Towards Establishing a Long-Term Cloud Record from Space-Borne Lidar Observations

Clouds play a crucial role in the Earth’s energy budget, but their feedback is still uncertain. A thorough grasp of clouds, encompassing their cover, vertical arrangement, and optical characteristics, is vital for comprehending and predicting the Earth's energy balance and climate. Satellite observations have been providing a continuous monitoring of clouds, with active sounders being of particular importance because of their vertical and horizontal resolution and accuracy. But, comparing the clouds retrieved from different space-borne lidars is challenging because of differences in wavelength, pulse energy, detector type, local time of overpass, and so on. This study presents an approach to merge clouds measured by the space-borne lidar ALADIN/Aeolus (355 nm), with clouds retrieved from the CALIPSO lidar observations (532 nm). The method involves compensating for the instrumental differences to attain comparable cloud datasets. This sets a path for integrating future lidars, such as ATLID/EarthCare, into the global lidar cloud record.