Assessing Snowfall Rates from X-Band Radar Reflectivity Measurements

Abstract Realistic aggregate snowflake models and experimental snowflake size distribution parameters are used to derive X-band power-law relations between the equivalent radar reflectivity factor Ze and the liquid equivalent snowfall precipitation rate S (Ze = ASB). There is significant variability in coefficients of these relations caused by uncertainties in the snowflake bulk densities (as defined by the mass–size relationships), fall velocities, and particle size distribution parameters. The variability in snowflake parameters results in differing Ze–S relations that provide more than a factor of 2 difference in precipitation rate and liquid equivalent accumulation estimates for typical reflectivity values observed in snowfall (∼20–30 dBZ). Characteristic values of the exponent B in the derived for dry snowfall relations were generally in the range 1.3–1.55 (when Ze is in mm6 m−3 and S is in mm h−1). The coefficient A exhibited stronger variability and varied in the range from about 30 (for aircraft-b...