Re-evaluating observational constraints on depositional ice growth in cirrus clouds
with Dr. Kara Lamb Associate Research Scientist at Columbia University in the Department of Earth and Environmental Engineering.
Cirrus clouds play a significant role in the Earth’s radiation budget, and act as important controls on the distribution of water vapor in the upper troposphere and lower stratosphere. The habits and growth rates of ice crystals in cirrus clouds are known to sensitively depend on temperature, pressure, and supersaturation. However, the surface effects controlling depositional ice growth are complex, and challenging to characterize experimentally. This lack of clear physical understanding limits our ability to model ice crystal habits and growth rates in atmospheric models. While there has been an increasing availability of experimental and observational data from laboratory and in situ measurements that can be used to constrain ice microphysical processes, different methods provide disparate sources of information. In situ observations from aircraft and balloon platforms provide detailed local information, but only at single snapshots in time, in limited sampling conditions, and without growth time-scales. While laboratory experiments allow ice growth to be monitored over time, previous depositional ice growth studies have indicated significant discrepancies between single crystal experiments and larger scale cloud chamber experiments that more realistically simulate atmospheric conditions. Here I will discuss how single crystal and cloud chamber studies can be reconciled, using the same ice growth theory. I will discuss progress towards combining many past in situ observations to reduce structural uncertainty in physics-based models of depositional ice growth. Finally, I will discuss how methods such as reduced order modeling can be used to efficiently represent complex cloud microphysical processes in a simplified manner in larger scale models.
The Earth Science Colloquium Series, sponsored by Lamont-Doherty Earth Observatory and Columbia University Department of Earth and Environmental Sciences (DEES), provides a lively forum for discussing a wide variety of topics within the Earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO. Colloquium attendance is required of all pre-orals DEES graduate students. The Colloquium Series supports the Lamont Seminar Diversity Initiative.