The high variability of tropospheric aerosols, both in space and time, is the main cause of the high uncertainty about radiative forcing related to tropospheric aerosols and their interaction with clouds. Because of the lack of high resolution aerosol global vertical profiles, the vertical mixing has not been considered so far in studies of spatial and temporal variability. The CALIPSO mission provides the first opportunity to investigate the 4-D aerosol and cloud fields in detail. However, because of the CALIOP small footprint and the revisit time of 16 days, correlative ground-based lidar observations are necessary in order to investigate the representativeness of these satellite observations. EARLINET, the European Aerosol Research Lidar Network, started correlative measurements for CALIPSO in June 2006, right after the CALIPSO launch. An integrated study of CALIPSO and EARLINET correlative measurements opens new possibilities for spatial (both horizontal and vertical) and temporal representativeness investigation of polar-orbit satellite measurements also in terms of revisit time.