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  • ADCP Velocity Computation: Correction and Rotation to East-North-Up Co-ordinate System, Three-beam Solutions and Screening

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In cases where the data quality team has determined that an entire beam is bad, they can supply a device attribute specifying the bad beam number. That beam is then excluded in the processing from beam or instr co-ords and the values are filled in with the three-beam solution. Only the U,V,W results are affected, the raw velocity data as recorded by the instrument is presented without the exclusion. This forces the 3 beam option to on, regardless of the user input. The excluded beam number is mentioned in a comment on both the currents plot and intensity plots and in the processing comments in the mat files. This is currently only available for RDI ADCPs with 4 beams.

Once in Earth co-ordinates, the data can also be screened by the error velocity. Error velocity screening only applies to data with four valid beams (and non-zero error velocities). For further infromation on the screening steps, including algorithms, see adcp coordinate transformation_Jan08.pdf

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