Decomposing velocity measurements

The quality-controlled velocities can be detrended before being further analysed to determine mean flow past the sensor and surface wave statistics. These quantities are necessary for later choosing the appropriate inertial subrange model for spectral fitting. Quality-controlled velocities may also need to be detrended before applying various despiking. Because estimating [math]\displaystyle{ \varepsilon }[/math] is done from the spectral observations, the analysis is insensitive to this step provided that we don’t filter out the scales shorter than the segment length.

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  512 s segment of the measured velocities after applying different detrending methods

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  Example velocity spectra of the short 512 s of records before and after different detrending techniques applied to the original 6h time series. The impact of the detrending method can be seen at the lowest frequencies only

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