The second edition of the International Summer Snowfall Workshop (ISSW) took place in Hyytiälä - Finland (27 – 30 August 2019). 41 people, including the whole OPTIMice group, attended and presented their work (22 posters and 25 talks) at the ISSW which focus was on connecting observations and models. During the talks and poster sessions, we had the opportunity to see the latest developments in snow microphysics, remote sensing and scattering of snow. We also had the chance to see the newest techniques and methods for observing snow at the workshop site (e.g. remote sensing and in situ observation). We, Markus Karrer (MK) and José Dias (JD), presented our work during the poster session.

The work presented by JD described the influence of the snow aggregation in the properties the melting layer, region around 0 C where the snowflakes start melting, observed from a novel radar-setup which an X-, Ka-, and W- band radars. The results of this study suggested that aggregation takes place continuously until the snowflakes reach the melting layer. The results also indicated that in some cases, an extreme aggregation takes place, which increases the thickness of the melting layer increases and enhances the rainfall rate. MK presented his study about the terminal velocity of ice particle inferred by an aggregation model. In this study, we demonstrate that the terminal velocity of ice monomers and aggregates are similar if they are of a similar size and that the monomer type which composes the aggregate determines their terminal velocity.

We thank the Graduate School of Geosciences for the support, which made it possible to participate in this exciting workshop!

José Dias Neto
PhD student
Institute of Meteorology
PhD project: “Investigating Microphysical processes in ice and snow clouds using novel combination of polarimetric and multi-frequency cloud radars” 
Intense aggregation close to melting layer observed with triple-frequency radars (Poster)

Markus Karrer
PhD student
Institute of Meteorology
PhD project: “Improving the Representation of Ice Microphysical Processes in Numerical Models by Comparison with Radar Observations”
Terminal Velocity of Unrimed Ice Particle Simulated with an Aggregate Model and Hydrodynamic Theory (Poster)