Abstract: Floating vertical wind profile sensor or LiDAR device (1) comprising a vertical wind profile sensor sensor (8) for sensing a vertical wind profile, a self-propulsion system (24) for propelling the device through a body of water, and a deployable special mark (10), actuatable to switch between a deployed state for identifying the device as a special marker buoy and an undeployed state for identifying the device as a vessel. A controller (22) is provided for switching the device (1) from a vessel mode to a buoy mode when the vessel is anchored. The controller (22) switches the special mark (10) to the deployed state when the device (1) is in the buoy mode. The method involves the floating LiDAR device (1) navigating to a target location and the buoy mode being activated while vertical wind profile data are collected.