Conclusion : case study
Introduction to the Conclusion
In conclusion, to demonstrate that the precipitation discrepancy between Gunsan and Gangneung in South Korea in 2025 is not a phenomenon unique to Korea, we will analyze international cases with similar topographical conditions. Through this analysis, we aim to confirm the universal atmospheric dynamic principles by which the interaction of mountain ranges and wind direction influences squalls and localized torrential rainfall.
🏔️ Case 1. The Sierra Nevada Range
The Western United States is a region characterized by westerly winds carrying abundant moisture from the Pacific Ocean. When these humid westerly winds encounter the barriers of the Sierra Nevada Range and the Rocky Mountains, the orographic effect results in a large amount of precipitation on the western side due to the humid air, while the eastern side becomes dry.
Specifically, the Sierra Nevada Range, which is adjacent to the coast, primarily blocks the Pacific moisture, concentrating heavy snowfall and torrential rainfall in western California. The air, already dried out, then crosses the inland Rocky Mountains, accelerating the desiccation and air mass modification of the central North American continent.
As the air moves eastward, having already lost its moisture, it descends the leeward slope, undergoing a process called 'Adiabatic Warming' (or compressional heating). This causes the air to become even hotter and drier, simultaneously suppressing cloud formation. Consequently, this creates 'Rain Shadow' regions, such as the Death Valley (a desert), which experience an extremely low frequency of precipitation.
Similarity with the Korean Case
Sierra Nevada Mountains – Similar to the Gangneung Case: Partially analogous to the drought in Gangneung: The similarity lies in the suppression of precipitation and resulting drought on the eastern side of the Sierra Nevada Mountains, caused by the Foehn effect and other topographical influences.
Case 2. Eastern China: The South-Flood & North-Drought Pattern
This case, the South-Flood & North-Drought (SFND) Pattern is a precipitation disparity phenomenon where the southern Yangtze River basin experiences extreme heavy rainfall (flooding) while the northern North China Plain suffers from drought.
The root cause of this phenomenon lies in the expansion of the North Pacific High during the East Asian Monsoon period. When the stationary position of this high-pressure system is significantly shifted southward compared to normal years, or when the Westerly Jet Stream is displaced toward the south, it results in concentrated heavy rainfall in the south and dry conditions in the north.
Similarity with the Korean Case
The South (Yangtze River Basin) – Similar to the Gunsan Case:
In the southern region, a moist and intense Low-Level Jet (LLJ) develops more strongly than usual along the southward-shifted monsoon front. This LLJ transports a large volume of water vapor, causing strong, large-scale upward motion (convergence) at the frontal boundary. This is analogous to the phenomenon observed in Gunsan, where the intensified water vapor supply led to concentrated heavy rainfall.
< Conclusion >
In the summer of 2025, South Korea experienced a markedly extreme regional precipitation disparity compared to average years.
This precipitation disparity is a phenomenon caused by various and complex topographical and atmospheric circulation factors.
Case studies were helpful in hypothesizing the causes of this precipitation disparity phenomenon observed in Korea.
It was concluded that the follow-up project needs to further analyze the relationship between the frequency of heavy rainfall events and other meteorological factors besides temperature, and determine which element exerts the greatest influence on the occurrence of heavy rainfall.