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frank-engel-usgs / VMT

The Velocity Mapping Toolbox
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Issue with MCS Normal Vector #5

Closed Ryan-Jackson-USGS closed 7 years ago

Ryan-Jackson-USGS commented 7 years ago

There are two issues with the MCS normal vector reported in the VMT shiptrack plot in VMT 4.08 (r20170404).

  1. The mean flow direction vector and the MCS normal vector appear to be reversed. According to the user manual, the red vector is the normal vector and the black vector is the mean flow direction. image

However, the VMT_PlotShiptracks.m source code shows the red vector is the mean flow direction and the black vector is the normal vector. image

  1. In some cases, the normal vector to the MCS (black vector) is not plotted correctly or is incorrectly computed for the MCS. For example, here is a shiptrack plot from the Wabash cutoff dataset (01/07/09, transects 24-28; quad3) where the black normal vector is clearly incorrectly plotted. The log window shows the normal (streamwise) direction to be 231.7 deg which appears correct and is close to the primary flow direction, so I believe the issue is with the VMT_PlotShiptracks.m plotting function which recomputes the normal vector rather than using V.phi. image
frank-engel-usgs commented 7 years ago

@Ryan-Jackson-USGS I have resolved this issue. Thanks for pointing it out!