겨울철 cP 확장 시 발생하는 Cloud Streets의 레이더 영상 분석

Abstract

When the cold surge of the Siberian anticyclone expands southward during the wintertime, it enforces to produce lower clouds over the yellow sea where often are converted into the cloud streets type and produce heavy snowfall over southwestern coast of the Korean peninsula, Honam Province. On the current study, the formation and development conditions of the cloud streets has been investigated through analysis of the three dimensional snow cloud structures by using the CAPPI, RHI, VAD and VVP data of X-band radar at Muan Weather Observatory and S-band radar at Jindo Weather Station. The data to be used are obtained from January 3 to January 5, 2003, when heavy snow storm hits on the Honam Province. The formation conditions for the cloud street such as the pressure pattern, vertical distribution of temperature, wind velocity /direction, and the strengthening and weakening of the cloud street with these conditions are analyzed. At the beginning of the cloud streets generation stage, these has elongated the band structure of cloud which the horizontal pattern is parallel or perpendicular to the wind direction. Distance between the bands depends on the development stage and ranges from 25km to about 100km. When the cloud street hits over land mass, the horizontal structure begins to break, but vertically develops The PPI radar images show that the cloud band distributes in perpendicular to the expansion direction of the high pressure and that the radius of cloud cells is about 5～8km with 20～30dBZ. Distance between each cell is about 10km. On the other hand, the vertical radar images show that the cloud street is a small scale convective type cloud with height of about 3km where a stable layer exists. From the VVP images, the time period of the high pressure expansion, the moving direction and development stages of the system are delineated. Finally, the vertical distribution of wind direction is fairly constants, while the wind speed sheer increases with altitude. By combining the horizontal and vertical distribution of the meteorological parameters obtained from the radar data and analyses of additional cases, it may be possible to improve the forecast capability of moving direction and future development of the heavy snowfall from the cloud street.