:00 Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer M. Allouche V. I. Sevostianov E. Zahn M. A. Zondlo N. L. Dias G. G. Katul J. D. Fuentes E. Bou-Zeid 2024-08-01T00:00:00Z https://doi.org/10.5194/acp-24-9697-2024 https://doaj.org/article/7bf42cc97c3544848fd763f994735b52 EN eng Copernicus Publications https://acp.copernicus.org/articles/24/9697/2024/acp-24-9697-2024.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-24-9697-2024 1680-7316 1680-7324 https://doaj.org/article/7bf42cc97c3544848fd763f994735b52 Atmospheric Chemistry and Physics, Vol 24, Pp 9697-9711 (2024) Physics QC1-999 Chemistry QD1-999 article 2024 ftdoajarticles https://doi.org/10.5194/acp-24-9697-2024 2024-09-02T15:34:37Z Conventional and recently developed approaches for estimating turbulent scalar fluxes under stable atmospheric conditions are evaluated, with a focus on gases for which fast sensors are not readily available. First, the relaxed eddy accumulation (REA) classical approach and a recently proposed mixing length parameterization, labeled A22, are tested against eddy-covariance computations. Using high-frequency measurements collected from two contrasting sites (the frozen tundra near Utqiaġvik, Alaska, and a sparsely vegetated grassland in Wendell, Idaho, during winter), it is shown that the REA and A22 models outperform the conventional Monin–Obukhov similarity theory (MOST) utilized widely to infer fluxes from mean gradients. Second, scenarios where slow trace gas sensors are the only viable option in field measurements are investigated using digital filtering applied to fast-response sensors to simulate their slow-response counterparts. With a filtered scalar signal, the observed filtered eddy-covariance fluxes are referred to here as large-eddy-covariance (LEC) fluxes. A virtual eddy accumulation (VEA) approach, akin to the REA model but not requiring a mechanical apparatus to separate the gas flows, is also formulated and tested. A22 outperforms VEA and LEC in predicting the observed unfiltered (total) eddy-covariance (EC) fluxes; however, VEA can still capture the LEC fluxes well. This finding motivates the introduction of a sensor response time correction into the VEA formulation to offset the effect of sensor filtering on the underestimated net averaged fluxes. The only needed parameter for this correction is the mean velocity at the instrument height, a surrogate of the advective timescale. The VEA approach is very suitable and simple to use with gas sensors of intermediate speed ( ∼ 0.5 to 1 Hz ) and with conventional open- or closed-path setups. Article in Journal/Newspaper Tundra Alaska Directory of Open Access Journals: DOAJ Articles Atmospheric Chemistry and Physics 24 16 9697 9711 |
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Directory of Open Access Journals: DOAJ Articles |
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English |
topic |
Physics QC1-999 Chemistry QD1-999 |
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Physics QC1-999 Chemistry QD1-999 M. Allouche V. I. Sevostianov E. Zahn M. A. Zondlo N. L. Dias G. G. Katul J. D. Fuentes E. Bou-Zeid Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
topic_facet |
Physics QC1-999 Chemistry QD1-999 |
description |
Conventional and recently developed approaches for estimating turbulent scalar fluxes under stable atmospheric conditions are evaluated, with a focus on gases for which fast sensors are not readily available. First, the relaxed eddy accumulation (REA) classical approach and a recently proposed mixing length parameterization, labeled A22, are tested against eddy-covariance computations. Using high-frequency measurements collected from two contrasting sites (the frozen tundra near Utqiaġvik, Alaska, and a sparsely vegetated grassland in Wendell, Idaho, during winter), it is shown that the REA and A22 models outperform the conventional Monin–Obukhov similarity theory (MOST) utilized widely to infer fluxes from mean gradients. Second, scenarios where slow trace gas sensors are the only viable option in field measurements are investigated using digital filtering applied to fast-response sensors to simulate their slow-response counterparts. With a filtered scalar signal, the observed filtered eddy-covariance fluxes are referred to here as large-eddy-covariance (LEC) fluxes. A virtual eddy accumulation (VEA) approach, akin to the REA model but not requiring a mechanical apparatus to separate the gas flows, is also formulated and tested. A22 outperforms VEA and LEC in predicting the observed unfiltered (total) eddy-covariance (EC) fluxes; however, VEA can still capture the LEC fluxes well. This finding motivates the introduction of a sensor response time correction into the VEA formulation to offset the effect of sensor filtering on the underestimated net averaged fluxes. The only needed parameter for this correction is the mean velocity at the instrument height, a surrogate of the advective timescale. The VEA approach is very suitable and simple to use with gas sensors of intermediate speed ( ∼ 0.5 to 1 Hz ) and with conventional open- or closed-path setups. |
format |
Article in Journal/Newspaper |
author |
M. Allouche V. I. Sevostianov E. Zahn M. A. Zondlo N. L. Dias G. G. Katul J. D. Fuentes E. Bou-Zeid |
author_facet |
M. Allouche V. I. Sevostianov E. Zahn M. A. Zondlo N. L. Dias G. G. Katul J. D. Fuentes E. Bou-Zeid |
author_sort |
M. Allouche |
title |
Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
title_short |
Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
title_full |
Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
title_fullStr |
Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
title_full_unstemmed |
Estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
title_sort |
estimating scalar turbulent fluxes with slow-response sensors in the stable atmospheric boundary layer |
publisher |
Copernicus Publications |
publishDate |
2024 |
url |
https://doi.org/10.5194/acp-24-9697-2024 https://doaj.org/article/7bf42cc97c3544848fd763f994735b52 |
genre |
Tundra Alaska |
genre_facet |
Tundra Alaska |
op_source |
Atmospheric Chemistry and Physics, Vol 24, Pp 9697-9711 (2024) |
op_relation |
https://acp.copernicus.org/articles/24/9697/2024/acp-24-9697-2024.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-24-9697-2024 1680-7316 1680-7324 https://doaj.org/article/7bf42cc97c3544848fd763f994735b52 |
op_doi |
https://doi.org/10.5194/acp-24-9697-2024 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
24 |
container_issue |
16 |
container_start_page |
9697 |
op_container_end_page |
9711 |
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1810484202785734656 |