Tatsuo Endoh

Determination of a Z-R Relationship for Snowfall Using a Radar and High Sensitivity Snow Gauges

Abstract A best-fit power-law relationship (Z = 427 R1.09) between 1-minute integrated averages of snowfall rate (R) and radar reflectivity factor (Z) was determined on the basis of observations made by using high sensitivity snow gauges (accuracy 0.03 mm h−1) and a radar (wavelength 3.2 cm, beamwidth 1.1°) of three 1987 Sapporo snowstorms. The relationship Z = 554R0.88, using 30-minute integrated averages of Z and R, produced the best radar estimate of total snowfall. The ratio of the estimated to the observed amount of snowfall decreased with increasing density of new fallen snow ρ, the ratio roughly equaling 1, when ρ ≈ 0.05 g cm−3.

Influence of the growth mechanism of snow particles on their chemical composition

Abstract Case studies of chemical analysis of solid precipitation were made at sites on the outskirts and central part of Sapporo City, Japan to investigate the difference in precipitation chemistry owing to the mechanism by which snow particles grow, i.e. by vapor deposition or by riming. Even in vapor depositional growth, the samples were found to be acidic. NO 3 − and nss-Cl − contributed to the acidification. In the samples of riming growth, the nss-SO 4 2− concentration was considerably high. Snow samples from the site in the central city area were less acidic due to the higher concentration of nss-Ca 2+ in the early period of snowfalls.

A Vertical Wind Tunnel for Snow Process Studies

Abstract A vertical wind tunnel using an artificially generated supercooled cloud was constructed to study snowfall processes. It is 18 m high and operates to a temperature as low as −25°C. Ultrasonic atomizers supply the supercooled water droplets, and ice crystals are generated by an automated adiabatic expansion of compressed air. The system operation is preprogrammed. Snowfall is sustained for about 20 min after injection of the seed ice crystals. Ice crystals of various forms and sizes including dendritic crystals up to 2 mm in diameter, and snowflakes more than 4 mm in diameter were successfully grown in the tunnel.