Gorow Wakahama

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.

On Snow Particles Comprising an Aggregate

Abstract Types, degree of riming and size of snow particles comprising aggregates from snow bands were investigated. From the data obtained, the microphysical processes which control the precipitation intensity were elucidated. The results are summarized as follows: 1) Snow particles comprising aggregates were classified into three types: nonrimed or lightly rimed snow crystals; rimed or heavily rimed snow crystals having discernible snow crystals prior to riming; and heavily timed or graupel-like snow particles. 2) Nonrimed or lightly rimed snow crystals occupied about 30% of the total number of snow particles comprising an aggregate when precipitation intensity (R) was very intense (>5 mm h−1). 3) Regardless of the intensity of precipitation, there were no apparent differences in size distribution of snow particles. 4) Although the cloud depth was larger when R > 5 mm h−1 than when R 5 mm h−1. 5) Graupel-like particles...

Investigations of internal structure and transformational processes from firn to ice in a perennial snow patch.

To investigate the internal structure and transformational processes from firn to ice of the Hisago snow patch on Daisetsu Mountain, Hokkaido, Japan, many drillings were made during the ablation period in 1986 and 1987. The ice cores were analyzed for stratigraphy, density and free water content. The internal structure of the snow patch was characterized by a wet firn layer with abundant ice layers and ice glands overlying a 4.3 m-thick ice body. The thickness of the firn layer varied from 12.7 m inJune to 1.3 m in October. A water-saturated firn layer about 1 m thick existed just above the firn-ice transition. The annual layers were identified by dirt layers which showed that 1-2 m of ice was formed each year when the mass budget was positive. Although the densification of the water-saturated firn layer proceeded rapidly, the transformation from firn to ice could not be recognized during the ablation period. It was concluded that the formation mechanism of the ice body comprised three processes: the formation of superimposed ice, the densification of a water-saturated firn layer and the freezing of wet and/or water-saturated firn by cold wave penetration.

Three-Dimensional Display of Radar Echoes Using the Technique of Marching Cubes

Abstract We present three-dimensional (3D) displays of meteorological radar echoes. We made surfaces of precipitating clouds specified by some echo intensity (dBZ) by the marching cubes method, which is a high-resolution 3D surface construction algorithm. Surfaces of radar echoes look like “real” surfaces of clouds and give a good insight into their 3D configuration.

Crystallographic orientation of a recrystallized grain grown in a strained single crystal of ice

Abstract A rectangular solid sample, made from a single crystal of ice, with a grid of grooves cut on its top face, was uniaxially compressed and then annealed to allow recrystallization. Crystallographic orientations were determined by the transmission Laue method, and additional studies were made of the orientation distribution of the recrystallized grains and the growth process. Many fine grains recrystallized at the grooved face at the beginning of annealing but only a few grew into large grains invading the lower portion of the crystal on continued annealing. Although the fine grains were randomly oriented, the large grains appeared to show some preferred orientation to the 〈0001〉 axis of the matrix. The results are interpreted using a kinetic theory of recrystallization.

Growth steps on an ice crystal grown from the vapour

Abstract Growth steps on the {0001} and {10T0} faces on an ice crystal grown from the the vapour have been observed by differential interference microscopy. The height of the steps has been measured by multiple-beam interferometry.