Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics

Abstract In inland water covering lakes, reservoirs, and ponds, the gas exchange of slightly soluble gases such as carbon dioxide, dimethyl sulfide, methane, or oxygen across a clean and nearly flat air‐water interface is routinely described using a water‐side mean gas transfer velocity kL‾, where o...

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Main Authors: Gabriel Katul, Andrew Bragg, Ivan Mammarella, Heping Liu, Qi Li, Elie Bou‐Zeid
Format: Article
Language:English
Published: Wiley 2024-11-01
Series:Water Resources Research
Subjects:
Online Access:https://doi.org/10.1029/2023WR036615
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author Gabriel Katul
Andrew Bragg
Ivan Mammarella
Heping Liu
Qi Li
Elie Bou‐Zeid
author_facet Gabriel Katul
Andrew Bragg
Ivan Mammarella
Heping Liu
Qi Li
Elie Bou‐Zeid
author_sort Gabriel Katul
collection DOAJ
description Abstract In inland water covering lakes, reservoirs, and ponds, the gas exchange of slightly soluble gases such as carbon dioxide, dimethyl sulfide, methane, or oxygen across a clean and nearly flat air‐water interface is routinely described using a water‐side mean gas transfer velocity kL‾, where overline indicates time or ensemble averaging. The micro‐eddy surface renewal model predicts kL‾=αoSc−1/2νϵ‾1/4, where Sc is the molecular Schmidt number, ν is the water kinematic viscosity, and ϵ‾ is the waterside mean turbulent kinetic energy dissipation rate at or near the interface. While αo=0.39−0.46 has been reported across a number of data sets, others report large scatter or variability around this value range. It is shown here that this scatter can be partly explained by high temporal variability in instantaneous ϵ around ϵ‾, a mechanism that was not previously considered. As the coefficient of variation CVe in ϵ increases, αo must be adjusted by a multiplier 1+CVe2−3/32 that was derived from a log‐normal model for the probability density function of ϵ. Reported variations in αo with a macro‐scale Reynolds number can also be partly attributed to intermittency effects in ϵ. Such intermittency is characterized by the long‐range (i.e., power‐law decay) spatial auto‐correlation function of ϵ. That αo varies with a macro‐scale Reynolds number does not necessarily violate the micro‐eddy model. Instead, it points to a coordination between the macro‐ and micro‐scales arising from the transfer of energy across scales in the energy cascade.
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spelling doaj-art-14cdc302e7ea46528fd496668ecb64542025-08-23T13:05:51ZengWileyWater Resources Research0043-13971944-79732024-11-016011n/an/a10.1029/2023WR036615Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐StatisticsGabriel Katul0Andrew Bragg1Ivan Mammarella2Heping Liu3Qi Li4Elie Bou‐Zeid5Department of Civil and Environmental Engineering Duke University Durham NC USADepartment of Civil and Environmental Engineering Duke University Durham NC USAFaculty of Science Institute for Atmospheric and Earth System Research/Physics University of Helsinki Helsinki FinlandDepartment of Civil and Environmental Engineering Washington State University Pullman WA USADepartment of Civil and Environmental Engineering Cornell University Ithaca NY USADepartment of Civil and Environmental Engineering Princeton University Princeton NJ USAAbstract In inland water covering lakes, reservoirs, and ponds, the gas exchange of slightly soluble gases such as carbon dioxide, dimethyl sulfide, methane, or oxygen across a clean and nearly flat air‐water interface is routinely described using a water‐side mean gas transfer velocity kL‾, where overline indicates time or ensemble averaging. The micro‐eddy surface renewal model predicts kL‾=αoSc−1/2νϵ‾1/4, where Sc is the molecular Schmidt number, ν is the water kinematic viscosity, and ϵ‾ is the waterside mean turbulent kinetic energy dissipation rate at or near the interface. While αo=0.39−0.46 has been reported across a number of data sets, others report large scatter or variability around this value range. It is shown here that this scatter can be partly explained by high temporal variability in instantaneous ϵ around ϵ‾, a mechanism that was not previously considered. As the coefficient of variation CVe in ϵ increases, αo must be adjusted by a multiplier 1+CVe2−3/32 that was derived from a log‐normal model for the probability density function of ϵ. Reported variations in αo with a macro‐scale Reynolds number can also be partly attributed to intermittency effects in ϵ. Such intermittency is characterized by the long‐range (i.e., power‐law decay) spatial auto‐correlation function of ϵ. That αo varies with a macro‐scale Reynolds number does not necessarily violate the micro‐eddy model. Instead, it points to a coordination between the macro‐ and micro‐scales arising from the transfer of energy across scales in the energy cascade.https://doi.org/10.1029/2023WR036615Batchelor scalemicro‐eddy modelgas transfer velocitysuperstatisticsair‐water exchangeintermittency
spellingShingle Gabriel Katul
Andrew Bragg
Ivan Mammarella
Heping Liu
Qi Li
Elie Bou‐Zeid
Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics
Water Resources Research
Batchelor scale
micro‐eddy model
gas transfer velocity
superstatistics
air‐water exchange
intermittency
title Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics
title_full Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics
title_fullStr Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics
title_full_unstemmed Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics
title_short Gas Transfer Across Air‐Water Interfaces in Inland Waters: From Micro‐Eddies to Super‐Statistics
title_sort gas transfer across air water interfaces in inland waters from micro eddies to super statistics
topic Batchelor scale
micro‐eddy model
gas transfer velocity
superstatistics
air‐water exchange
intermittency
url https://doi.org/10.1029/2023WR036615
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