The Ice in Clouds Experiment (ICE) is a multi investigator project with the intent to better understand the process of ice initiation in the atmosphere. As a first step in this investigation, the involved participants will focus on dynamically simple systems. They will study high altitude, layer clouds (hence ICE-Layer Clouds or ICE L) where the relationship between aerosols and ice production will be relatively simple compared to other cloud systems.
As part of the ICE L, the PI will obtain cloud condensation nuclei (CCN) observations and utilize these to address research problems of relevance to ICE-L and other scientific objectives. In essence, to understand the ice production in any cloud system, one must understand all phase transitional processes, including those that involve CCN. This includes the impact of CCN on condensational processes and in such areas as immersion nucleation. In addition to contributing to better general understanding of the microphysical processes in the layer clouds, the PI will investigate the maximum supersaturation in these systems (not previously done) and investigate the mass accommodation coefficient in these dynamically simple systems.
To accomplish the research objectives, the PI will deploy on the NSF C 130 research aircraft an instrument to observe the CCN spectra. This and other collaborative observations will allow the PI to attack his research objectives. These measurements include fine spatial resolution as well as good supersaturation (S) resolution of both the traditional Aitken CCN range (< 0.1 micron dry soluble diameter) and the large nuclei range (0.1-1 micron). This full range of S available only with the DRI instruments is necessary to ascertain relationships between CCN and IN measurements. CCN measurements can also aide in discriminating the different modes of ice nucleation because some of the modes-homogeneous, condensation freezing, and immersion-freezing directly involve CCN.
The ice process has important implications for a broad range of atmospheric topics from precipitation production to climate issues including the indirect aerosol effect, which is one of the most important unknowns of climate feedback processes.
