@Miraz I did a Google search on "perpendicular dune system" and got data that matches what @yorrike already said. The perpendicular refers to perpendicular to the direction of the wind. Barchan dunes can become aligned together along a plane perpendicular to the wind. If the line becomes somewhat straight, dune scientists refer to these forward marching ridges as transverse dunes.
Transverse dunes are perpendicular to the wind direction and occur where there is an abundant source of sand.
Poke around in the results of the Google search and you'll see these details, some with pictures.
RC