Spatial variability of wave fields over the scale of a wave energy test site
Ashton, Ian
Date: 29 July 2011
Thesis or dissertation
Publisher
University of Exeter
Degree Title
PhD in Earth Resources
Abstract
Accurate wave measurements are required for wave energy applications,
including resource assessments and performance assessments. In response,
wave data are measured from deployment sites, commonly using wave buoys
or other point wave sensors. Spatial variability in the wave field will introduce
inaccuracies to the analysis of data ...
Accurate wave measurements are required for wave energy applications,
including resource assessments and performance assessments. In response,
wave data are measured from deployment sites, commonly using wave buoys
or other point wave sensors. Spatial variability in the wave field will introduce
inaccuracies to the analysis of data captured from a single point to
represent a separate location or area. This thesis describes research undertaken
to quantify the effect of spatial variability on the accuracy of direct
wave measurements taken at a wave energy site. An array of four timesynchronised
wave buoys were deployed, separated by 500m, in a location
close to the Wave Hub wave energy test site in Cornwall, UK. These data
were subject to close scrutiny in terms of data processing and quality control,
which raised specific issues regarding data processing and the validation
of wave data for a new measurement facility. Specific recommendations are
made for data captured from this facility, and bespoke quality control routines
were developed. This process minimises the possible contribution of
errors to the processed data, which is observed to be of the highest importance
when analysing simultaneous data sets, and provides a data set that is
particularly suited to the examination of the spatial characteristics of ocean
waves. The differences between simultaneous data demonstrated local physical
processes to be causing a deterministic difference between the waves at
the measurement sites, which contributed to a significant difference between
the power statistics at different locations within the site. Instantaneous differences
between measurements were observed to agree well with theoretical
estimations of random error, based on sampling theory. The culmination of
the research is a unique analysis of the spatial properties of ocean wave fields
on the scale of a wave energy test site, of direct relevance to the development
and monitoring of wave energy test sites.
Doctoral Theses
Doctoral College
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