Objective Estimates of Airborne Snow Properties

View More View Less
  • 1 Geochemical Sciences Branch, U.S. Army Research and Engineering Laboratory, Hanover, New Hampshire
© Get Permissions
Restricted access

Abstract

A mensuration and description method is proposed that allows objective and simultaneous expression of the physical properties of snow crystals, rime drops, and aerosol particles. It is based on the statistics of Hatch and Choate, which are commonly used to describe “dusts” and supermicrometer aerosol particles with irregular shape. These statistics simplify integration of physical properties of snowflakes over their diameter distribution and facilitate expression of simultaneous formulas that can be used to calculate the contribution of riming to airborne snow mass and the contribution of rime nuclei to airborne snow chemistry.

These formulated expressions are combined with tabulations of size properties of snowflakes, cloud droplets, and aerosol to provide the skeleton of a calculation program. These calculations can transform the area, mass, or number concentration of snow fluxes into other parameters when one flux parameter and the snow-crystal habit are specified. Other size-dependent parameters are easily inserted in this skeleton to facilitate estimation of physical properties of suspended snow.

The cross-sectional area-to-mass ratio of airborne snow, with respect to the distribution of particle diameters, is relatively large when compared to liquid precipitation particles. The cross-sectional area-to-mass ratio provides an objective parameter for comparison of snowflake properties with respect to crystal type. Several figures are presented that show the variation of airborne snow area, mass contribution by rime, and snow chemistry as a function of crystal type and diameter distribution.

Abstract

A mensuration and description method is proposed that allows objective and simultaneous expression of the physical properties of snow crystals, rime drops, and aerosol particles. It is based on the statistics of Hatch and Choate, which are commonly used to describe “dusts” and supermicrometer aerosol particles with irregular shape. These statistics simplify integration of physical properties of snowflakes over their diameter distribution and facilitate expression of simultaneous formulas that can be used to calculate the contribution of riming to airborne snow mass and the contribution of rime nuclei to airborne snow chemistry.

These formulated expressions are combined with tabulations of size properties of snowflakes, cloud droplets, and aerosol to provide the skeleton of a calculation program. These calculations can transform the area, mass, or number concentration of snow fluxes into other parameters when one flux parameter and the snow-crystal habit are specified. Other size-dependent parameters are easily inserted in this skeleton to facilitate estimation of physical properties of suspended snow.

The cross-sectional area-to-mass ratio of airborne snow, with respect to the distribution of particle diameters, is relatively large when compared to liquid precipitation particles. The cross-sectional area-to-mass ratio provides an objective parameter for comparison of snowflake properties with respect to crystal type. Several figures are presented that show the variation of airborne snow area, mass contribution by rime, and snow chemistry as a function of crystal type and diameter distribution.

Save