loading page

Ice Particle Properties Inferred from Aggregation Modelling
  • +3
  • Markus Konrad Karrer,
  • Stefan Kneifel,
  • Davide Ori,
  • Christoph Siewert,
  • Axel Seifert,
  • Annakaisa von Lerber
Markus Konrad Karrer
Institute of Geophysics and Meteorology, Institute of Geophysics and Meteorology

Corresponding Author:markus.karrer@uni-koeln.de

Author Profile
Stefan Kneifel
University of Cologne, University of Cologne
Author Profile
Davide Ori
Institute for Geophysics and Meteorology, Institute for Geophysics and Meteorology
Author Profile
Christoph Siewert
Deutscher Wetterdienst, Deutscher Wetterdienst
Author Profile
Axel Seifert
Deutscher Wetterdienst, Deutscher Wetterdienst
Author Profile
Annakaisa von Lerber
Finnish Meteorological Institute, Finnish Meteorological Institute
Author Profile


We generated a large number (105’000) of aggregates composed of various monomer types and sizes using an aggregation model. Combined with hydrodynamic theory, we derived ice particle properties such as mass, projected area, and terminal velocity as a function of monomer number and size. This particle ensemble allows us to study the relation of particle properties with a high level of detail which is often not provided by in-situ measurements. The ice particle properties change rather smoothly with monomer number. We find very little differences in all particle properties between monomers and aggregates at sizes below 1 mm which is in contrast to many microphysics schemes. The impact of the monomer type on the particle properties decreases with increasing monomer number. Whether e.g., the terminal velocity of an aggregate is larger or smaller than an equal-size monomer, depends mostly on the monomer type. We fitted commonly used power laws as well as Atlas-type relations, which represent the saturation of the terminal velocity at larger sizes, to the dataset and tested the impact of incorporating different levels of complexity with idealized simulations using a 1D Lagrangian super-particle model. These simulations indicate that it is sufficient to represent the monomer number dependency of ice particle properties with only two categories (monomers and aggregates). The incorporation of the saturation velocity at larger sizes is found to be important to avoid an overestimation of self-aggregation of larger snowflakes.
Aug 2020Published in Journal of Advances in Modeling Earth Systems volume 12 issue 8. 10.1029/2020MS002066