The Multi-Scale Layering-Structure of Thermal Microscale Profiles

Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses....

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Autor principal:	Andrew Folkard
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	fractal lakes mixing multi-scale stratification turbulence Hydraulic engineering TC1-978 Water supply for domestic and industrial purposes TD201-500
Acceso en línea:	https://doaj.org/article/95a62e289efa4912943db542ced23491
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spelling	oai:doaj.org-article:95a62e289efa4912943db542ced234912021-11-11T19:55:35ZThe Multi-Scale Layering-Structure of Thermal Microscale Profiles10.3390/w132130422073-4441https://doaj.org/article/95a62e289efa4912943db542ced234912021-11-01T00:00:00Zhttps://www.mdpi.com/2073-4441/13/21/3042https://doaj.org/toc/2073-4441Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses. Hence, turbulent mixing and stratification processes remain greatly under-sampled. This paper contributes to addressing this problem by presenting a novel analysis of thermal microstructure profiles, focusing on their multi-scale stratification structure. Profiles taken in two small lakes using a Self-Contained Automated Micro-Profiler (SCAMP) were analysed. For each profile, buoyancy frequency (N), Thorpe scales (L<sub>T</sub>), and the coefficient of vertical turbulent diffusivity (K<sub>Z</sub>) were determined. To characterize the multi-scale stratification, profiles of d<sup>2</sup>T/dz<sup>2</sup> at a spectrum of scales were calculated and the number of turning points in them counted. Plotting these counts against the scale gave pseudo-spectra, which were characterized by the index D of their power law regression lines. Scale-dependent correlations of D with N, L<sub>T</sub> and K<sub>Z</sub> were found, and suggest that this approach may be useful for providing alternative estimates of the efficiency of turbulent mixing and measures of longer-term averages of K<sub>Z</sub> than current methods provide. Testing these potential uses will require comparison of field measurements of D with time-integrated K<sub>Z</sub> values and numerical simulations.Andrew FolkardMDPI AGarticlefractallakesmixingmulti-scalestratificationturbulenceHydraulic engineeringTC1-978Water supply for domestic and industrial purposesTD201-500ENWater, Vol 13, Iss 3042, p 3042 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	fractal lakes mixing multi-scale stratification turbulence Hydraulic engineering TC1-978 Water supply for domestic and industrial purposes TD201-500
spellingShingle	fractal lakes mixing multi-scale stratification turbulence Hydraulic engineering TC1-978 Water supply for domestic and industrial purposes TD201-500 Andrew Folkard The Multi-Scale Layering-Structure of Thermal Microscale Profiles
description	Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses. Hence, turbulent mixing and stratification processes remain greatly under-sampled. This paper contributes to addressing this problem by presenting a novel analysis of thermal microstructure profiles, focusing on their multi-scale stratification structure. Profiles taken in two small lakes using a Self-Contained Automated Micro-Profiler (SCAMP) were analysed. For each profile, buoyancy frequency (N), Thorpe scales (L<sub>T</sub>), and the coefficient of vertical turbulent diffusivity (K<sub>Z</sub>) were determined. To characterize the multi-scale stratification, profiles of d<sup>2</sup>T/dz<sup>2</sup> at a spectrum of scales were calculated and the number of turning points in them counted. Plotting these counts against the scale gave pseudo-spectra, which were characterized by the index D of their power law regression lines. Scale-dependent correlations of D with N, L<sub>T</sub> and K<sub>Z</sub> were found, and suggest that this approach may be useful for providing alternative estimates of the efficiency of turbulent mixing and measures of longer-term averages of K<sub>Z</sub> than current methods provide. Testing these potential uses will require comparison of field measurements of D with time-integrated K<sub>Z</sub> values and numerical simulations.
format	article
author	Andrew Folkard
author_facet	Andrew Folkard
author_sort	Andrew Folkard
title	The Multi-Scale Layering-Structure of Thermal Microscale Profiles
title_short	The Multi-Scale Layering-Structure of Thermal Microscale Profiles
title_full	The Multi-Scale Layering-Structure of Thermal Microscale Profiles
title_fullStr	The Multi-Scale Layering-Structure of Thermal Microscale Profiles
title_full_unstemmed	The Multi-Scale Layering-Structure of Thermal Microscale Profiles
title_sort	multi-scale layering-structure of thermal microscale profiles
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/95a62e289efa4912943db542ced23491
work_keys_str_mv	AT andrewfolkard themultiscalelayeringstructureofthermalmicroscaleprofiles AT andrewfolkard multiscalelayeringstructureofthermalmicroscaleprofiles
_version_	1718431364322164736

The Multi-Scale Layering-Structure of Thermal Microscale Profiles

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