Clear night aerosol profile - FRAM data analysis

To our current knowledge, FRAM will provide us with the integrated atmospheric optical depth (aod) in several cells over a wide field of view (~20x20 deg). The aod contribution of the purely molecular atmosphere (Rayleigh scattering and molecular absorption(?)) will have been already subtracted from FRAM data. Which means that the received aod value corresponds only to aerosols & clouds distribution. Now, a clear night should also have some, albeit small, contribution from aerosols. The following questions should be addressed:

• Should we consider having a clear night aerosol profile per site when LIDAR data are not available?
• If yes, is this profile seasonal?
• Do we consider it stable over the observation block (and thus part of the slow component?)
• When LIDAR data are available, are they automatically override the clear night aerosol profile?
• What is its integral aod?