"LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies” (LIVAS) is an ESA project aiming to provide a global and extensive aerosol and cloud optical database, to be used for current and future space-borne lidar end-to-end simulations of realistic atmospheric scenarios, as well as retrieval algorithm testing activities. LIVAS provides a global 3-dimensional aerosol and cloud optical climatology and a collection of case studies focused on atmospheric episodes related to specific aerosol/cloud types (extended atmospheric scenes, i.e. Saharan dust events, smoke and volcanic eruption events, polar-stratospheric clouds etc). In order to cover the different spectral domains for HSRL and IPDA lidars, the compiled database addresses the three harmonic operating wavelengths of Nd-YAG lasers (355 nm, 532 nm and 1064 nm) as well as typical wavelengths of IPDA lidars in the SWIR spectral-domain (1570 nm and 2050 nm).