资源环境科技发展态势分析平台

During the 2012 Changma season of June and July, we conducted an intensive field observation to investigate the microphysical characteristics of orographic precipitation that passed around Mt. Halla (oriented west-east; height: 1950 m; width: 78 km; length: 35 km) in South Korea's Jeju Island. On July 04, 2012, Jeju Island experienced a convective precipitation system that developed in the southern part of a stationary front. With the goal of understanding the microphysical process of this system (precipitation intensity: 70 mm h(-1)), we collected detailed data using 7 Parsivel disdrometers, a ground-based dual S-band Doppler radar, and GPS sounding. The convective precipitation developed in a considerably warm and moist environment (near-surface relative humidity: 94%) with dominant southwesterly winds of 4.7 m s(-1). at low altitudes. The convective region was formed by a combination of coastal ascending air and considerably warm and moist low-level marine inflow. The coastal warm and moist ascending air activates the warm rain process of moisture uptaken from sea surface, increasing the concentration of large-sized raindrops (diameter: >= 5 mm). The continuous development of a convective region extending from the foothill to the upslope highlights that the convective updrafts continuously supply low-level moisture to the convective region. This influx of moisture and the condensation of small-, middle-, and large-sized raindrops combine to create a significant concentration of large-sized raindrops along the upslope of the mountain. Around the mountaintop, the fall of precipitation drives the breakup process aided by convective ascending airs, increasing the concentrations of small-sized raindrops. On the leeward side, the existence of orographically generated stationary wind convergences is notable, As a result and the marine inflow along the southeastern gentle slope, i.e., the convective region, continues to develop, thereby activating cold rain processes. This study sheds light on the variety of raindrop size distributions and moisture processes at locations relative to a single-peak mountain leading to localized heavy precipitation during the passage of an isolated convective precipitation event.