Faculty Publications

Influence Of Topography On Wind Speed Over A Coastal Dune And Blowout System At Jockey's Ridge, NC, USA

Document Type

Article

Keywords

Blowout, Dune, Fractional wind speed-up, Topographic variability

Journal/Book/Conference Title

Earth Surface Processes and Landforms

Volume

40

Issue

7

First Page

853

Last Page

863

Abstract

This study examines the spatial distribution of wind speed across a coastal dune system located at Jockey's Ridge State Park, North Carolina. The study area consists of a trough blowout through a foredune ridge, and the landforms that have developed behind the foredune. Wind speed and direction were measured simultaneously with single sensors placed at a fixed height in 13 locations across the blowout/dune complex. Fractional wind speed-up is computed for sampling stations using data from a mast located on the beach as the reference. Results show that wind speeds were generally accelerated across the study site. The highest speeds were recorded on the foredune ridges adjacent to the blowout. Wind was accelerated through the center of the blowout throat and along the downwind lateral wall. Further into the blowout, at the base of the ramp to the depositional lobe, higher wind speeds shifted to the upwind lateral wall and continued to accelerate up the ramp as air exited to the rear. Significant variations in the wind speed-up pattern were associated with different wind approach angles, with greater speed-up occurring when the winds were aligned normal to the dune system. The speed-up decreased as the angle of approach became increasingly oblique to the ridge. The patterns of wind speed-up across the site point to the influence of topography on airflow. To quantify the relationship, measures of several topographic variables were obtained along sample transects running upwind from each sample station along flow lines representing different wind approach angles. Examination of correlation coefficients between wind speed-up and topographic variables suggests that for groups of stations with similar topographic characteristics, 30-50% of the variations in speed-up may be explained by the upwind topographic variability.

Department

Department of Geography

Original Publication Date

6-15-2015

DOI of published version

10.1002/esp.3670

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