Modification of Convective Snow-Clouds in Landing the Japan Sea Coastal Region

Abstract

The modification process of convective snow-clouds in landing the Japan Sea coastal region was observed quantitatively by a RHI radar which was set at Wajima in the Noto Peninsula. The analysis of observational data-was made mainly for snow-clouds in two cases of A and D-in case A the outbreak of cold air became intensive with time after the passage of a low pressure and in case D it was predominant persistently.In both cases most of convective radar-echoes which travelled from the sea showed two stages of variation of echo structure in their landing. In the first stage the echo becomes intensive in its center before landing. Its most intensive part descends several kilometers offshore and the other part found out in its frontal side extends upward with time. The latter part descends inland rapidly after having crossed over the seashore. In the second stage seen after landing the intensity of the echo increases gradually again as a diffused broad echo. In the first stage graupels were observed on the ground predominantly and in the second stage snowflakes were observed as predominant particles. It was suggested from the comparison of echo intensity over the sea with that over the land that the amount of snowfall seen in the seaside of the peninsula was larger than that in the land side in case D, while it was smaller than that in the land side in case A.

Three-Dimensional Radar Echo Structure of a Snow Band Formed on the Lee Side of a Mountain

“…This is also the reason why graupel is predominantly observed near the sea coast. This process was also discussed by Takeda et al (1982).…”

Doppler Radar Study on the Successive Development of Snowbands at a Convergence Line near the Coastal Region of Hokuriku District

“…Many previous studies have noted that the modification of snow clouds before landing plays an important role in the precipitation features in the downwind region (e.g., Isono et al 1966a and b;Takeda et al 1982;Murakami et al 1994;Saito et al 1996). Modifications of convective clouds near the coast are popular phenomena, and are reported in many other regions (e.g., Hsu 1988;Braun et al 1997;Kanada et al 1999).…”

Doppler Radar Analysis of the Structure of Mesoscale Snow Bands Developed between the Winter Monsoon and the Land Breeze

“…During the period from 1962 to 1967, a research field experiment known as the Heavy Snowfall Research Project, was carried out by the Japan Meteorological Agency (JMA), and the synoptic and mesoa scale (200-2000km) mechanisms of the snowfall were discussed (Ninomiya, 1964;Matsumoto et al, 1967). Later, using conventional radar and satellites, structural studies of various kinds of mesoscale snow clouds were made (Miyazawa, 1967;Magono, c1989, Meteorological Society of Japan 1971; Shimizu and Uchida, 1974;Asai and Miura, 1981;Takeda et al, 1982). Until recently, however, the limitation of observational systems prevented the study of the detailed structure of these mesoscale systems and from understanding their formation and maintenance mechanisms.…”