07/05/2011
Improved Ice Particle Measurements
Summary
Understanding the formation and evolution of small ice particles in clouds has been a long-standing issue in cloud physics. Improving measurements of ice particles is critical for improving the predictive capabilities in the models since small ice particles (less than 100 microns) may play a significant role in radiation transfer and precipitation formation. In an effort to improve understanding of ice particles in clouds, the Atmospheric Radiation Measurement Climate Research Facility, a DOE scientific user facility, recently completed the Small Particles in Cirrus (SPartICus) experiment to examine cirrus clouds. A central focus was to address the challenging problem of large ice particles shattering on the inlets and tips of cloud particle probes, a process that produces copious ice particles that can be mistakenly measured as real ice particles. Currently, two approaches are being used to mitigate the problem: (1) redesigned probe tips and (2) improved post processing techniques. Results from SPartICus show that modified probe tips significantly reduce the number of shattered particles, but that a new particle arrival time algorithm is even more effective than the redesigned probe tips in giving accurate ice particle measurements. The analysis techniques in this paper can also be used to estimate an upper bound for the effects of shattering. This new technique provides an enhanced tool for characterizing the properties of clouds so that their representation can be improved in global climate models.
References
Lawson, R. P. 2011. “Effects of Ice Particles Shattering on the 2D-S Probe,” Atmospheric Measurement Techniques 4, 1361-81. DOI: 10.5194/ amt-4-1361-2011.