ACDL/DQ-1 measurements of global cloud heights and geometric thickness: results and intercomparison with CALIOP products

Accurate knowledge of the vertical distribution of clouds is crucial for quantifying cloud-radiative effects, constraining climate feedbacks, and improving weather prediction. Spaceborne lidars provide an effective means of observing global cloud profiles. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), one of the most influential instruments to date, delivered benchmark-quality cloud observations from 2006 until its decommissioning in 2023. The Aerosol and Carbon Detection Lidar (ACDL), onboard China’s DQ-1 satellite launched in April 2022, represents a promising successor with enhanced capabilities. This study presents the first comprehensive global assessment of cloud top height (CTH), cloud base height (CBH), and cloud geometric thickness (CGT) using ACDL data. We examine the global distribution and variability of these cloud properties in relation to seasonal cycles and cloud phase. A comparison with CALIOP measurements during their one-year overlap reveals expected agreement between the two datasets on a global scale. For collocated observations of cloud heights, the correlation coefficients exceed 0.94, with root mean square errors below 1.3 km. These results highlight ACDL’s strong potential to carry forward the legacy of global cloud monitoring and to contribute to long-term climate observations.