High-resolution observations of precipitation from cumulonimbus clouds

Making high-resolution observations of heavy rainfall from cumulonimbus clouds involves choosing a good location where convection occurs frequently and with some degree of predictability so that aircraft do not have to chase clouds, and radars and other ground-based instruments can be optimally placed. It also requires significant resources, international collaboration and a good deal of serendipity. This paper describes several observational campaigns that were designed to understand relatively small-scale convective clouds that produce heavy precipitation, and presents results that have been found over the years. It complements the companion papers in this special issue by giving an observational perspective. It is by no means comprehensive and is limited to cumulonimbus clouds. The Convective Storm Initiation Project (CSIP) was designed to understand the phenomena responsible for the initiation of convection in the maritime environment of southern England. There was a similar objective in the Convective Orographically-induced Precipitation Study (COPS), but for the complex terrain of the Black Forest mountains, Germany, and the Vosges Mountains, France. The recent Convective Precipitation Experiment (COPE) was designed to understand the entire life cycle of convective clouds that formed along sea-breeze convergence lines in the southwestern peninsula of England. Its particular focus was on the dynamics and microphysics of the convective clouds. Examples of observations from these and other field campaigns designed to study the initiation of convection, cumulonimbus clouds and convective precipitation are presented, with a view to demonstrating how they contribute to a physical understanding of the phenomena and the processes involved.