A new formulation for interpreting heterogeneous ice nucleation data

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Thursday, 8 January 2015: 4:45 PM
223 (Phoenix Convention Center - West and North Buildings)
Hassan Beydoun, Carnegie Mellon University, Pittsburgh, PA; and R. C. Sullivan

Heterogeneous ice nucleation in tropospheric clouds remains one of the outstanding problems in cloud physics and atmospheric science. Our lack of understanding ranges from inadequacies in theoretical understanding of the ice nucleation process, to challenges in experimentally controlling and observing simulations of these processes.

A minimalist ice nucleation parameterization has been developed for potentially facile application in atmospheric models. The formulation is based on classical nucleation theory and reduces the problem of heterogeneous ice nucleation to two basic statistical parameters. Numerical trials with the parameterization reconcile between observed singular and stochastic behavior by showing that the controlling factor is merely a consequence of the conditions set forth by the experimentalist. The new framework succeeds at fitting published results obtained with short and long time scale experiments more rigorously than traditional approaches and without invoking too many additional parameters. We also applied the new parameterization to fit our recent heterogeneous ice nucleation data from optical tweezers and droplet freezing on a cold plate experiments. The effort is motivated by the crucial need to provide atmospheric models with better information to describe ice nucleation processes in a unified and consistent manner.