Prospects for long-term lidar cloud observations

Long-term observations of the atmosphere are required to understand the earth's climate and its variability. The utility of the long-term observations of clouds is explored in this paper. Several national and international experiments have shown that such observations are feasible, and the resultant scientific benefits make them desirable. Scientific requirements are discussed in terms comprehensive statistics of cloud amount, base height and depth, optical depth and microphysics, including cloud phase and effective radius. The instrumental requirements to measure the above quantities are described, indicating the increased instrumental sophistication that is required for the more detailed observations.