11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Tuesday, 4 June 2002
Further analysis and improvements of ice crystal mass-size relationships
Brad Baker, SPEC, Inc., Boulder, CO; and C. Schmitt, P. Lawson, and D. Mitchell
Poster PDF (241.1 kB)
Mitchell et al. 1990* presents a study of ice crystal mass size relationships. Crystal maximum dimension and mass were measured. Linear regression analysis was performed on the data to estimate an average mass size relationship. Relationships were determined for subsets of the data set based on crystal habit as well as for the full data set.

The errors (100 X [estimate-actual]/[actual]), for individual crystals, tended to be large (mean on order of 50%). However the assumption implicit in using the relationships is that when applied to a large enough group of crystals the errors cancel. That is, the relationship is assumed accurate on average. We explore the validity of this assumption via a bootstrap style analysis and thus test the robustness of using the individual, habit conditioned, relationships as opposed to using a single relationship for all crystal types. We find that the individual relationships are not robust enough to warrant their use.

We reanalyze the Mitchell data to explore the possibility of improving these relationships by using more than maximum dimension to represent the crystal sizes. For example, area and perimeter can now be calculated with automatic image processing software.

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