Effects of wave exposure on circulation in a temperate reef environment

Graham Symonds, Liejun Zhong, Nick A. Mortimer

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

Observations of waves and currents in a temperate reef environment off southwestern Western Australia over a period of 1 year reveal the relative importance of wind and wave forcing. During periods of low waves, linear regression analysis shows alongshore currents seaward and shoreward of the reef line are reasonably well predicted using 1% and 0.5% of the wind speed, respectively. However, shoreward of the reef line anomalously strong currents were often observed during periods of light or even opposing winds and the mean sea surface was elevated relative to offshore of the reefs. These anomalous currents and elevated sea level occur during periods of high waves and both are correlated with the root-mean-square wave height seaward of the reefs, similar to what has been observed in coral reef environments. The observations were simulated with the numerical model XBeach which includes radiation stress forcing due to the presence of the waves. The model was also used to examine the dynamics of the wave-driven flow in terms of the momentum balance. As on a coral reef, through the surf zone over the reef bottom, friction is balanced by the sum of the radiation stress gradient and pressure gradient. Away from the reefs the radiation stress gradients are small and the momentum balance is between bottom friction and pressure gradient.

Original languageEnglish
Article numberC09010
Number of pages11
JournalJournal of Geophysical Research: Oceans
Volume116
Issue number9
DOIs
Publication statusPublished - 13 Sep 2011
Externally publishedYes

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