The reference lidar MUSA (in fixed or mobile configuration) is a multi-wavelength depolarization Raman with 3 elastic – 1064, 532, 355 nm, 2 Raman – 607, 387 nm, and linear depolarization ratio at 532 nm. It is the only reference instrument operating simultaneously 3 elastic (including the infrared) and 2 Raman channels. The system can be moved at the user site (if the user’s lidar is fixed) or can be operated at the host for longer intercomparisons.