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Variable Physical Drivers of Near-Surface Turbulence in a Regulated River

Guseva, S. and Aurela, M. and Cortes, A. and Kivi, R. and Lotsari, E. and MacIntyre, S. and Mammarella, I and Ojala, A. and Stepanenko, V and Uotila, P. and Vaha, A. and Vesala, T. and Wallin, Marcus and Lorke, A. (2021). Variable Physical Drivers of Near-Surface Turbulence in a Regulated River. Water Resources Research. 57 , e2020WR027939
[Research article]

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Abstract

Inland waters, such as lakes, reservoirs and rivers, are important sources of climate forcing trace gases. A key parameter that regulates the gas exchange between water and the atmosphere is the gas transfer velocity, which itself is controlled by near-surface turbulence in the water. While in lakes and reservoirs, near-surface turbulence is mainly driven by atmospheric forcing, in shallow rivers and streams it is generated by bottom friction of gravity-forced flow. Large rivers represent a transition between these two cases. Near-surface turbulence has rarely been measured in rivers and the drivers of turbulence have not been quantified. We analyzed continuous measurements of flow velocity and quantified turbulence as the rate of dissipation of turbulent kinetic energy over the ice-free season in a large regulated river in Northern Finland. Measured dissipation rates agreed with predictions from bulk parameters, including mean flow velocity, wind speed, surface heat flux, and with a one-dimensional numerical turbulence model. Values ranged from similar to 10-10m2s-3 to 10-5m2s-3. Atmospheric forcing or gravity was the dominant driver of near-surface turbulence for similar fraction of the time. Large variability in near-surface dissipation rate occurred at diel time scales, when the flow velocity was strongly affected by downstream dam operation. By combining scaling relations for boundary-layer turbulence at the river bed and at the air-water interface, we derived a simple model for estimating the relative contributions of wind speed and bottom friction of river flow as a function of depth.

Authors/Creators:Guseva, S. and Aurela, M. and Cortes, A. and Kivi, R. and Lotsari, E. and MacIntyre, S. and Mammarella, I and Ojala, A. and Stepanenko, V and Uotila, P. and Vaha, A. and Vesala, T. and Wallin, Marcus and Lorke, A.
Title:Variable Physical Drivers of Near-Surface Turbulence in a Regulated River
Series Name/Journal:Water Resources Research
Year of publishing :2021
Volume:57
Article number:e2020WR027939
Number of Pages:27
Publisher:AMER GEOPHYSICAL UNION
ISSN:0043-1397
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Oceanography, Hydrology, Water Resources
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Climate Research
Keywords:river, turbulence, gas exchange, wind
URN:NBN:urn:nbn:se:slu:epsilon-p-115035
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-115035
Additional ID:
Type of IDID
DOI10.1029/2020WR027939
Web of Science (WoS)000723106900008
ID Code:26680
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
Deposited By: SLUpub Connector
Deposited On:11 Jan 2022 10:25
Metadata Last Modified:11 Jan 2022 10:31

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