The University of Southampton
University of Southampton Institutional Repository

Dune initiation in a bimodal wind regime

Dune initiation in a bimodal wind regime
Dune initiation in a bimodal wind regime

Early-stage bedforms develop into mature dunes through complex interactions between wind, sand transport, and surface topography. Depending on varying environmental and wind conditions, the mechanisms driving dune formation and, ultimately, the shape of nascent dunes may differ markedly. In cases where sand availability is plentiful, the emergence and growth of dunes can be studied with a linear stability analysis of coupled transport and hydrodynamic equations. Until now, this analysis has only been applied using field evidence in unidirectional winds. However, in many areas of the world and on other planets, wind regimes are more often bimodal or multimodal. Here, we investigate field evidence of protodune formation under a bimodal wind regime by applying linear stability analysis to a developing protodune field. Employing recent development of the linear stability theory and experimental research, combined with in situ wind, sediment transport, and topographic measurements during a monthlong field campaign at Great Sand Dunes National Park, Colorado, USA, we predict the spatial characteristics (orientation and wavelength) and temporal evolution (growth rate and migration velocity) of a protodune field. We find that the theoretical predictions compare well with measured dunefield attributes as characterized by high-resolution Digital Elevation Models measured using repeat terrestrial laser scanning. Our findings suggest that linear stability analysis is a quantitative predictor of protodune development on sandy surfaces with a bimodal wind regime. This result is significant as it offers critical validation of the linear stability analysis for explaining the initiation and development of dunes toward maturity in a complex natural environment.

2169-9011
Delorme, Pauline
d7e1a2d1-82e0-4c82-ae92-75d8ada3e51e
Wiggs, Giles F.S.
f038d628-5691-4c54-a7a2-148049f5feac
Baddock, Matthew C.
0ce5834e-7f4a-47f3-99b2-2376e2499c02
Claudin, Philippe
bc540459-6b06-4c62-a8ea-2b05b760b3ad
Nield, Joanna
173be2c5-b953-481a-abc4-c095e5e4b790
Valdez, Andrew
044560f8-e971-429f-8e45-50ebf6849f2f
Delorme, Pauline
d7e1a2d1-82e0-4c82-ae92-75d8ada3e51e
Wiggs, Giles F.S.
f038d628-5691-4c54-a7a2-148049f5feac
Baddock, Matthew C.
0ce5834e-7f4a-47f3-99b2-2376e2499c02
Claudin, Philippe
bc540459-6b06-4c62-a8ea-2b05b760b3ad
Nield, Joanna
173be2c5-b953-481a-abc4-c095e5e4b790
Valdez, Andrew
044560f8-e971-429f-8e45-50ebf6849f2f

Delorme, Pauline, Wiggs, Giles F.S., Baddock, Matthew C., Claudin, Philippe, Nield, Joanna and Valdez, Andrew (2020) Dune initiation in a bimodal wind regime. Journal of Geophysical Research: Earth Surface, 125 (11), [e2020JF005757]. (doi:10.1029/2020JF005757).

Record type: Article

Abstract

Early-stage bedforms develop into mature dunes through complex interactions between wind, sand transport, and surface topography. Depending on varying environmental and wind conditions, the mechanisms driving dune formation and, ultimately, the shape of nascent dunes may differ markedly. In cases where sand availability is plentiful, the emergence and growth of dunes can be studied with a linear stability analysis of coupled transport and hydrodynamic equations. Until now, this analysis has only been applied using field evidence in unidirectional winds. However, in many areas of the world and on other planets, wind regimes are more often bimodal or multimodal. Here, we investigate field evidence of protodune formation under a bimodal wind regime by applying linear stability analysis to a developing protodune field. Employing recent development of the linear stability theory and experimental research, combined with in situ wind, sediment transport, and topographic measurements during a monthlong field campaign at Great Sand Dunes National Park, Colorado, USA, we predict the spatial characteristics (orientation and wavelength) and temporal evolution (growth rate and migration velocity) of a protodune field. We find that the theoretical predictions compare well with measured dunefield attributes as characterized by high-resolution Digital Elevation Models measured using repeat terrestrial laser scanning. Our findings suggest that linear stability analysis is a quantitative predictor of protodune development on sandy surfaces with a bimodal wind regime. This result is significant as it offers critical validation of the linear stability analysis for explaining the initiation and development of dunes toward maturity in a complex natural environment.

Text
dune_initiation_bimodal - Accepted Manuscript
Download (4kB)

More information

Accepted/In Press date: 18 September 2020
e-pub ahead of print date: 14 November 2020
Published date: November 2020

Identifiers

Local EPrints ID: 444171
URI: http://eprints.soton.ac.uk/id/eprint/444171
ISSN: 2169-9011
PURE UUID: 504c538f-005f-4ddd-ab9f-5a9ca3168041
ORCID for Joanna Nield: ORCID iD orcid.org/0000-0002-2657-0525

Catalogue record

Date deposited: 30 Sep 2020 16:30
Last modified: 20 Feb 2021 02:41

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×