Global cloud-layer distribution statistics from 1 year CALIPSO lidar observations

Abstract

In this paper, the cloud statistics and global cloud distributions are derived from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level 2, 5 km lidar cloud-layer products between 13 June 2006 and 24 June 2007. The global cloud-layer occurrence frequency, the horizontal and the vertical distributions of cloud-occurrence frequency, the global cloud-top height statistics and their seasonal changes are given for 1 year CALIPSO observations. Opaque cloud-layer statistics are analysed for better understanding the statistics of the clouds observed using CALIPSO. Parts of the results are compared with some results from the High Resolution Infrared Radiation Sounder (HIRS) observations, the Geoscience Laser Altimeter System (GLAS) observations and the global rawinsonde observations, the Aqua MODerate Resolution Imaging Spectroradiometer (MODIS) monthly cloud-fraction data. The comparisons show that results are in agreement with other observations. Due to the primary advance from the active optical sensing, CALIPSO lidar can offer measurements of accurate, highly resolved vertical profiles of atmospheric scattering layers. It has advantages in determining the location of optically thin clouds and detecting occurrences of multiple layers. Long-term observations by CALIPSO lidar can provide valuable information for the better understanding of the climate system and global climate change.

Acknowledgements

This study was supported by the Multi-Instrument Data Analysis and Synthesis (MIDAS) project of NASA's Radiation Science Program. The authors wish to thank the CALIPSO team at NASA Langley Research Center for providing the data used in this paper. Parts of the study by the first author were carried out in the Center for Atmospheric Sciences of Hampton University while a visiting Scholar and supported by the China Scholarship Council.