Articles | Volume 9, issue 9
Atmos. Meas. Tech., 9, 4825–4841, 2016
Atmos. Meas. Tech., 9, 4825–4841, 2016

Research article 28 Sep 2016

Research article | 28 Sep 2016

Ensemble mean density and its connection to other microphysical properties of falling snow as observed in Southern Finland

Jussi Tiira1, Dmitri N. Moisseev1,2, Annakaisa von Lerber2,3, Davide Ori1,4, Ali Tokay5,6, Larry F. Bliven7, and Walter Petersen8 Jussi Tiira et al.
  • 1Department of Physics, University of Helsinki, Helsinki, Finland
  • 2Finnish Meteorological Institute, Helsinki, Finland
  • 3School of Electrical Engineering, Aalto University, Finland
  • 4Department of Biological Geological and Environmental Sciences and Department of Physics and Astronomy, University of Bologna, Bologna, Italy
  • 5Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, USA
  • 6NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 7NASA GSFC/Wallops Flight Facility, Wallops Island, VA, USA
  • 8NASA-MSFC Earth Science Office, National Space Science and Technology Center, Huntsville, AL, USA

Abstract. In this study measurements collected during winters 2013/2014 and 2014/2015 at the University of Helsinki measurement station in Hyytiälä are used to investigate connections between ensemble mean snow density, particle fall velocity and parameters of the particle size distribution (PSD). The density of snow is derived from measurements of particle fall velocity and PSD, provided by a particle video imager, and weighing gauge measurements of precipitation rate. Validity of the retrieved density values is checked against snow depth measurements. A relation retrieved for the ensemble mean snow density and median volume diameter is in general agreement with previous studies, but it is observed to vary significantly from one winter to the other. From these observations, characteristic mass–dimensional relations of snow are retrieved. For snow rates more than 0.2 mm h−1, a correlation between the intercept parameter of normalized gamma PSD and median volume diameter was observed.

Short summary
In this study winter measurements collected in Southern Finland are used to document microphysical properties of falling snow. It is shown that a new video imager can be used for such studies. Snow properties do vary between winters.