Longitudinal or seif dunes are dunes that are parallel to a strong wind that blows in one general direction.
纵向或者赛夫沙丘是与强风平行的沙丘，风总是以相同方向刮过。
2
Shifting of dune had horizontal direction (ne SW) and longitudinal direction (NW SE) and irregular formation formed with varied wind direction.
沙丘走向有横向(NE - SW)和纵向(NW - SE)以及多风向形成的不规则形。
3
Feasibility is discussed that a multi-longitudinal mode laser is employed as the detection light source of the double-edge technique for Doppler lidar wind measurement.