Study on the characteristics of cloud base height detected by spaceborne lidar

This paper presents a comprehensive statistical analysis of cloud characteristics derived from spaceborne lidar observations, with a particular focus on the spatiotemporal variations of cloud layers and the lowest cloud base height (CBH) over oceanic regions. Utilizing three years (January 2019-December 2021) of CALIPSO satellite data, this study systematically examines the occurrence probability of various cloud layers and the temporal-spatial distribution patterns of CBH within the study area (4-22°N, 106-120°E). The research reveals that: (a) The diurnal and nocturnal occurrence probability trends of different cloud layers exhibit consistent patterns, with clear sky and single-layer clouds dominating (accounting for approximately 80% of all observed conditions), while multi-layer cloud occurrences remain consistently below 5%; (b) Cloud base height demonstrates significant seasonal variations, following a sine-like pattern where the average CBH gradually increases during spring, reaches its peak in summer, and subsequently decreases during autumn and winter, with the minimum value occurring in winter; (c) Spatially, the study area exhibits a persistent “south-high, north-low” pattern, with particularly elevated CBH values observed over waters northeast of Palawan Island and northern Malaysia, often exceeding 9,000 meters. These findings provide critical insights for marine hazardous weather monitoring, navigation safety assurance, and climate change research, offering valuable reference for China's oceanic atmospheric observation initiatives.