Speaker
Description
Turbulence in clouds is known to enhance particle collision rates which has been demonstrated for warm rain formation. It was often discussed and assumed that a similar effect should also exist for ice processes but so far strong observational evidence for this assumption was missing. We will present the results of a statistical analysis of a 15-month W and Ka band cloud radar dataset which allowed us for the first time to quantify the impact of turbulence on snow aggregation and riming in Arctic low-level mixed-phase clouds. We find that increasing Eddy Dissipation Rate (EDR, derived with mean Doppler velocity time series) correlated with larger snow aggregates revealed by dual-wavelength ratios. In temperature regimes more favourable for riming, higher EDR is associated with dramatically higher particle fall velocities (for same liquid water path category) indicative of markedly higher degrees of riming. The polarimetric observations at Ka band also indicate that ice fragmentation processes are also enhanced by turbulence especially in the temperature region where dendritic particles grow.
| Presenting Author | Stefan Kneifel |
|---|---|
| Email Address of Presenting Author | stefan.kneifel@lmu.de |
| Affiliation of Presenting Author | Ludwig-Maximilians-Universität München |
| Address of Presenting Author | Theresienstr. 37, 80333 München |
| Session | Enhancing Process Understanding: New observations for modeling and parameterization development |
| Preferred Contribution Type | Oral Presentation |
