Abstract
The radar echo analysis in which the heavy snowfall intensity stronger than 6cmh-1 in snow depth was recorded on the lower elevation angle of radar scanner was carried out from the viewpoint of traffic transport facilities and localized heavy snowfall phenomena on the Ishikari Plain including Sapporo, Hokkaido, Japan. From the analysis of radar echo, it was clarified that there were high frequency areas. Furthermore, it was understood that there were some areas with sudden changes in snowfall intensity stronger than 10 cmh-1 in a limited few km2 in a horizontal scale and 10 minute duration in calm weather condition. Vertical cross section analyses across the abnormal heavy snowfall areas in which there were recorded with an intensity stronger than 6 cmh-1 by radar showed that the drastic increase of snowfall intensity occurred between 200m and 400m above the ground surface. The change of the maximum value of the radar echo intensity at around 200m level was estimated by the growth of large snowflakes which were aggregated and formed quickly under the horizontal and vertical wind shears at the same level.
