Add a new AERONET stream - maritime measurements (MAN)

Hello again @dbowdalo

Just I've opened this issue to start planning to add a new AERONET stream in the GHOST dataset. It's the one related to the MARITIME AEROSOL NETWORK (MAN).

We will need to revise the information about the instrument and the retrieval, but also, in this case, it is not a fix station. The coordinates are associated with the trajectories of ships. We will need to discuss how we could consider these "mobile" points in GHOST.

Cheers

Sara