Challenges for cloud modeling in the context of aerosol-cloud-precipitation interactions

The International Cloud Modeling Workshop (CMW) has been a longstanding tradition in the cloud microphysics modeling community and is typically held the week prior to the International Conference on Clouds and Precipitation (ICCP). For the Ninth CMW, more than 40 participants from 10 countries convened at the Met Office in Exeter, United Kingdom. The workshop included four detailed case studies (described in more detail below) rooted in recent field campaigns. The overarching objectives of these cases were to utilize new observations to better understand intermodel differences and model deficiencies, explore new modeling techniques, and gain physical insight into the behavior of clouds. As was the case at the Eighth CMW, there was a general theme of understanding the role of aerosol impacts in the context of cloud–precipitation interactions. However, an additional objective was the focal point of several cases at the most recent workshop: microphysical–dynamical interactions. Many of the cases focused less on idealized small-domain simulations (as was the general focus of previous workshops) and more on large-scale nested configurations examining effects at various scales. The CMW provides a forum for detailed discussion within the community on current issues, and this was further emphasized at the Ninth CMW. The workshop was framed around the four cases described below in which all participants were encouraged to participate in discussion. There were also several plenary talks discussing novel modeling techniques and advancements in cloud modeling. The interaction among the participants resulted in a sometimes lively discussion, several key outcomes, and a clear direction for further advancing the state of the science.