The Tropical phase of the Ice in Clouds Experiment (ICE-T) is planned for the summer of 2011 in the Caribbean. The overarching goal of these aircraft field experiments is to determine whether out-of-cloud aerosol measurements can predict cloud ice in tropical mixed-phase clouds. Measurements of cloud condensation nuclei (CCN) spectra will be crucial for ICE-T field experiment.
In tropical clouds the production of cloud ice depends more heavily on the liquid/warm phase, which is especially prominent in warm, humid environments where cloud bases are low. Ice production by direct and secondary processes is hypothesized to depend on droplet and drop size spectra. More active warm rain processes are thought to enhance ice production; that is large cloud drops tend to promote both warm precipitation and the production of ice. It is well accepted that liquid cloud microphysics depends on the input aerosol - namely CCN.
Intellectual merits. In this study, we will conduct both in-situ sampling and post experiment analysis of data taken with two Desert Research Institute's (DRI, University of Nevada) cloud condensation nuclei (CCN) spectrometers during the upcoming ICE-T field campaign. The DRI's CCN spectrometers can provide more complete CCN spectra at high temporal and supersaturation resolution than other available CCN probes. One unique feature of the DRI CCN spectrometers is their wide range of operational supersaturations. Simultaneous measurements of large and giant nuclei, activated at very low supersaturatons (<0.001%), are of particular importance for the relatively clean tropical ocean environment in which ICE-T will be conducted.
The DRI CCN spectrometers will provide not only detailed, accurate, and complete spectra necessary for such an important endeavor, but they also provide supplementary volatility and CCN size measurements. These additional efforts afford important clues about CCN compositions and origins, which may also provide understandings on how dust and biomass burning affects the ICE-T clouds.
Broader Impacts. The measurements of full CCN spectrum are critical for studies on fundamental cloud physics. The data obtained from ICE-T will be available to the scientific community for further analysis and use, such as in modeling studies. The measurements of composition and origin of CCN may have broader implication in studying aerosol and cloud interactions and climate research.
The project will support training of a graduate student. The student will gain valuable learning experience by participating in the field project, as well as involving in subsequent analysis and preparation of scientific manuscripts.
