Fragmentation in Collisions of Snow with Graupel/Hail: New Formulation from Field Observations
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden, Institute for Atmospheric Physics, Johannes Gutenberg University, Mainz, Germany
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden, Institute of Meteorology and Climate Research, Troposphere Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden, Atmospheric Research Centre of Eastern Finland, Finnish Meteorological Institute, Kuopio, Finland
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden, Department of Ecoscience, Aarhus University, Roskilde, Denmark
- Unit for Field-Based Forest Research, Swedish University of Agricultural Sciences, Vindeln, Sweden
- National Center for Atmospheric Research, Boulder, Colorado
Secondary ice production (SIP) has been attributed to the generation of most ice particles observed in precipitating clouds with cloud tops warmer than −36°C, from various aircraft- and ground-based field observations across the globe. One of the known SIP mechanisms is fragmentation during collisions among ice particles. It has been studied with our theoretical formulation, which has been applied in microphysical schemes of atmospheric models in a few studies. These have predicted an extensive impact on cloud glaciation and radiative properties. However, there has been a lack of experimental field studies, especially involving naturally falling snowflakes, to better understand this particular mechanism of SIP. This study reports the first field measurements with modern technology for fragmentation during collisions between naturally falling snowflakes and graupel/hail particles. This was observed with an innovatively designed portable chamber that was deployed outdoors in northern Sweden. Applying the observations from this field-based study, we optimized the existing formulation for predicting numbers of fragments from collisions of snow with graupel/hail. The observations show the average numbers of fragments per collision for dendritic (3–12 mm) and nondendritic (1–3 mm) snow were about 12 and 1, respectively. This represents a boost of predicted fragment numbers relative to our original formulation published in 2017. The updated formulation for breakup in ice–ice collisions can be implemented in the microphysical schemes of atmospheric models.
- Research Organization:
- ARM Data Center, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- Sweden’s Innovation Agency; Swedish Research Council for Sustainable Development; USDOE; USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Contributing Organization:
- PNNL, BNL, ANL
- Grant/Contract Number:
- SC0018932; SC0018967
- OSTI ID:
- 2482606
- Alternate ID(s):
- OSTI ID: 2503500
- Journal Information:
- Journal of the Atmospheric Sciences, Journal Name: Journal of the Atmospheric Sciences Journal Issue: 12 Vol. 81; ISSN 0022-4928
- Publisher:
- American Meteorological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English