During a summer monsoon season each year, heavy rainfall is frequently occurred by passages of low pressure systems, mesoscale convective systems (MCSs), or typhoons over the Korean Peninsula. In particular, mountains that cover about 70% of the Korean territory play a significant role in formation, amount, and distribution of rainfall. Rapidly developing convective systems by orographic effects can greatly damage to property and human lives. To reduce the damages in mountainous regions, a better understanding of precipitation processes and structure of MCSs related to orographic effects is required.
In order to examine convective systems moving over mountainous regions, we performed intensive field observations at 9 sites around the Mt. Jiri (1950 m above sea level) during the summer 2016. Observation data from Parsivel disdrometers, ultrasonic anemometers (measuring winds) and rain gauges were collected during MCS events on July 2016. For the MCS events, a dual-Doppler radar analysis was also conducted to retrieve three-dimensional wind fields and vertical structure of reflectivity in this mountain area. Radiosonde data launched at the windward side were also analyzed to study thermodynamic conditions for occurrences of heavy rain. Drop size distribution (DSD) characteristics from Parsivel disdrometers and their relationship with vertical velocity observed by the anemometers were investigated at the Mt. Jiri.
Lastly, we performed model experiments to examine major contributing factors such as mean environmental flow, vertical air velocity, or horizontal convergence, affecting orographic precipitation enhancement. For simulations of orographic rainfall, we used Cloud-Resolving Storm Simulator (CReSS) with a resolution of 1-km grid size and the model results from sensitivity experiments by changing atmospheric factors as well as terrain height of Mt. Jiri are presented.
This work was funded by the Korea Meteorological Industry Promotion Agency under Grant KMIPA 2015-5060. This work was financially supported by the BK21 plus Project of the Graduate School of Earth Environmental Hazard System'