Remote sensing for estimating impact of internal waves on the seabed
In-situ observation and modelling of internal waves in the UK continental shelf (UKCS) has a long history. Internal waves can reach amplitudes of 50m and more, transferring energy between large-scale tides and small-scale mixing, and contribute to coupling of benthic and pelagic systems, sediment resuspension and pollutant dispersion. Detailed in-situ observations and modelling of internal wave (IW) hot spots help us to understand the principles of their interaction with the seabed of the continental shelf and slope. Such measurements are focused on specific areas and not able to provide an overall picture of IW occurrence on the UKCS, or their seasonal or inter-annual variability. Satellite remote sensing using a synthetic aperture radar (SAR) sensor can deliver thousands of measurements of sea surface roughness and provide systematic observations of IW features over many years. SAR remote sensing opens new opportunities for deriving IW occurrence and climatology maps over the UKCS.
In this study we processed ENVISAT ASAR sensor data acquired in 2006-2012 by the European Space Agency, to build detailed maps of IW occurrence and climatology for the UKCS. Up to a hundred SAR scenes per month covered the region of interest, over 3,400 in total, a volume of data that cannot be processed manually.
In this project we developed a new methodology for automated processing of satellite images, detection of IW features and combining the processed scenes into monthly composites and climatologies of IW occurrence. These IW occurrence maps have been applied to estimate the impact of IWs on the seabed in the UKCS. Regions with high likelihood of seabed disturbance were identified by combining the mixed layer depth, bathymetry and IW occurrence data. Monthly and annual climatology maps of the UKCS have been produced showing the spatial and temporal variability of high and low impact regions. The project ran from January to September 2017 funded by the UK Department for Business Energy and Industrial Strategy's (BEIS) offshore energy Strategic Environmental Assessment (SEA) programme.
|Keywords:||Internal waves, Remote Sensing, Maps, Continental shelf|
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