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River Plume Liftoff Dynamics and Surface Expressions

The water surface expression of liftoff and its dependence on discharge are examined using numerical simulations with the Regional Ocean Modeling System (ROMS). Liftoff is the process by which buoyant river water separates from the bed and flows over denser saltwater. During low‐discharge conditions...

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Autores principales: Branch, R. A., Horner‐Devine, A. R., Kumar, N., Poggioli, A. R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7507782/
https://www.ncbi.nlm.nih.gov/pubmed/32999509
http://dx.doi.org/10.1029/2019WR026475
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author Branch, R. A.
Horner‐Devine, A. R.
Kumar, N.
Poggioli, A. R.
author_facet Branch, R. A.
Horner‐Devine, A. R.
Kumar, N.
Poggioli, A. R.
author_sort Branch, R. A.
collection PubMed
description The water surface expression of liftoff and its dependence on discharge are examined using numerical simulations with the Regional Ocean Modeling System (ROMS). Liftoff is the process by which buoyant river water separates from the bed and flows over denser saltwater. During low‐discharge conditions liftoff occurs in the river and is accompanied by a change in the surface slope. During high‐discharge conditions liftoff occurs outside the mouth and generates a ridge on the water surface. The location and height of the ridge can be described by analytical equations in terms of discharge, shelf slope, and river mouth aspect ratio. The offshore distance and height of the ridge are proportional to the river discharge and vary inversely with river mouth aspect ratio. For steep shelf slopes liftoff occurs close to the river mouth and generates a large ridge. The ridge is modified, but not eliminated, by the presence of tides. The water surface slope change at the ridge peak is large enough to be detected by the upcoming Surface Water and Ocean Topography (SWOT) altimeter and can be used to identify the liftoff location during high discharge. However, during low discharge the water surface slope change at the liftoff location is too small to be detected by SWOT. These results indicate that remote measurements of the presence or absence of the ridge may be useful to distinguish between low and high flows, and remote measurements of the ridge location or height could be used to estimate freshwater discharge.
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spelling pubmed-75077822020-09-28 River Plume Liftoff Dynamics and Surface Expressions Branch, R. A. Horner‐Devine, A. R. Kumar, N. Poggioli, A. R. Water Resour Res Research Articles The water surface expression of liftoff and its dependence on discharge are examined using numerical simulations with the Regional Ocean Modeling System (ROMS). Liftoff is the process by which buoyant river water separates from the bed and flows over denser saltwater. During low‐discharge conditions liftoff occurs in the river and is accompanied by a change in the surface slope. During high‐discharge conditions liftoff occurs outside the mouth and generates a ridge on the water surface. The location and height of the ridge can be described by analytical equations in terms of discharge, shelf slope, and river mouth aspect ratio. The offshore distance and height of the ridge are proportional to the river discharge and vary inversely with river mouth aspect ratio. For steep shelf slopes liftoff occurs close to the river mouth and generates a large ridge. The ridge is modified, but not eliminated, by the presence of tides. The water surface slope change at the ridge peak is large enough to be detected by the upcoming Surface Water and Ocean Topography (SWOT) altimeter and can be used to identify the liftoff location during high discharge. However, during low discharge the water surface slope change at the liftoff location is too small to be detected by SWOT. These results indicate that remote measurements of the presence or absence of the ridge may be useful to distinguish between low and high flows, and remote measurements of the ridge location or height could be used to estimate freshwater discharge. John Wiley and Sons Inc. 2020-07-16 2020-07 /pmc/articles/PMC7507782/ /pubmed/32999509 http://dx.doi.org/10.1029/2019WR026475 Text en ©2020. The Authors. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Articles
Branch, R. A.
Horner‐Devine, A. R.
Kumar, N.
Poggioli, A. R.
River Plume Liftoff Dynamics and Surface Expressions
title River Plume Liftoff Dynamics and Surface Expressions
title_full River Plume Liftoff Dynamics and Surface Expressions
title_fullStr River Plume Liftoff Dynamics and Surface Expressions
title_full_unstemmed River Plume Liftoff Dynamics and Surface Expressions
title_short River Plume Liftoff Dynamics and Surface Expressions
title_sort river plume liftoff dynamics and surface expressions
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7507782/
https://www.ncbi.nlm.nih.gov/pubmed/32999509
http://dx.doi.org/10.1029/2019WR026475
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